WO2001004145A2 - Glutx polypeptide family and nucleic acids encoding same - Google Patents

Abstract

The present invention provides GLUTX1, GLUTX2 and GLUTX3, a family of novel isolated polypeptides, as well as a polynucleotides encoding GLUTX1, GLUTX2 and GLUTX3, and antibodies that immunospecifically bind to GLUTX1, GLUTX2 and GLUTX3, or any derivative, variant, mutant, or fragment of any one of the GLUTX family of polypeptides, polynucleotides or antibodies. The invention additionally provides methods in which the GLUTX family of polypeptides, polynucleotides and antibodies are used in detection and treatment of a broad range of pathological states, such as aberrant hexose transport, as well as to other uses.

Description

GLUTX POLYPEPTIDE FAMILY AND NUCLEIC ACIDS ENCODING SAME

FIELD OF THE INVENTION

The invention generally relates to novel nucleic acids and polypeptides and more particularly to novel nucleic acids encoding polypeptides related to glucose transporters

BACKGROUND OF THE INVENTION

Glucose transport across biological membranes requires the presence of specific integral membrane proteins that, m mammals, fall into two classes The first class includes the Na⁺/glucose cotransporters, SGLT1 and SGLT2, which are present mainly in the apical membrane of epithelial cells from intestine and kidney See, e g , Hediger and Rhoads 1994 Physiol Rev 74 993-1026 The second class includes the facihtative glucose carriers GLUT1, GLUT2, GLUT3, GLUT4 and GLUT5 (referred to collectively herein as "GLUT 1-5"), which are present in every tissue See, e g , Mueckler 1994 Eur J Biochem 219 713-725, Gould and Holman 1993 Biochem J 295 329-34 Much work has been devoted to the study of the GLUTs to determine their role in the control of glucose fluxes in different organs and their respective importance m the control of whole body glucose homeostasis Key roles for these transporters involve glucose absorption into the body, glucose uptake by the brain, storage in liver, insulin-dependent uptake in muscles and adipocytes, and glucose sensing by pancreatic cells See, e g , Thorens 1996 Am J Physiol 270 G541-G553, Rea and James 1997 Diabetes 46 1667-1677 Defects in any of these mechanisms may have profound pathophysiological consequences, in particular in the development of type 2 diabetes See, e g , Kahn 1998 Cell 92 593-596, Unger 1991 Science 251 1200-1205

Glucose (hexose) homeostasis requires the tight quantitative and temporal regulation of glucose flux into and out different organs The brain constantly needs a fixed supply of glucose for its own energy production and this requires that circulating glucose never decrease below a minimal level of ~5mM Glucose can enter the organism through the intestinal wall It is also produced endogenously by the liver what glucose is stored as glycogen or produced by the gluconeogenic pathway Absorption of glucose by muscle and adipose tissues m the postprandial state is a major component of glucose homeostasis and is required to prevent development of hyperglycemia These different glucose uptake and production mechanisms are under tight hormonal regulation In particular glucagon and insulin, produced by the alpha and beta cells of the Islets of Langerhans under hypoglycemic or hyperglycemic conditions, respectively, provide major control over these fluxes It is howe\ er now established that other glucose sensor umts present in different parts of the body participate in the fine control of glucose homeostasis It is known for instance that the hypothalamus contains glucose-sensing or glucose responsive neurons, the electrical activity of which is under positive or negative control by hypo or hyperglycemia These neurons participate in the control of food intake, activity of the autonomous nervous system and secretion of hormones from the endocrine pancreas or the adrenal gland A need remains to identify other components of the glucose homeostasis pathways in order to better treat diseases and disorders related to glucose (hexose) control, such as, e g , hyperglycemia and hypoglycemia

SUMMARY OF THE INVENTION

The invention is based in part on the discovery of a family of novel polypeptides, and nucleic acids encoding them, that are related to GLUT 1 -5 and GLUT8, and have hexose binding and or transport function GLUTX 1 , GLUTX2 and GLUTX3 comprise a related family of GLUTX polypeptides, as shown in at least human, rat and mouse Nucleic acid sequences and their encoded polypeptide sequences are provided for GLUTX 1 , GLUTX2 and GLUTX3 Consensus sequences for each GLUTX lsoform, as well as the GLUTX generic family, are also provided in the invension Conserved GLUTX polypeptide regions, and the nucleic acids encoding the same, are also provided Consensus sequences provide the means to clone other members of the GLUTX family of proteins, in addition to the GLUTX sequences provided herein Antibodies specific to GLUTX 1 , GLUTX2 and GLUTX3, and to a consensus GLUTX polypeptide, or fragments or derivatives thereof, are also described

Structural domains of GLUTX include transmembrane domains 1-12 (TM1 to TM12), interdomain loop legions, an ammo-terminal domain and a carboxy-terminal domain of the GLUTX polypeptides A GLUTX ammo-terminal domain and a carboxy-terminal domain aie defined as the tail regions prior to the first TM domain and after the last TM domain, respectively Regulatory sequences, including 5' UTR and 3' UTR, as well as methods of cloning promoter and enhancer regions of GLUTX genes, are described A dileucme motif, piesent in GLUTX 1, GLUTX2 and GLUTX3 polypeptides is required for regulating the localization of the expressed GLUTX protein GLUTX polypeptides mutated to no longei contain the N-ter dileucme repeat are provided for strong expression of the respective GLUTX protein on the cell surface, rather than having expressed GLUTX polypeptides being sequestered mtercellularly GLUTX polypeptides, nucleic acids and antibodies may be used to modify the regulation and expression of GLUTX polypeptides Methods of treatment of disorders associated with aberrant hexose transport, including but not limited to ischemia, diabetes, hyperglycemia and hypoglycemia, are described using GLUTX polypeptides, nucleic acids and antibodies Kits containing GLUTX polypeptides, nucleic acids and antibodies are also included GLUTX polypeptides and nucleic acids may be isolated, contained in expression vectors, in host cells, or in transgenic animals

GLUTX2 and GLUTX3 polypeptides are highly expressed in brain tissue, and are especially suited as targets in regulating ischemia and other hexose-related disorders in these tissues GLUTXl is highly expressed in testes, and is likewise a suitable candidate for treatments of hexose related disorders in these tissues

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety In the case of conflict, the present specification, including definitions, will control In addition, the materials, methods, and examples are illustrative only and not intended to be limiting Other features and advantages of the invention will be apparent from the following detailed description and claims

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 represents an alignment of GLUTXl with B vulgans integral membrane protein (IMP) (Swiss-Prot accession numbei Q39416, GenBank accession number AAB53155), E colt galactose proton symport (GALP) (Swiss-Prot accession number

P37021), L brevis xylose proton symport (XYLT) (Swiss-Prot accession number 052733), and rat GLUTs 1 -5 (Swiss-Prot accession numbers PI 1 166, PI 1 168, PI 1169, PI 4672, and P22732, respectively)

FIG 2 is a representation of the individual GLUTX proteins, wherein Panel A represents an alignment of GLUTXl mouse, rat, and human amino acid sequences, and Panel B represents an alignment of GLUTX2 human and rat ammo acid sequences

FIG 3 is a representation of the GLUTX family of polypeptides, wherein Panel A represents an alignment of human GLUTXl, GLUTX2 and GLUTX3 ammo acid sequences, and Panel B represents an alignment of rat GLUTXl , GLUTX2 and GLUTX3 amino acid sequences

FIG 4 is a graphic representation of the rat GLUTXl sequence, putative domains, and the ammo acid sequences used to construe fusion proteins with GST for antibody production FIG 5 is a graphic representation of GLUTX functionality, wherein Panel A presents

2-DOG uptake in Xenopus oocytes injected with GLUTXl wild-type (WT) RNA and GLUTXl (LL-AA) RNA compared with nomnjected control oocytes, Panel B presents the effect of competitors and inhibitors on uptake of 2-DOG in GLUTX l(LL-AA)-ιnjected oocytes, and Panel C presents a dose curve for uptake of 2-DOG in GLUTX l (LL-AA)- injected oocytes fitted using the Michaehs-Menten equation

FIG 6 is a graphic representation of the dose curve for uptake of myo-mositol in oocytes injected with 25 ng of GlutX2(RRR-AAA) RNA, fitted using the Michaehs-Menten equation

DETAILED DESCRIPTION OF THE INVENTION

Glucose (hexose) homeostasis requires the tight quantitative and temporal regulation of glucose flux into and out different organs Aberrant regulation of hexose transport in the body can lead to hyperglycemia, hypoglycemia, and the like Other disease models, e g , diabetes and ischemia, also involve aberrant regulation of or responses to hexose levels in the blood and surrounding tissues The brain constantly needs a fixed supply of glucose for its own energy production and this requires that circulating glucose never decrease below a minimal level of ~5mM It has indeed been shown that stimulation of activity of different brain regions is associated by increased glucose metabolism, that ischemia leads to increase glucose utilization and that diseases of the central nervous system may be associated with impaired stimulation of glucose uptake by specific brain areas Facihtative glucose transport, one of two mechanisms to regulate glucose in the body, is regulated by a family of proteins that include GLUT 1 -5 and GLUT8 See, e g , Carayannopoulos et al , 2000 PNAS 97 7313-7318 Structurally, the GLUTs form a family of highly related hexose transport proteins that belongs to a larger sugar transport superfamily consisting of more than 133 members distributed in a wide variety of species See, e g , Pao et αl 1998 Mic obwl Mol Biol Rev 62 1-34 These carrier proteins are characterized by the presence of 12 putative transmembrane ("TM") segments These may have evolved by duplication of an ancestral structure consisting of six transmembrane domains, as suggested by the presence of repeated structures in both halves of the molecule These aie GR(R/K) ammo acid motifs present between TM2 and TM3 and between TM8 and TM9 and the EX₆(R/K) amino acid motifs present between TM4 and TM5 and between TM10 and TM11

Within the mammalian glucose transporters, additional motifs have been characterized that are essential for transporter function For instance, site-directed mutagenesis studies have suggested that a QLS motif present in TM7 of the high affinity glucose transporters GLUTl, 3, and 4 is important in defining binding affinity and selection of the incoming hexose See, e g , Seatter et α/ 1998 Biochemistry 37 1322-1326 Immediately following this motif is a conserved pair of glutamine residues The first one, Glu of GLUTl , is required for binding of the glucose competitive inhibitor ATB-BMPA on the exofacial glucose binding site See, e g , Hashiramoto et al 1992 J Biol Chem 267 17502-17507 Importantly also, the intracellularly located tryptophan residues 388 and 412 of GLUTl , which are conserved in GLUT2-4, paiticipate in the conformational changes required for transport activity and for binding the competitive inhibitor cytochalasin B See, e g , Inukai et al 1994 Biochem J 302 355-361 , Garcia et al 1992 J Biol Chem 267 7770-7776, Saravolac and Holman, 1997 In FACILITATE E GLUCOSE TRANSPORTERS, pp 39-66, R G Landes and Co , Georgetown, TX The invention is based in part on the discovery of novel GLUTX nucleic acid sequences encoding polypeptides similar to the facihtative glucose transporters GLUTl -5 (Swiss-Prot accession numbers PI 1 166, PI 1 168, PI 1 169, PI 4672, and P22732) The novel nucleic acids descπbed herein and their encoded polypeptides are referred to collectively as "GLUTX"

The invention describes the cloning and functional characterization of novel glucose transporter proteins, including at least GLUTXl , GLUTX2 and GLUTX3, identified by data base homology searches using sequences of the known GLUTs The GLUTX proteins share the same overall structure as the GLUTs and contains key glucose transporter sequence motifs However, the GLUTXs have some distinctive structural features In addition, GLUTXs have a higher homology to plant and bacterial sequences than to the mammalian GLUTs, and thus describe a novel family of mammalian facilitated glucose transporters

GLUTXl

Included in the invention is GLUTXl , a novel glucose transporter-related polypeptide, and nucleic acids encoding the GLUTXl polypeptide Antibodies that bind specifically to

GLUTXl polypeptides, or fragments thereof, are also included in the invention The invention further includes fragments, homologs, analogs, and derivatives of GLUTXl nucleic acids, polypeptides, and antibodies Homologs and analogs of GLUTXl nucleic acids and proteins include at least human, rat and mouse vaπants described below and in GenBank™/EMBL Data Bank accession numbers: NM_014580, NP_055395, AJ245937 and CAB75702 (human),

AJ245935 and CAB75729 (rat), and AJ245936 and CAB75719 (mouse). See, Ibberson et al., 2000 J. Biol. Chem. 275: 4607-4612.

Similarly to GLUTsl-5, GLUTXl contains 12 putative membrane spanning domains, shown in FIG. 1 , with a large cytoplasmic loop between TM 6 and TM7 but a short first exoplasmic loop which does not contain a N-glycosylation site. However, an N-glycosylation site is present in an exoplasmic loop between TM9 and TM10. This loop shows no significant homology with the other mammalian glucose transporter proteins. GLUTXl protein sequence shows the highest degree of homology with nonmammalian sugar transporters. Identity is 36%o with a putative sugar transporter from sugar beet, termed integral membrane protein (GenBank accession number AAB53155). See, e.g., Chiou and Bush 1996 Plant Physiol. 1 10: 51 1 -520. In addition, identity is 35% with Escherichia coli galactose-proton symport (GALP), 32% with Lactobacillas brevis xylose proton symport (XYLT), and between 29 and 32% with the other mammalian glucose transporters. Importantly, sequences that have been reported to be critical for the glucose transport function are present in GLUTXl at conserved locations. These include the two repeated sequence motifs GR(R/K) and EX₆(R/K) and two tryptophan residues, Trp^3< and Trp⁴¹⁹, corresponding to Tip³⁸⁸ and Tip⁴¹² of GLUTl . Interestingly, a dileucine motif is found in the amino-terminal cytoplasmic domain of the protein. Human, rat and mouse GLUTXl sequences have been determined and are shown in Tables 3 A, 3B and 3C, respectively.

Immunofluorescence and microscopic analyses were used to detect GLUTXl and mutant GLUTX l(LL-AA) in HEK293T cells using the GLUTXl (203-257) antibody (see EXAMPLES). Secondary antibody was conjugated to CY3. The data indicate that the intracellular location of GLUTXl depends on the presence of the dileucine internalization motif. Using extrapolation of the similarities between GLUTX family members, as defined in the EXAMPLES, one skilled in the arts would understand that the dileucine repeat may have similar or identical function in GLUTX2 and GLUTX3. Alternative embodiments of the invention include alternative sequences of any one of the GLUTX polypeptides of the invention, including GLUTXl, GLUTX2 or GLUTX3, wherein the dileucine repeat is changed to alternative amino acids, either as a repeat of a single type of amino acid, e.g., dialanine, or as two separate but adjacent amino acids, e.g., alanine serine, valine methionine, and the like. Substituted amino acids may be chosen from either the "strong" or "weak" groups of conserved amino acid residues, as defined below and in Example 1, or may be nonconserved. The dileucine motif is present at amino acids 12-13 of SEQ ID NO:2, amino acids 12-13 of SEQ ID NO:4, ammo acids 12-13 of SEQ ID NO:6, amino acids 22-23 of SEQ

ID NO:8, amino acids 20-21 of SEQ ID NO: 10, amino acids 5-6 of SEQ ID NO: 12, and amino acids 5-6 of SEQ ID NO:14.

A DNA sequence of a human GLUTXl gene (2217 nucleotides; SEQ ID NO: l), and its encoded amino acid sequence (SEQ ID NO:2), are shown in Table 3A. The translated protein is encoded from nucleotide 348 to 1778. The human GLUTXl protein product (SEQ ID NO:2) is 477 amino acids in length. The predicted molecular weight of the human GLUTXl polypeptide is 50858.1 Da.

A DNA sequence of a rat GLUTXl gene (2087 nucleotides; SEQ ID NO:3), and its encoded amino acid sequence (SEQ ID NO:4), are shown in Table 3B. The translated protein is encoded from nucleotide 30 to 1463. The rat GLUTXl protein product (SEQ ID NO:4) is 478 amino acids in length. The predicted molecular weight of the rat GLUTXl polypeptide is 51459.0 Da.

A DNA sequence of a mouse GLUTXl gene (2072 nucleotides; SEQ ID NO:5), and its encoded amino acid sequence (SEQ ID NO:6), are shown in Table 3C. The translated protein is encoded from nucleotide 21 to 1451. The mouse GLUTXl protein product (SEQ ID NO:6) is 477 amino acids in length. The predicted molecular weight of the mouse GLUTXl polypeptide is 51578.0 Da.

Further analyses of the GLUTXl sequences are shown in the EXAMPLES section. Mouse and rat GLUTXl are most similar, showing 91 > identity at the nucleotide and

94% identity at the amino acid sequence level; human GLUTXl is more divergent, showing 85% identity with both the nucleotide and the protein sequence of rat and mouse GLUTXl (FIG. 2).

Sequence comparison indicated that rat GLUTXl was 29-32% identical to the GLUTs, whereas the GLUTs are between 40 and 70% identical to each other. Highest sequence identity (36%) was with a putative sugar transporter (integral membrane protein) cloned from sugar beet and with bacterial galactose/and xylose/proton cotransporters (35%). See, e.g., Chiou and Bush 1996 Plant Physiol. 1 10: 51 1-520. Four small regions of GLUTXl (45-49, 70-74, 181 - 188, and 398-403) show almost perfect conservation with integral membrane protein sequences that are only very distantly related to sequences at the same locations in GLUTs

(indicated in FIG. 1 ). These regions imply differences in evolutionary origin and/or differences in structural requirements for GLUTXl compared with the GLUTs.

Interestingly, one unique feature of GLUTXl is the long exoplasmic loop present between TM9 and TM10 that contains the only TV-glycosylation site of the molecule. This sequence has no counterpart in the GLUTs or in the related plant or bacterial transporters mentioned above However, a counterpart to this sequence does exist in GLUTX2 and GLUTX3, and GLUTX2 and GLUTX3 are presumed to contain similar domain structures as GLUTXl , as shown in FIG 3 and the EXAMPLES By using Smith-Waterman sequence similarity search using rat GLUTXl, we found that this sequence contains a stretch (ammo acids 341 -362) that is similar (54% identical over 22 residues) to a segment (ammo acids 333- 354) of the msmF multiple sugar receptor/transporter of 5 mutans See, e g , Smith et al 1985 Nucleic Acids Res 13 645-656 The msmF protein has six putative transmembrane domains and forms part of a system responsible for the uptake and metabolism of multiple sugars and is closely l elated to the maltose transport system of E coli See, e g , Russell et al 1992 J Biol Chem 267 4631-4637 This similarity is at present of unknown functional importance but may point to a structure that participates in sugar binding

Chimeric and mutant glucose transporters have been widely used for the study of the structure/function of the GLUTs See, e g , review in Saravolac and Holman 1997 In FACILITATIVE GLUCOSE TRANSPORTERS , pp 39-66, R G Landes and Co , Georgetown, TX A recent study has identified the QLS sequence in transmembrane domain 7 of GLUTl , 3,4 as a motif critical for hexose selection at the exofacial binding site Replacing this sequence with that of human GLUT2 led to fructose, in addition to glucose, transport activity of the mutated transporter GLUTXl has MVF at this position instead of QLS See, e g , Seatter et al 1998 Biochemistry 31 1322-1326 This suggests that it may transport other hexoses beside glucose Our oocyte uptake experiments indeed show that both fructose and galactose can compete for 2-DOG transport

One distinguishing feature of GLUTXl as compared with the GLUTs is its relatively short carboxyl-terminal cytoplasmic tail, which has a predicted length of 20 ammo acids as compared to 42-45 amino acids for GLUTs 1-5 Deletion studies of GLUTl have suggested that its carboxyl-terminal tail was important for allowing conformational changes that accompany glucose transport Removing 37 ammo acids of the GLUTl tail suppressed glucose transport by locking the transporter in an inward facing conformation See, e g , Oka et al 1990 Natui e 345 550-553 However, shorter truncations, up to 24 amino acids (leaving an 18- amino acid-long carboxyl-terminal tail), did not affect on transport activity or cytochalasm B binding See, e g , Saravolac and Holman 1997 In FACILITATIVE GLUCOSE TRANSPORTERS , pp 39-66, R G Landes and Co , Georgetown, TX Therefore, by analogy, the short cytoplasmic tail of GLUTXl should still permit normal transport activity This was indeed confirmed by oocyte expression studies, see the EXAMPLES These functional expeπments were, however, successful only after mutation of the dileucme motif present in the ammo- terminal tail of the molecule Transport was not inhibited by an excess of L-glucose, suggesting stereospecificity of the transport mechanism Transport was cytochalasin B- sensitive, which is compatible with the presence of tryptophan at positions 395 and 419, which correspond to Tip³⁸ and Trp^{41 "} of GLUTl Transport was also indicated for fructose and galactose as assessed by competition experiments The K,„ for 2-DOG, as determined m zero- trans experiments, was ~2 4 mM This value is similar to that of GLUT3, which is the highest affinity transporter of the GLUT family See, e g , Gould and Holman 1993 Biochem J 295 329-341 A possible physiological role for GLUTXl can be suggested based on both its tissue and cellular localization First, its mtracellular location suggests that it is not involved in basal cellular glucose uptake However, similarly to GLUT4, GLUTXl contains a dileucine lnternahzation motif In GLUT4, this motif, located in the carboxyl-terminal cytoplasmic tail, functions as signal for re-endocytosis following surface expression, which occurs either as part of a basal recycling process or following stimulation by insulin See, e g , Verhey and

Birnbaum 1994 J Biol Chem 269 2353-2356, Corvera et al 1994 J Cell Biol 126 979-989 In GLUTXl, the dileucme motif appears essential for maintaining the mtracellular localization of the transporter as assessed both in transfected HEK293T cells and m neuroendocπne cells² and as inferred from Xenopus oocytes functional studies This therefore suggests that in its normal life cycle, GLUTXl recycles between an mtracellular site and the plasma membrane Therefore, one possible role for this transporter may be to increase cellular glucose uptake in i espouse to certain stimuli Those could be hormones such as insulin or neurotransmitters but also other factors such as stresses induced by, for instance, hypoxia or hypoglycemia

The high level of GLUTXl expression in testis suggests that this glucose transporter could function to promote glucose and fructose transport in the developing spermatocyte alongside GLUT3 and GLUT5, which are also known to be expressed in testis See, e g , Burant et al 1992 J Biol Chem 267 14523-14526, Younes et al 1997 Anticancer Res 17 2747-2750 GLUTXl expression is relatively high in the bram stem and hypothalamus where glucose-sensing neurons are located and that respond to hyperglycemia or hypoglycemia by increasing or decreasing their firing rates See, e g , Oomura et al 1974 Natw e lAl 284-286, Yettefti et α/ 1995 J Auton Nerv Svst 51 191-197, Orsini et al 1990 Brain Res Bull 25 49-53 It is therefore possible that GLUTXl plays a role in some of these glucose-sensing mechanisms or in some adaptive functions Finally, recent studies performed with knockout mice have revealed the existence of glucose transport activity that could not be accounted for by any of the known GLUTs This was the case in the pancreatic cells of GLUT2-null mice, which are characterized by a loss of first phase insulin secretion but which have a preserved second phase This remaining glucose secretory activity still depends on glucose uptake and metabolism See, e g , Guillam et al 1991 Nat Genet 17 327-330 Glucose uptake, however, cannot be accounted for by any other known GLUTs This was also the case in some muscles of GLUT4-null mice in which glucose uptake can still be stimulated by an insulin- dependent mechanism that does not appear to involve GLUTl -5 See, e g , Stenbit et al 1997 J Chn Invest 98 629-634 Further localization studies, at the tissue and cellular levels, as well as evaluation of a mechanism that may induce GLUTXl surface expression will ultimately be required to more fully elucidate the physiological role of this transporter

GLUTX2

Included in the invention is GLUTX2, a novel glucose transporter-related polypeptide, and nucleic acids encoding the GLUTX2 polypeptide Antibodies that bind specifically to GLUTX2 polypeptides, or fragments thereof, are included in the invention The invention further includes fragments, homologs, analogs, and derivatives of GLUTX2 nucleic acids, polypeptides, and antibodies Human and rat GLUTX2 sequences have been determined, and are shown in Tables 4A and 4B, respectively Further analyses of the GLUTX2 sequences are shown in the EXAMPLES section

A DNA sequence of a human GLUTX2 gene (2177 nucleotides, SEQ ID NO 7), and its encoded amino acid sequence (SEQ ID NO 8), are shown in Table 4A The translated protein is encoded from nucleotide 288 to 2174 The human GLUTX2 protein product (SEQ ID NO 8) is 629 amino acids in length The predicted molecular weight of the human GLUTX2 polypeptide is 68336 2 daltons (Da)

A DNA sequence of a rat GLUTX2 gene (2504 nucleotides, SEQ ID NO 9), and its encoded ammo acid sequence (SEQ ID NO 10), are shown in Table 4B The translated protein is encoded from nucleotide 145 to 1998 The rat GLUTX2 protein product (SEQ ID NO 10) is 618 amino acids in length The predicted molecular weight of the rat GLUTX2 polypeptide is 66995 0 daltons

GLUTX2 proteins are predominantly expressed in the brain Further analyses of GLUTX2 localization, structuie and homologies are shown in the EXAMPLES

GLUTX3

Included in the invention is GLUTX3, a novel glucose transporter-related polypeptide, and nucleic acids encoding the GLUTX3 polypeptide Antibodies that bind specifically to GLUTX3 polypeptides, or fragments thereof, are included in the invention The invention further includes fragments, homologs, analogs, and derivatives of GLUTX3 nucleic acids, polypeptides, and antibodies Human and rat GLUTX3 sequences have been determined and are shown in Tables 5A and 5B, respectively A DNA sequence of a human GLUTX3 gene (1541 nucleotides, SEQ ID NO 11), and its encoded ammo acid sequence (SEQ ID NO 12), are shown in Table 5 A The translated protein is encoded from nucleotide 11 to 1531 The human GLUTX3 protein product (SEQ ID NO 12) is 507 amino acids in length The predicted molecular weight of the human GLUTX3 polypeptide is 54456 7 daltons A DNA sequence of a rat GLUTX3 gene (201 1 nucleotides, SEQ ID NO 13), and its encoded amino acid sequence (SEQ ID NO 14), are shown in Table 5B The translated protein is encoded from nucleotide 7 to 1515 The rat GLUTX3 protein product (SEQ ID NO 14) is 503 amino acids in length The predicted molecular weight of the rat GLUTX3 polypeptide is 54899 9 daltons GLUTX3 proteins are predominantly expressed in the brain Further analyses of

GLUTX3 localization, structure and homologies are shown in the EXAMPLES

GLUTX Consensus Sequence

Included in the invention are the polypeptide sequences of members of the GLUTX family of proteins, and the nucleic acids encoding those GLUTX polypeptides Antibodies that bind specifically to GLUTX polypeptides, or fragments thereof, are included m the invention Antibodies may be made to the various domains of the GLUTX polypeptides Embodiments of the invention include the various TM domains, denoted as TM1 through TM 12 in Tables 3D, 4C and 5C and in FIG 1 Additional GLUTX domains of the invention include the N-ter, C- ter, and loop regions between the various TM regions descπbed therein Further embodiments of invention include domains with high conservation between members of the GLUTX protein family, including those domains underlined in Tables 6A, 6B and 6D, and those stretches of residues shown in FIG 3 with black or gray shading Domains with high conservation between GLUTX polypeptides and the related GLUT family members are shown as black or gray shaded residues in FIG 1 The nucleic acid, polypeptide, or both, sequences of the exoplasmic loop between TM9 and TM10 may be another targeted GLUTX domain

Antibodies may be made to any one or more of these GLUTX protein domains Antibodies specific to an individual GLUTX polypeptide may be made to non-consensus sequences Antibodies with broader recognition, i e , to more than one member of the GLUTX polypeptide family, may be made against a consensus GLUTX specific sequence Antibodies made to consensus shaded residues shown in FIG. 1 may have even broader recognition to both the GLUTX and GLUT polypeptides. Antibodies may be made as described below.

Embodiments of the invention include GLUTX consensus nucleic acids and polypeptides encoded thereby, as well as fragments, homologs and analogs of said GLUTX consensus nucleotids and polypeptides. Antibodies to these consensus sequences, and fragments, homologs and analogs thereof, are also included in the invention, as described above. A human GLUTX polypeptide consensus sequence (SEQ ID NO: 18) is shown in Table 6A. The human GLUTX consensus polypeptide sequence was derived from the Majority sequence (SEQ ID NO:21 ) from the human GLUTX alignment shown in Table 6E, and is further discussed in the EXAMPLES section. A ClustalX alignment of the rat GLUTX polypeptides is shown in FIG. 2. A rat GLUTX consensus sequence (SEQ ID NO: 19) derived from the FIG. 3 alignment is shown in the Examples in Table 6B. An alternative alignment to FIG. 3, centered around the putative glycosylated N residue of GLUTXl -3, is shown in Table 6C, and the alternative rat GLUTX consensus sequence (SEQ ID NO:20) derived from the alternative alignment of Table 6C is shown in Table 6D. Finally, ClustalW alignment and a Majority sequence for rat GLUTX (SEQ ID NO:21) are shown in Table 6E. Predicted consensus sequences that appear specific to the GLUTX family of polypeptides are indicated by underlines.

Alternative embodiments of the invention include nucleic acids that encode these GLUTX consensus polypeptide sequence, which may be derived by a person skilled in the arts from the genetic code specifying codon designations for the various amino acid residues. Further analyses of the GLUTX consensus sequences are shown in the EXAMPLES section.

The invention also includes regulartory sequences of GLUTX nucleic acids. Regulatory sequences include the 5' untranslated region (UTR), 3' UTR, and promoter and enhances elements, described below, of any GLUTX gene disclosed herein. The specific 5' UTRs and 3' UTRs of any of the individual GLUTX sequences may be labeled by any method known to one skilled in the art, e.g., radiolabeling or fluorescence labeling as discussed below, and used to probe nucleic acid sequences, e.g., genomic sequences, to identify and isolate flanking regulatory regions for the specific GLUTX gene being probed. Table 1 below summarizes the disclosed the 5' UTR, coding region (CDS), length in amino acids of the predicted GLUTX polypeptide, and 3 ' UTR for the various GLUTX genes disclosed herein. TABLE 1

GLUTX Nucleic Acids

TABLE 2 below summarizes the disclosed GLUTX nucleic acid sequences, encoded polypeptides, and the corresponding sequence identifier numbers (SEQ ID NOs) for the various disclosed sequences and clones containing these nucleic acids and polypeptides.

TABLE 2: Summary Of Nucleic Acids And Proteins Of The Invention

The novel nucleic acids of the invention include those that encode a GLUTX or GLUTX-like protein. Among these nucleic acids is the nucleic acid whose sequence is provided in SEQ ID NO: l, 3, 5, 7, 9, 1 1 or 13, or a fragment, derivative or homolog thereof. Additionally, the invention includes mutant or variant nucleic acids of SEQ ID NO:l, 3, 5, 7, 9, 1 1 or 13, or a fragment, derivative or homolog thereof, any of whose bases may be changed from the corresponding base shown in SEQ ID NO:l, 3, 5, 7, 9, 1 1 or 13, while still encoding a protein that maintains its GLUTX -like activities and physiological functions. The invention further includes the complement of the nucleic acid sequence of SEQ ID NO:l, 3, 5, 7, 9, 11 or 13, including fragments, derivatives, analogs and homolog thereof. Examples of the complementary strand of portions of GLUTX may be determined by Watson-Cπck base pairing, wherein adenme (A) pairs with thymidine (T) and guanine (G) pairs with cytosme (C), which is known to anyone skill in the art The invention additionally includes nucleic acids or nucleic acid fragments, or complements thereto, whose structures include chemical modifications

One aspect of the invention pertains to isolated nucleic acid molecules that encode GLUTX proteins or biologically active portions thereof Also included are nucleic acid fragments sufficient for use as hybridization probes to identify GLUTX-encodmg nucleic acids (e g , GLUTX mRNA) and fragments for use as polymerase chain reaction (PCR) primers for the amplification or mutation of GLUTX nucleic acid molecules As used herein, the teπn "nucleic acid molecule" is intended to include DNA molecules (e g , cDNA or genomic DNA), RNA molecules (e g , mRNA), analogs of the DNA or RNA generated using nucleotide analogs, and derivatives, fragments and homologs thereof The nucleic acid molecule can be single-stranded or double-stranded, but preferably is double-stranded DNA "Probes" refer to nucleic acid sequences of variable length, preferably between at least about 10 nucleotides (nt), 100 nt, or as many as about, e g , 6,000 nt, depending on use Probes are used in the detection of identical, similar, or complementary nucleic acid sequences Longer length probes are usually obtained from a natural or recombinant source, are highly specific and much slower to hybridize than ohgomers Probes may be single- or double-stranded and designed to have specificity in PCR, membrane-based hybridization technologies, or ELISA-hke technologies

An "isolated" nucleic acid molecule is one that is separated from other nucleic acid molecules that are present in the natural source of the nucleic acid Examples of isolated nucleic acid molecules include, but are not limited to, recombinant DNA molecules contained in a vector, recombinant DNA molecules maintained in a heterologous host cell, partially or substantially purified nucleic acid molecules, and synthetic DNA or RNA molecules Preferably, an "isolated" nucleic acid is free of sequences which naturally flank the nucleic acid (i e , sequences located at the 5' and 3' ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived For example, in various embodiments, the isolated GLUTX nucleic acid molecule can contain less than about 50 kb, 25 kb, 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0 5 kb or 0 1 kb of nucleotide sequences which naturally flank the nucleic acid molecule in genomic DNA of the cell from which the nucleic acid is derived Moreover, an "isolated" nucleic acid molecule, such as a cDNA molecule, can be substantially free of other cellular material or culture medium when produced by recombinant techniques, or of chemical precursors or other chemicals when chemically synthesized.

A nucleic acid molecule of the present invention, e.g., a nucleic acid molecule having the nucleotide sequence of SEQ ID NO:l, 3, 5, 7, 9, 11 or 13 or a complement of any of this nucleotide sequence, can be isolated using standard molecular biology techniques and the sequence information provided herein. Using all or a portion of the nucleic acid sequence of SEQ ID NO:l, 3, 5, 7, 9, 1 1 or 13 as a hybridization probe, GLUTX nucleic acid sequences can be isolated using standard hybridization and cloning techniques (e.g., as described in Sambrook et al., eds., MOLECULAR CLONING: A LABORATORY MANUAL 2^nd Ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989; and Ausubel, et al, eds., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, New York, NY, 1993.)

A nucleic acid of the invention can be amplified using cDNA, mRNA or alternatively, genomic DNA, as a template and appropriate oligonucleotide primers according to standard PCR amplification techniques. The nucleic acid so amplified can be cloned into an appropriate vector and characterized by DNA sequence analysis. Furthermore, oligonucleotides corresponding to GLUTX nucleotide sequences can be prepared by standard synthetic techniques, e.g. , using an automated DNA synthesizer.

As used herein, the term "oligonucleotide" refers to a series of linked nucleotide residues, which oligonucleotide has a sufficient number of nucleotide bases to be used in a PCR reaction. A short oligonucleotide sequence may be based on, or designed from, a genomic or cDN A sequence and is used to amplify, confirm, or reveal the presence of an identical, similar or complementary DNA or RNA in a particular cell or tissue. Oligonucleotides comprise portions of a nucleic acid sequence having about 10 nt, 50 nt, or 100 nt in length, preferably about 15 nt to 30 nt in length. In one embodiment, an oligonucleotide comprising a nucleic acid molecule less than 100 nt in length would further comprise at lease 6 contiguous nucleotides of SEQ ID NO: l, 3, 5, 7, 9, 1 1 or 13 or a complement thereof. Oligonucleotides may be chemically synthesized and may be used as probes.

In another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule that is a complement of the nucleotide sequence shown in SEQ ID

NO:l, 3, 5, 7, 9, 1 1 or 13. In another embodiment, an isolated nucleic acid molecule of the invention comprises a nucleic acid molecule that is a complement of the nucleotide sequence shown in SEQ ID NO:l, 3, 5, 7, 9, 11 or 13 or a portion of this nucleotide sequence. A nucleic acid molecule that is complementary to the nucleotide sequence shown in SEQ ID NO:l, 3, 5, 7, 9, 1 1 or 13 is one that is sufficiently complementary to the nucleotide sequence shown in

SEQ ID NO 1, 3, 5, 7, 9, 11 or 13 that it can hydrogen bond with little or no mismatches to the nucleotide sequence shown in SEQ ID NO 1 , 3, 5, 7, 9, 1 1 or 13 , thereby forming a stable duplex As used herein, the term "complementary" refers to Watson-Crick or Hoogsteen base pairing between nucleotides units of a nucleic acid molecule, and the term "binding" means the physical or chemical interaction between two polypeptides or compounds or associated polypeptides or compounds or combinations thereof Binding includes ionic, non-ionic, Von der Waals, hydrophobic interactions, etc A physical interaction can be either direct or indirect Indirect interactions may be through or due to the effects of another polypeptide or compound Direct binding refers to interactions that do not take place through, or due to, the effect of another polypeptide or compound, but instead are without other substantial chemical intermediates

Moreover, the nucleic acid molecule of the invention can comprise only a portion of the nucleic acid sequence of SEQ ID NO 1 , 3, 5, 7, 9, 1 1 or 13 , e g , a fragment that can be used as a probe or primer, or a fragment encoding a biologically active portion of GLUTX "Fragments" provided herein are defined as sequences of at least 6 (contiguous) nucleic acids or at least 4 (contiguous) ammo acids, a length sufficient to allow for specific hybπdization in the case of nucleic acids or for specific recognition of an epitope in the case of amino acids, respectively, and are at most some portion less than a full length sequence Fragments may be derived from any contiguous portion of a nucleic acid or amino acid sequence of choice "Derivatives" are nucleic acid sequences or amino acid sequences formed from the native compounds either directly or by modification or partial substitution "Analogs" are nucleic acid sequences or amino acid sequences that have a structure similar to, but not identical to, the native compound but differs from it in respect to certain components or side chains

Analogs may be synthetic or from a different evolutionary origin and may have a similar or opposite metabolic activity compared to wild type

Derivatives and analogs may be full length or other than full length, if the derivative or analog contains a modified nucleic acid or amino acid, as described below Derivatives or analogs of the nucleic acids or proteins of the invention include, but are not limited to, molecules comprising regions that are substantially homologous to the nucleic acids or proteins of the invention, in various embodiments, by at least about 70%, 80%, 85%, 90%, 95%o, 98%, or even 99% identity (with a preferred identity of 80-99%>) over a nucleic acid or amino acid sequence of identical size or when compared to an aligned sequence in which the alignment is done by a computer homology program known in the art, or whose encoding nucleic acid is capable of hybridizing to the complement of a sequence encoding the aforementioned proteins under stringent, moderately stringent, or low stringent conditions. See e.g. Ausubel, et al, CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, New York, NY, 1993, and below. An exemplary program is the Gap program (Wisconsin Sequence Analysis Package, Version 8 for UNIX, Genetics Computer Group, University Research Park, Madison, WI) using the default settings, which uses the algorithm of Smith and Waterman (Adv. Appl. Math., 1981, 2: 482-489, which is incorporated herein by reference in its entirety). A "homologous nucleic acid sequence" or "homologous amino acid sequence," or variations thereof, refer to sequences characterized by a homology at the nucleotide level or amino acid level as discussed above. Homologous nucleotide sequences encode those sequences coding for isofomis of GLUTX polypeptide. Isoforms can be expressed in different tissues of the same organism as a result of. for example, alternative splicing of RNA. Alternatively, isofomis can be encoded by different genes. In the present invention, homologous nucleotide sequences include nucleotide sequences encoding for a GLUTX polypeptide of species other than humans, including, but not limited to, mammals, and thus can include, e.g., mouse, rat, rabbit, dog, cat cow, horse, and other organisms. Homologous nucleotide sequences also include, but are not limited to, naturally occurring allelic variations and mutations of the nucleotide sequences set forth herein. A homologous nucleotide sequence does not, however, include the nucleotide sequence encoding human GLUTX protein. Homologous nucleic acid sequences include those nucleic acid sequences that encode conservative amino acid substitutions (see below) in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , as well as a polypeptide having GLUTX activity. Biological activities of the GLUTX proteins are described below. A homologous amino acid sequence does not encode the amino acid sequence of a human GLUTX polypeptide.

The nucleotide sequence determined from the cloning of the human GLUTX gene allows for the generation of probes and primers designed for use in identifying and/or cloning GLUTX homologues in other cell types, e.g., from other tissues, as well as GLUTX homologues from other mammals. The probe/primer typically comprises a substantially purified oligonucleotide. The oligonucleotide typically comprises a region of nucleotide sequence that hybridizes under stringent conditions to at least about 12, 25, 50, 100, 150, 200, 250, 300, 350 or 400 or more consecutive sense strand nucleotide sequence of SEQ ID NO:l, 3, 5, 7, 9, 11 or 13, or an anti-sense strand nucleotide sequence of SEQ ID NO 1, 3, 5, 7, 9, 11 or 13, or of a naturally occurring mutant of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13

Probes based on the human GLUTX nucleotide sequence can be used to detect transcripts or genomic sequences encoding the same or homologous proteins In various embodiments, the probe further comprises a label group attached thereto, e g , the label group can be a radioisotope, a fluorescent compound, an enzyme, or an enzyme co-factor Such probes can be used as a part of a diagnostic test kit for identifying cells or tissue which misexpress a GLUTX protein, such as by measuring a level of a GLUTX-encoding nucleic acid in a sample of cells from a subject e g , detecting GLUTX mRNA levels or determining whether a genomic GLUTX gene has been mutated or deleted

A "polypeptide having a biologically active portion of GLUTX" refers to polypeptides exhibiting activity similar, but not necessarily identical to, an activity of a polypeptide of the present invention, including mature forms, as measured in a particular biological assay, with or without dose dependency A nucleic acid fragment encoding a "biologically active portion of GLUTX" can be prepared by isolating a portion of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 that encodes a polypeptide having a GLUTX biological activity (biological activities of the GLUTX proteins are described below), expressing the encoded portion of GLUTX protein (e g , by recombinant expression in vitro) and assessing the activity of the encoded portion of GLUTX For example, a nucleic acid fragment encoding a biologically active portion of GLUTX can optionally include an ATP-binding domain In another embodiment, a nucleic acid fragment encoding a biologically active portion of GLUTX includes one or more regions

GLUTX variants

The invention further encompasses nucleic acid molecules that differ from the nucleotide sequences shown in SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 due to degeneracy of the genetic code These nucleic acids thus encode the same GLUTX protein as that encoded by the nucleotide sequence shown in SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 In another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence shown in SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 In addition to the human GLUTX nucleotide sequence shown in SEQ ID NO 1, 3, 5, 7,

9, 1 1 or 13, it will be appreciated by those skilled in the art that DNA sequence polymorphisms that lead to changes m the amino acid sequences of GLUTX may exist within a population (e g , the human population) Such genetic polymorphism in the GLUTX gene may exist among individuals within a population due to natural allelic vaπation As used herein, the terms "gene" and "recombinant gene" refer to nucleic acid molecules comprising an open reading frame encoding a GLUTX protein, preferably a mammalian GLUTX protein Such natural allelic variations can typically result in 1-5% variance in the nucleotide sequence of the GLUTX gene Any and all such nucleotide variations and resulting ammo acid polymorphisms in GLUTX that are the result of natural allelic variation and that do not alter the functional activity of GLUTX are intended to be within the scope of the invention

Moreover, nucleic acid molecules encoding GLUTX proteins from other species, and thus that have a nucleotide sequence that differs from the human sequence of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 are intended to be within the scope of the invention Nucleic acid molecules corresponding to natural allelic variants and homologues of the GLUTX cDNAs of the invention can be isolated based on their homology to the human GLUTX nucleic acids disclosed herein using the human cDNAs, or a portion thereof, as a hybridization probe according to standard hybridization techniques under stringent hybridization conditions For example, a soluble human GLUTX cDNA can be isolated based on its homology to human membrane-bound GLUTX Likewise, a membrane-bound human GLUTX cDNA can be isolated based on its homology to soluble human GLUTX

Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention is at least 6 nucleotides in length and hybridizes under stringent conditions to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 In another embodiment, the nucleic acid is at least 10, 25, 50, 100, 250, 500 or 750 nucleotides in length In another embodiment, an isolated nucleic acid molecule of the invention hybridizes to the coding region As used herein, the term "hybridizes under stringent conditions" is intended to describe conditions for hybridization and washing under which nucleotide sequences at least 60% homologous to each other typically remain hybridized to each other

Homologs (i e nucleic acids encoding GLUTX proteins derived from species other than human) or other related sequences (e g , paralogs) can be obtained by low, moderate or high stringency hybridization with all or a portion of the particular human sequence as a probe using methods well known in the art for nucleic acid hybridization and cloning As used herein, the phrase "stringent hybridization conditions" refers to conditions under which a probe, primer or oligonucleotide will hybridize to its target sequence, but to no other sequences Stringent conditions are sequence-dependent and will be different in different circumstances Longer sequences hybridize specifically at higher temperatures than shorter sequences Generally, stringent conditions are selected to be about 5°C lower than the thermal melting point (T_m) for the specific sequence at a defined ionic strength and pH. The

Tm is the temperature (under defined ionic strength, pH and nucleic acid concentration) at which 50% of the probes complementary to the target sequence hybridize to the target sequence at equilibrium. Since the target sequences are generally present at excess, at Tm, 50% of the probes are occupied at equilibrium. Typically, stringent conditions will be those in which the salt concentration is less than about 1.0 M sodium ion, typically about 0.01 to 1.0 M sodium ion (or other salts) at pH 7.0 to 8.3 and the temperature is at least about 30°C for short probes, primers or oligonucleotides (e.g., 10 nt to 50 nt) and at least about 60°C for longer probes, primers and oligonucleotides. Stringent conditions may also be achieved with the addition of destabilizing agents, such as formamide.

Stringent conditions are known to those skilled in the art and can be found in CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, N.Y. (1989), 6.3.1-6.3.6. Preferably, the conditions are such that sequences at least about 65%, 70%, 75%, 85%, 90%, 95%, 98%, or 99% homologous to each other typically remain hybridized to each other. A non-limiting example of stringent hybridization conditions is hybridization in a high salt buffer comprising 6X SSC, 50 mM Tris-HCl (pH 7.5), 1 mM EDTA, 0.02% PVP, 0.02% FicoU, 0.02% BSA, and 500 mg/ml denatured salmon sperm DNA at 65°C. This hybridization is followed by one or more washes in 0.2X SSC, 0.01 % BSA at 50°C. An isolated nucleic acid molecule of the invention that hybridizes under stringent conditions to the sequence of SEQ ID NO: l , 3, 5, 7, 9, 1 1 or 13 corresponds to a naturally occurring nucleic acid molecule. As used herein, a "naturally-occurring" nucleic acid molecule refers to an RNA or DNA molecule having a nucleotide sequence that occurs in nature (e.g., encodes a natural protein).

In a second embodiment, a nucleic acid sequence that is hybridizable to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 , 3, 5, 7, 9, 1 1 or 13 , or fragments, analogs or derivatives thereof, under conditions of moderate stringency is provided. A non-limiting example of moderate stringency hybridization conditions are hybridization in 6X SSC, 5X Denhardt's solution, 0.5% SDS and 100 mg/ml denatured salmon sperm DNA at 55°C, followed by one or more washes in IX SSC, 0.1% SDS at 37°C. Other conditions of moderate stringency that may be used are well known in the art. See, e.g., Ausubel et al. ("eds.), 1993, CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, NY, and Kriegler, 1990, GENE TRANSFER AND EXPRESSION, A LABORATORY MANUAL, Stockton Press, NY.

In a third embodiment, a nucleic acid that is hybridizable to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: l, 3, 5, 7, 9, 11 or 13 or fragments, analogs or derivatives thereof, under conditions of low stringency, is provided. A non-limiting example of low stringency hybridization conditions are hybridization in 35% formamide, 5X SSC, 50 mM Tris-HCl (pH 7.5), 5 mM EDTA, 0.02% PVP, 0.02% Ficoll, 0.2% BSA, 100 mg/ml denatured salmon sperm DNA, 10% (wt/vol) dextran sulfate at 40°C, followed by one or more washes in 2X SSC, 25 mM Tris-HCl (pH 7.4), 5 mM EDTA, and 0.1 % SDS at 50°C. Other conditions of low stringency that may be used are well known in the art (e.g., as employed for cross-species hybridizations). See, e.g., Ausubel et al. ('eds.), 1993, CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, NY, and Kriegler, 1990, GENE TRANSFER AND EXPRESSION, A LABORATORY MANUAL, Stockton Press, NY; Shilo and Weinberg, 1981 , Proc Natl Acad Sci USA 78: 6789-6792.

Conservative mutations

In addition to naturally-occurring allelic variants of the GLUTX sequence that may exist in the population, the skilled artisan will further appreciate that changes can be introduced by mutation into the nucleotide sequence of SEQ ID NO: l , 3, 5, 7, 9, 1 1 or 13, thereby leading to changes in the amino acid sequence of the encoded GLUTX protein, without altering the functional ability of the GLUTX protein. For example, nucleotide substitutions leading to amino acid substitutions at "non-essential" amino acid residues can be made in the sequence of SEQ ID NO:l, 3, 5, 7, 9, 11 or 13. A "non-essential" amino acid residue is a residue that can be altered from the wild-type sequence of GLUTX without altering the biological activity, whereas an "essential" amino acid residue is required for biological activity. For example, amino acid residues that are conserved among the GLUTX proteins of the present invention, are predicted to be particularly unamenable to alteration.

In addition, amino acid residues that are conserved among GLUTX members, as indicated by the alignments presented as TABLES 6A through 6E and in FIGS. 1-3, are predicted to be less amenable to alteration. For example, GLUTX proteins of the present invention can contain at least one domain that is a typically conserved region in GLUTX members, i.e., GLUTXl, GLUTX2, or GLUTX3 proteins, and GLUTX homologs. As such, these conserved domains are not likely to be amenable to mutation. Other amino acid residues, however, (e.g., those that are not conserved or only semi-conserved among members of the GLUTX proteins) may not be as essential for activity and thus are more likely to be amenable to alteration.

Another aspect of the invention pertains to nucleic acid molecules encoding GLUTX proteins that contain changes in amino acid residues that are not essential for activity. Such GLUTX proteins differ in amino acid sequence from SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , yet retain biological activity. In one embodiment, the isolated nucleic acid molecule comprises a nucleotide sequence encoding a protein, wherein the protein comprises an amino acid sequence at least about 75% homologous to the amino acid sequence of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21. Preferably, the protein encoded by the nucleic acid is at least about 80% homologous to SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, more preferably at least about 90%, 95%, 98%, and most preferably at least about 99% homologous to SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21.

An isolated nucleic acid molecule encoding a GLUTX protein homologous to the protein of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 can be created by introducing one or more nucleotide substitutions, additions or deletions into the nucleotide sequence of SEQ ID NOT, 3, 5, 7, 9, 1 1 or 13, such that one or more amino acid substitutions, additions or deletions are introduced into the encoded protein.

Mutations can be introduced into SEQ ID NOT, 3, 5, 7, 9, 1 1 or 13 by standard techniques, such as site-directed mutagenesis and PCR-mediated mutagenesis. Preferably, conservative amino acid substitutions are made at one or more predicted non-essential amino acid residues. A "conservative amino acid substitution" is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, mefhionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, a predicted nonessential amino acid residue in GLUTX is replaced with another amino acid residue from the same side chain family. Alternatively, in another embodiment, mutations can be introduced randomly along all or part of a GLUTX coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for GLUTX biological activity to identify mutants that retain activity. Following mutagenesis of SEQ ID NO: l , 3, 5, 7, 9, 1 1 or 13. the encoded protein can be expressed by any recombinant technology known in the art and the activity of the protein can be determined.

In one embodiment, a mutant GLUTX protein can be assayed for (i) the ability to form protein protein interactions with other GLUTX proteins, other cell-surface proteins, or biologically active portions thereof, (ii) complex formation between a mutant GLUTX protein and a GLUTX receptor, (in) the ability of a mutant GLUTX protein to bind to an mtracellular target protein or biologically active portion thereof, (e g , avidin proteins), (iv) the ability to bind BRA protein, or (v) the ability to specifically bind an anti-GLUTX protein antibody

Antisense Another aspect of the invention pertains to isolated antisense nucleic acid molecules that are hybridizable to or complementary to the nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO 1 , 3, 5, 7, 9, 1 1 or 13, or fragments, analogs or derivatives thereof An "antisense" nucleic acid comprises a nucleotide sequence that is complementary to a "sense" nucleic acid encoding a protein, e g , complementary to the coding strand of a double-stranded cDNA molecule or complementary to an mRNA sequence In specific aspects, antisense nucleic acid molecules are provided that comprise a sequence complementary to at least about 10, 25, 50, 100, 250 or 500 nucleotides or an entire GLUTX coding strand, or to only a portion thereof Nucleic acid molecules encoding fragments, homologs, derivatives and analogs of a GLUTX protein of SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , or antisense nucleic acids complementary to a GLUTX nucleic acid sequence of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 are additionally provided

In one embodiment, an antisense nucleic acid molecule is antisense to a "coding region" of the coding strand of a nucleotide sequence encoding GLUTX The term "coding region" refers to the region of the nucleotide sequence comprising codons which are translated into amino acid residues (e g , the protein coding region of human GLUTX corresponds to SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21) In another embodiment, the antisense nucleic acid molecule is antisense to a "noncoding region" of the coding strand of a nucleotide sequence encoding GLUTX The term "noncoding region" refers to 5' and 3' sequences which flank the coding region that are not translated into ammo acids (/ e , also referred to as 5' and 3' untranslated regions)

Given the coding strand sequences encoding GLUTX disclosed herein (e g , SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13 ), antisense nucleic acids of the invention can be designed according to the rules of Watson and Crick or Hoogsteen base pairing The antisense nucleic acid molecule can be complementary to the entire coding region of GLUTX mRNA, but more preferably is an oligonucleotide that is antisense to only a portion of the coding or noncoding region of GLUTX mRNA For example, the antisense oligonucleotide can be complementary to the region surrounding the translation start site of GLUTX mRNA An antisense oligonucleotide can be, for example, about 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 nucleotides in length An antisense nucleic acid of the invention can be constructed using chemical synthesis or enzymatic ligation reactions using procedures known in the art. For example, an antisense nucleic acid (e.g., an antisense oligonucleotide) can be chemically synthesized using naturally occurring nucleotides or variously modified nucleotides designed to increase the biological stability of the molecules or to increase the physical stability of the duplex formed between the antisense and sense nucleic acids, e.g., phosphorothioate derivatives and acridine substituted nucleotides can be used.

Examples of modified nucleotides that can be used to generate the antisense nucleic acid include: 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xanthine, 4-acetylcytosine, 5-(carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl- 2-thiouridine, 5-carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, N6-ιsopentenyladenine, 1-mefhylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine, 5'-methoxycarboxymethyluracil, 5-methoxyuracil, 2-thiocytosine, 5-methyl-2-thiouracil, 2-methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid (v), wybutoxosine, pseudouracil, queosine, 2-thiouracil, 4-thiouracil, 5-methyluracil, uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid (v), 5-methyl-2-thiouracil, N6-adenine, (acp3)w, 2,6-diaminopurine and 3-(3-amino-3-N-2-carboxypropyl) uracil. Alternatively, the antisense nucleic acid can be produced biologically using an expression vector into which a nucleic acid has been subcloned in an antisense orientation (i.e., RNA transcribed from the inserted nucleic acid will be of an antisense orientation to a target nucleic acid of interest, described further in the following subsection).

The antisense nucleic acid molecules of the invention are typically administered to a subject or generated in situ such that they hybridize with or bind to cellular mRNA and/or genomic DNA encoding a GLUTX protein to thereby inhibit expression of the protein, e.g., by inhibiting transcription and/or translation. The hybridization can be by conventional nucleotide complementarity to form a stable duplex, or, for example, in the case of an antisense nucleic acid molecule that binds to DNA duplexes, through specific interactions in the major groove of the double helix. An example of a route of administration of antisense nucleic acid molecules of the invention includes direct injection at a tissue site. Alternatively, antisense nucleic acid molecules can be modified to target selected cells and then administered systemically. For example, for systemic administration, antisense molecules can be modified such that they specifically bind to receptors or antigens expressed on a selected cell surface, e.g., by linking the antisense nucleic acid molecules to peptides or antibodies that bind to cell surface receptors or antigens. The antisense nucleic acid molecules can also be delivered to cells using the vectors described herein. To achieve sufficient mtracellular concentrations of antisense molecules, vector constructs in which the antisense nucleic acid molecule is placed under the control of a strong pol II or pol III promoter are preferred. In yet another embodiment, the antisense nucleic acid molecule of the invention is an α-anomeric nucleic acid molecule. An α-anomeric nucleic acid molecule forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual β-units, the strands run parallel to each other (Gaultier et al. 1987 Nucleic Acids Res 15: 6625-6641). The antisense nucleic acid molecule can also comprise a 2'-o-methylribonucleotide (Inoue et al. 1987 Nucleic Acids Res 15: 6131-6148) or a chimeric RNA-DNA analogue (Inoue et al. 1987 FEBSLett 215: 327-330).

Ribozymes and PNA moieties

Such modifications include, by way of nonlimiting example, modified bases, and nucleic acids whose sugar phosphate backbones are modified or derivatized. These modifications are carried out at least in part to enhance the chemical stability of the modified nucleic acid, such that they may be used, for example, as antisense binding nucleic acids in therapeutic applications in a subject.

In still another embodiment, an antisense nucleic acid of the invention is a ribozyme. Ribozymes are catalytic RNA molecules with ribonuclease activity that are capable of cleaving a single-stranded nucleic acid, such as an mRNA, to which they have a complementary region. Thus, ribozymes (e.g., hammerhead ribozymes (see, e.g., Haselhoff and Gerlach 1988 Nature 334:585-591)) can be used to catalytically cleave GLUTX mRNA transcripts to thereby inhibit translation of GLUTX mRNA. A ribozyme having specificity for a GLUTX-encoding nucleic acid can be designed based upon the nucleotide sequence of a GLUTX DNA disclosed herein (i.e., SEQ ID NOT, 3, 5, 7, 9, 1 1 or 13). For example, a derivative of a Tetrahymena L-19 IVS RNA can be constructed in which the nucleotide sequence of the active site is complementary to the nucleotide sequence to be cleaved in a GLUTX-encoding mRNA. See, e.g., Cech et al. U.S. Pat. No. 4,987,071 ; and Cech et al. U.S. Pat. No. 5,116,742. Alternatively, GLUTX mRNA can be used to select a catalytic RNA having a specific ribonuclease activity from a pool of RNA molecules. See, e.g., Bartel et al. 1993 Science 261 : 1411-1418.

Alternatively, GLUTX gene expression can be inhibited by targeting nucleotide sequences complementary to the regulatory region of the GLUTX (e.g., the GLUTX promoter and/or enhancers) to form triple helical structures that prevent transcription of the GLUTX gene in target cells See generally, Helene 1991 Anticancer Drug Des 6 569-84, Helene. et al 1992 Ann N Y Acad Sci 660 27-36, and Maher 1992 Bwassays 14 807-15

In various embodiments, the nucleic acids of GLUTX can be modified at the base moiety, sugar moiety or phosphate backbone to improve, e g , the stability, hybridization, or solubility of the molecule For example, the deoxyπbose phosphate backbone of the nucleic acids can be modified to generate peptide nucleic acids See, e g , Hyrup et al 1996 Bioorg Med Chem 4 5-23) As used herein, the terms "peptide nucleic acids" or "PNAs" refer to nucleic acid mimics, e g , DNA mimics, in which the deoxyπbose phosphate backbone is replaced by a pseudopeptide backbone and only the four natural nucleobases are retained The neutral backbone of PNAs has been shown to allow for specific hybridization to DNA and RNA under conditions of low ionic strength The synthesis of PNA o gomers can be performed using standard solid phase peptide synthesis protocols See, e g , Hyrup et al (1996) above, Perry-O'Keefe et al 1996 PNAS 93 14670-675

PNAs of GLUTX can be used in therapeutic and diagnostic applications For example, PNAs can be used as antisense or antigene agents for sequence-specific modulation of gene expression by, e g , inducing transcription or translation arrest or inhibiting replication PNAs of GLUTX can also be used, e g , in the analysis of single base pair mutations in a gene by, e g , PNA directed PCR clamping, as artificial restriction enzymes when used in combination with other enzymes, e g , S 1 nucleases, or as probes or pπmers for DNA sequence and hybridization See, e g , Hyrup et al 1996, above, Perry-O'Keefe et al 1996, above)

In another embodiment, PNAs of GLUTX can be modified, e g , to enhance their stability or cellular uptake, by attaching lipophihc or other helper groups to PNA, by the formation of PNA-DNA chimeras, or by the use of hposomes or other techniques of drug delivery known in the art For example, PNA-DNA chimeras of GLUTX can be generated that may combine the advantageous properties of PNA and DNA Such chimeras allow DNA recognition enzymes, e g , RNase H and DNA polymerases, to interact with the DNA portion while the PNA portion would provide high binding affinity and specificity PNA-DNA chimeras can be linked using linkers of appropriate lengths selected in terms of base stacking, number of bonds between the nucleobases, and orientation See, e g , Hyrup et al 1996, above The PNA-DNA chimeras can be synthesized See, e g , Hyrup et al 1996, above, and Finn et al 1996 Nucl Acids Res 24 3357-63 For example, a DNA chain can be synthesized on a solid support using standard phosphoramidite coupling chemistry, and modified nucleoside analogs, e g , 5'-(4-methoxytπtyl) ammo-5'-deoxy-thymιdιne phosphoramidite, can be used between the PNA and the 5' end of DNA See, e g , Mag et al 1989 Nucl Acid Res 17 5973-88. PNA monomers are then coupled in a stepwise manner to produce a chimeric molecule with a 5' PNA segment and a 3' DNA segment. See, e.g., Finn et al. 1996, above. Alternatively, chimeric molecules can be synthesized with a 5' DNA segment and a 3' PNA segment. See, e.g., Petersen et al. 1975 Bioorg Med Chem Lett 5: 1119-11 124. In other embodiments, the oligonucleotide may include other appended groups such as peptides (e.g., for targeting host cell receptors in vivo), or agents facilitating transport across the cell membrane (see, e.g., Letsinger et al., 1989, Proc. Natl. Acad. Sci. U.S.A. 86:6553-6556; Lemaitre et al, 1987, Proc. Natl. Acad. Sci. 84:648-652; PCT Publication No. W088/09810) or the blood-brain barrier (see, e.g., PCT Publication No. W089/10134). In addition, oligonucleotides can be modified with hybridization triggered cleavage agents (see, e.g., Krol et al, 1988, BioTechniques 6:958-976) or intercalating agents (see, e.g., Zon, 1988, Pharm. Res. 5: 539-549). To this end, the oligonucleotide may be conjugated to another molecule, e.g., a peptide, a hybridization triggered cross-linking agent, a transport agent, a hybridization-triggered cleavage agent, etc.

GLUTX polypeptides

The novel protein of the invention includes the GLUTX-like protein whose sequence is provided in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21. The invention also includes a mutant or variant protein any of whose residues may be changed from the corresponding residue shown in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 while still encoding a protein that maintains its GLUTX-like activities and physiological functions, or a functional fragment thereof. In the mutant or variant protein, up to 20% or more of the residues may be so changed.

In general, an GLUTX -like variant that preserves GLUTX-like function includes any variant in which residues at a particular position in the sequence have been substituted by other amino acids, and further include the possibility of inserting an additional residue or residues between two residues of the parent protein as well as the possibility of deleting one or more residues from the parent sequence. Any amino acid substitution, insertion, or deletion is encompassed by the invention. In favorable circumstances, the substitution is a conservative substitution as defined above. In other embodiments, the substitutions are at non-conserved positions, as described by dashes (-) or lower case letters in the Tables in the EXAMPLES. One aspect of the invention pertains to isolated GLUTX proteins, and biologically active portions thereof, or derivatives, fragments, analogs or homologs thereof. Also provided are polypeptide fragments suitable for use as immunogens to raise anti-GLUTX antibodies. In one embodiment, native GLUTX proteins can be isolated from cells or tissue sources by an appropriate purification scheme using standard protein purification techniques. In another embodiment, GLUTX proteins are produced by recombinant DNA techniques. Alternative to recombinant expression, a GLUTX protein or polypeptide can be synthesized chemically using standard peptide synthesis techniques.

An "isolated" or "purified" protein or biologically active portion thereof is substantially free of cellular material or other contaminating proteins from the cell or tissue source from which the GLUTX protein is derived, or substantially free from chemical precursors or other chemicals when chemically synthesized. The language "substantially free of cellular material" includes preparations of GLUTX protein in which the protein is separated from cellular components of the cells from which it is isolated or recombinantly produced. In one embodiment, the language "substantially free of cellular material" includes preparations of GLUTX protein having less than about 30% (by dry weight) of non-GLUTX protein (also referred to herein as a "contaminating protein"), more preferably less than about 20% of non-GLUTX protein, still more preferably less than about 10% of non-GLUTX protein, and most preferably less than about 5% non-GLUTX protein. When the GLUTX protein or biologically active portion thereof is recombinantly produced, it is also preferably substantially free of culture medium, i.e., culture medium represents less than about 20%, more preferably less than about 10%, and most preferably less than about 5% of the volume of the protein preparation.

The language "substantially free of chemical precursors or other chemicals" includes preparations of GLUTX protein in which the protein is separated from chemical precursors or other chemicals that are involved in the synthesis of the protein. In one embodiment, the language "substantially free of chemical precursors or other chemicals" includes preparations of GLUTX protein having less than about 30%) (by dry weight) of chemical precursors or non-GLUTX chemicals, more preferably less than about 20% chemical precursors or non-GLUTX chemicals, still more preferably less than about 10% chemical precursors or non-GLUTX chemicals, and most preferably less than about 5% chemical precursors or non-GLUTX chemicals. Biologically active portions of a GLUTX protein include peptides comprising amino acid sequences sufficiently homologous to or derived from the amino acid sequence of the GLUTX protein, e.g., the amino acid sequence shown in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 that include fewer amino acids than the full length GLUTX proteins, and exhibit at least one activity of a GLUTX protein. Typically, biologically active portions comprise a domain or motif with at least one activity of the GLUTX protein. A biologically active portion of a GLUTX protein can be a polypeptide which is, for example, 10, 25, 50, 100 or more amino acids in length.

A biologically active portion of a GLUTX protein of the present invention may contain at least one of the above-identified domains conserved between the GLUTX proteins.

Moreover, other biologically active portions, in which other regions of the protein are deleted, can be prepared by recombinant techniques and evaluated for one or more of the functional activities of a native GLUTX protein.

In an embodiment, the GLUTX protein has an amino acid sequence shown in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21. In other embodiments, the GLUTX protein is substantially homologous to SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 and retains the functional activity of the protein of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, yet differs in amino acid sequence due to natural allelic variation or mutagenesis, as described in detail below. Accordingly, in another embodiment, the GLUTX protein is a protein that comprises an amino acid sequence at least about 45% homologous to the amino acid sequence of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 and retains the functional activity of the GLUTX proteins of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21.

Determining homology between two or more sequences To determine the percent homology of two amino acid sequences or of two nucleic acids, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in either of the sequences being compared for optimal alignment between the sequences). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are homologous at that position (i.e., as used herein amino acid or nucleic acid "homology" is equivalent to amino acid or nucleic acid "identity").

The nucleic acid sequence homology may be determined as the degree of identity between two sequences. The homology may be determined using computer programs known in the art, such as GAP software provided in the GCG program package. See, Needleman and Wunsch 1970 J Mol Biol 48: 443-453. Using GCG GAP software with the following settings for nucleic acid sequence comparison: GAP creation penalty of 5.0 and GAP extension penalty of 0.3, the coding region of the analogous nucleic acid sequences referred to above exhibits a degree of identity preferably of at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99%, with the CDS (encoding) part of the DNA sequence shown in SEQ ID NO 1, 3, 5, 7, 9, 11 or 13

The term "sequence identity" refers to the degree to which two polynucleotide or polypeptide sequences are identical on a residue-by-residue basis over a particular region of comparison The term "percentage of sequence identity" is calculated by comparing two optimally aligned sequences over that region of comparison, determining the number of positions at which the identical nucleic acid base (e g , A, T, C, G, U, or I, in the case of nucleic acids) occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the region of comparison (i e , the window size), and multiplying the result by 100 to yield the percentage of sequence identity The term "substantial identity" as used herein denotes a characteristic of a polynucleotide sequence, wherein the polynucleotide comprises a sequence that has at least 80 percent sequence identity, preferably at least 85 percent identity and often 90 to 95 percent sequence identity, more usually at least 99 percent sequence identity as compared to a reference sequence over a comparison region The term "percentage of positive residues" is calculated by comparing two optimally aligned sequences over that region of comparison, determining the number of positions at which the identical and conservative amino acid substitutions, as defined above, occur in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the region of comparison (i e , the window size), and multiplying the result by 100 to yield the percentage of positive residues

Chimeric and fusion proteins

The invention also provides GLUTX chimeric or fusion proteins As used herein, a GLUTX "chimeric protein" or "fusion protein" comprises a GLUTX polypeptide operatively linked to a non-GLUTX polypeptide A "GLUTX polypeptide" refers to a polypeptide having an amino acid sequence corresponding to GLUTX, whereas a "non-GLUTX polypeptide" refers to a polypeptide having an amino acid sequence corresponding to a protein that is not substantially homologous to the GLUTX protein, e g , a protein that is different from the GLUTX protein and that is derived from the same or a different organism Within a GLUTX fusion protein the GLUTX polypeptide can correspond to all or a portion of a GLUTX protein In one embodiment, a GLUTX fusion protein comprises at least one biologically active portion of a GLUTX protein In another embodiment, a GLUTX fusion protein comprises at least two biologically active portions of a GLUTX protein Within the fusion protein, the term "operatively linked" is intended to indicate that the GLUTX polypeptide and the non-GLUTX polypeptide are fused in-frame to each other The non-GLUTX polypeptide can be fused to the N-terminus or C -terminus of the GLUTX polypeptide

For example, in one embodiment a GLUTX fusion protein comprises a GLUTX polypeptide operably linked to the extracellular domain of a second protein Such fusion proteins can be further utilized in screening assays for compounds that modulate GLUTX activity (such assays are described in detail below)

In another embodiment, the fusion protein is a GST-GLUTX fusion protein in which the GLUTX sequences are fused to the C-terminus of the GST (/ e , glutathione S-transferase) sequences Such fusion proteins can facilitate the purification of recombinant GLUTX In yet another embodiment, the fusion protein is a GLUTX protein containing a heterologous signal sequence at its N-terminus For example, the native GLUTX signal sequence (i e , amino acids 1 to 20 of SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21) can be removed and replaced with a signal sequence from another protein In certain host cells (e g , mammalian host cells), expression and/or secretion of GLUTX can be increased through use of a heterologous signal sequence

In another embodiment, the fusion protein is a GLUTX-immunoglobuhn fusion protein in which the GLUTX sequences comprising one or more domains are fused to sequences derived from a member of the immunoglobuhn protein family The GLUTX-immunoglobuhn fusion proteins of the invention can be incorporated into phaπnaceutical compositions and administered to a subject to inhibit an interaction between a GLUTX ligand and a GLUTX protein on the surface of a cell, to thereby suppress GLUTX-mediated signal transduction in vivo In one nonhmiting example, a contemplated GLUTX ligand of the invention is the GLUTX receptor The GLUTX-immunoglobuhn fusion proteins can be used to affect the bioavailabihty of a GLUTX cognate ligand Inhibition of the GLUTX hgand/GLUTX interaction may be useful therapeutically for both the treatment of prohferative and differentiative disorders, as well as modulating (e g , promoting or inhibiting) cell survival Moreover, the GLUTX-immunoglobuhn fusion proteins of the invention can be used as immunogens to produce anti-GLUTX antibodies m a subject, to purify GLUTX ligands, and in screening assays to identify molecules that inhibit the interaction of GLUTX with a GLUTX ligand

A GLUTX chimeric or fusion protein of the invention can be produced by standard recombinant DNA techniques For example, DNA fragments coding for the different polypeptide sequences are ligated together m-frame m accordance with conventional techniques, e g , by employing blunt-ended or stagger-ended termini for hgation, restπction enzyme digestion to provide for appropriate termini, filling-in of cohesive ends as appropπate, alkaline phosphatase treatment to avoid undesirable joining, and enzymatic hgation In another embodiment, the fusion gene can be synthesized by conventional techniques including automated DNA synthesizeis Alternatively, PCR amplification of gene fragments can be carried out using anchor primers that give rise to complementary overhangs between two consecutive gene fragments that can subsequently be annealed and reamphfied to generate a chimeric gene sequence (see, for example, Ausubel et al (eds ) CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, 1992) Moreover, many expression vectors are commercially available that already encode a fusion moiety (e g , a GST polypeptide) A GLUTX-encoding nucleic acid can be cloned into such an expression vector such that the fusion moiety is linked in-frame to the GLUTX protein

GLUTX agonists and antagonists

The present invention also pertains to variants of the GLUTX proteins that function as either GLUTX agonists (mimetics) or as GLUTX antagonists Variants of the GLUTX protein can be generated by mutagenesis, e g , discrete point mutation or truncation of the GLUTX protein An agonist of the GLUTX protein can retain substantially the same, or a subset of, the biological activities of the naturally occurring form of the GLUTX protein An antagonist of the GLUTX protein can inhibit one or more of the activities of the naturally occurring form of the GLUTX protein by, for example, competitively binding to a downstream or upstream member of a cellular signaling cascade which includes the GLUTX protein Thus, specific biological effects can be elicited by treatment with a variant of limited function In one embodiment, tiealment of a subject with a

ιng a subset of the biological activities of the naturally occurring form of the protein has fewer side effects in a subject relative to treatment with the naturally occurring form of the GLUTX proteins Variants of the GLUTX protein that function as either GLUTX agonists (mimetics) or as GLUTX antagonists can be identified by screening combinatorial libraries of mutants, e g , truncation mutants, of the GLUTX protein for GLUTX protein agonist or antagonist activity In one embodiment, a variegated library of GLUTX variants is generated by combinatorial mutagenesis at the nucleic acid level and is encoded by a variegated gene library A variegated library of GLUTX variants can be produced by, for example, enzymatically hgatmg a mixture of synthetic oligonucleotides into gene sequences such that a degenerate set of potential GLUTX sequences is expressible as individual polypeptides, or alternatively, as a set of larger fusion proteins (e g , for phage display) containing the set of GLUTX sequences therein There are a variety of methods which can be used to produce libraries of potential GLUTX variants from a degenerate oligonucleotide sequence Chemical synthesis of a degenerate gene sequence can be performed in an automatic DNA synthesizer, and the synthetic gene then ligated into an appropriate expression vector Use of a degenerate set of genes allows for the provision, in one mixture, of all of the sequences encoding the desired set of potential GLUTX sequences Methods for synthesizing degenerate oligonucleotides are known in the art (see, e g , Narang (1983) Tetrahedron 39 3, Itakura et al (\9%A) Annu Rev Biochem 53 323, Itakura et al (1984) Science 198 1056, Ike et al (1983) Nucl Acid Res 1 1 477

Polypeptide libraries In addition, libraries of fragments of the GLUTX protein coding sequence can be used to generate a variegated population of GLUTX fragments for screening and subsequent selection of variants of a GLUTX protein In one embodiment, a library of coding sequence fragments can be generated by treating a double stranded PCR fragment of a GLUTX coding sequence with a nuclease under conditions wherein nicking occurs only about once per molecule, denaturing the double stranded DNA, renatuπng the DNA to form double stranded DNA that can include sense/ antisense pairs from different nicked products, removing single stranded portions from reformed duplexes by treatment with SI nuclease, and ligatmg the resulting fragment library into an expression vector By this method, an expression library can be derived which encodes N-terminal and internal fragments of various sizes of the GLUTX protein

Several techniques are known in the art foi screening gene products of combinatorial libraries made by point mutations or truncation, and for screening cDNA libraries for gene products having a selected property Such techniques are adaptable for rapid screening of the gene libraries generated by the combinatorial mutagenesis of GLUTX proteins The most widely used techniques, which are amenable to high throughput analysis, for screening large gene libraries typically include cloning the gene library into rephcable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the combinatorial genes under conditions in which detection of a desired activity facilitates isolation of the vector encoding the gene whose product was detected Recrusive ensemble mutagenesis (REM), a new technique that enhances the frequency of functional mutants m the libraries, can be used in combination with the screening assays to identify GLUTX variants (Arkin and Yourvan 1992 PNAS 89 781 1-7815, Delgrave et al 1993 Protein Engineering 6 327-331) Anti-GLUTX Antibodies

The invention further encompasses antibodies and antibody fragments, such as F_ab or (F_ab . that bind immunospecifically to any of the proteins of the invention.

An isolated GLUTX protein, or a portion or fragment thereof, can be used as an immunogen to generate antibodies that bind GLUTX using standard techniques for polyclonal and monoclonal antibody preparation. Full-length GLUTX protein can be used. Alternatively, the invention provides antigenic peptide fragments of GLUTX for use as immunogens. The antigenic peptide of GLUTX comprises at least 4 amino acid residues of the amino acid sequence shown in SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21. The antigenic peptide encompasses an epitope of GLUTX such that an antibody raised against the peptide forms a specific immune complex with GLUTX. The antigenic peptide may comprise at least 6 aa residues, at least 8 aa residues, at least 10 aa residues, at least 15 aa residues, at least 20 aa residues, or at least 30 aa residues. In one embodiment of the invention, the antigenic peptide comprises a polypeptide comprising at least 6 contiguous amino acids of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21.

In an embodiment of the invention, epitopes encompassed by the antigenic peptide are regions of GLUTX that are located on the surface of the protein, e.g., hydrophilic regions. A hydrophobicity analysis of the human GLUTX protein sequence would indicate that the regions between the TM domains are particularly hydrophilic and, therefore, are likely to encode surface residues useful for targeting antibody production. As a means for targeting antibody production, hydropathy plots showing regions of hydrophilicity and hydrophobicity may be generated by any method well known in the art, including, for example, the Kyte Doolittle or the Hopp Woods methods, either with or without Fourier transformation. See, e.g., Hopp and Woods, 1981 , Proc. Nat. Acad. Sci. USA 78: 3824-3828; Kyte and Doolittle 1982, J. Mol. Biol. 157: 105-142, each incorporated herein by reference in their entirety.

As disclosed herein, GLUTX protein sequence of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , or derivatives, fragments, analogs or homologs thereof, may be utilized as immunogens in the generation of antibodies that immunospecifically-bind these protein components. The teπu "antibody" as used herein refers to immunoglobuhn molecules and immunologically active portions of immunoglobuhn molecules, i.e., molecules that contain an antigen binding site that specifically binds (immunoreacts with) an antigen, such as GLUTX. Such antibodies include, but are not limited to, polyclonal, monoclonal, chimeric, single chain, F_ab and F_(ab'₎₂ fragments, and an F_ab expression library. In a specific embodiment, antibodies to human GLUTX proteins are disclosed. Various procedures known within the art may be used for the production of polyclonal or monoclonal antibodies to a GLUTX protein sequence of SEQ ID NO:2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, or a derivative, fragment, analog or homolog thereof. Some of these proteins are discussed below.

For the production of polyclonal antibodies, various suitable host animals (e.g., rabbit, goat, mouse or other mammal) may be immunized by injection with the native protein, or a synthetic variant thereof, or a derivative of the foregoing. An appropriate immunogenic preparation can contain, for example, recombinantly expressed GLUTX protein or a chemically synthesized GLUTX polypeptide. The preparation can further include an adjuvant. Various adjuvants used to increase the immunological response include, but are not limited to, Freund's (complete and incomplete), mineral gels (e.g., aluminum hydroxide), surface active substances (e.g., lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, dinitrophenol, etc.), human adjuvants such as Bacille Calmette-Guerin and Corynebacterium parvum, or similar immunostimulatory agents. If desired, the antibody molecules directed against GLUTX can be isolated from the mammal (e.g., from the blood) and further purified by well known techniques, such as protein A chromatography to obtain the IgG fraction. The term "monoclonal antibody" or "monoclonal antibody composition", as used herein, refers to a population of antibody molecules that contain only one species of an antigen binding site capable of immunoreacting with a particular epitope of GLUTX. A monoclonal antibody composition thus typically displays a single binding affinity for a particular GLUTX protein with which it immunoreacts. For preparation of monoclonal antibodies directed towards a particular GLUTX protein, or derivatives, fragments, analogs or homologs thereof, any technique that provides for the production of antibody molecules by continuous cell line culture may be utilized. Such techniques include, but are not limited to, the hybridoma technique (see Kohler & Milstein, 1975 Nature 256: 495-497); the trioma technique; the human B-cell hybridoma technique (see Kozbor, et al, 1983 Immunol Today 4: 72) and the

EBV hybridoma technique to produce human monoclonal antibodies (see Cole, et al, 1985 In: MONOCLONAL ANTIBODIES AND CANCER THERAPY, Alan R. Liss, Inc., pp. 77-96). Human monoclonal antibodies may be utilized in the practice of the present invention and may be produced by using human hybridomas (see Cote, et al, 1983. Proc Natl Acad Sci USA 80: 2026-2030) or by transforming human B-cells with Epstein Barr Virus in vitro (see Cole, et al, 1985 In: MONOCLONAL ANTIBODIES AND CANCER THERAPY, Alan R. Liss, Inc., pp. 77-96). Each of the above citations are incorporated herein by reference in their entirety.

According to the invention, techniques can be adapted for the production of single-chain antibodies specific to a GLUTX protein (see e.g., U.S. Patent No. 4,946,778). In addition, methods can be adapted for the construction of F_ab expression libraries (see e.g.,

Huse, et al, 1989 Science 246: 1275-1281) to allow rapid and effective identification of monoclonal F_ab fragments with the desired specificity for a GLUTX protein or derivatives, fragments, analogs or homologs thereof. Non-human antibodies can be "humanized" by techniques well known in the art. See e.g., U.S. Patent No. 5,225,539. Each of the above citations are incorporated herein by reference. Antibody fragments that contain the idiotypes to a GLUTX protein may be produced by techniques known in the art including, but not limited to: ( ) an F(_ab')₂ fragment produced by pepsin digestion of an antibody molecule; (ii) an F_ab fragment generated by reducing the disulfide bridges of an F_(ab'₎₂ fragment; (Hi) an F_ab fragment generated by the treatment of the antibody molecule with papain and a reducing agent and (iv) F_v fragments.

Additionally, recombinant anti-GLUTX antibodies, such as chimeric and humanized monoclonal antibodies, comprising both human and non-human portions, which can be made using standard recombinant DNA techniques, are within the scope of the invention. Such chimeric and humanized monoclonal antibodies can be produced by recombinant DNA techniques known in the art, for example using methods described in PCT International Application No. PCT/US86/02269; European Patent Application No. 184,187; European Patent Application No. 171 ,496; European Patent Application No. 173,494; PCT International Publication No. WO 86/01533; U.S. Pat. No. 4,816,567; European Patent Application No. 125,023; Better et α/.(1988) Science 240:1041-1043; Liu et al. (1987) PNAS 84:3439-3443; Uu et al (1987) J Immunol. 139:3521-3526; Sun et al (1987) PNAS 84:214-218; Nishimura et al (1987) Cancer Res 47:999-1005; Wood et al. (1985) Nature 314:446-449; Shaw et al. (1988), J. Natl Cancer Inst 80:1553-1559); Morrison(1985) Science 229:1202-1207; Oi et al. (1986) BioTechniques 4:214; U.S. Pat. No. 5,225,539; Jones et al. (1986) Nature 321 :552-525; Verhoeyan el al (1988) Science 239: 1534; and Beidler et al (1988) J Immunol 141 :4053-4060. Each of the above citations are incorporated herein by reference.

In one embodiment, methods for the screening of antibodies that possess the desired specificity include, but are not limited to, enzyme-linked immunosorbent assay (ELISA) and other immunologically-mediated techniques known within the art. In a specific embodiment, selection of antibodies that are specific to a particular domain of a GLUTX protein is facilitated by generation of hybridomas that bind to the fragment of a GLUTX protein possessing such a domain. Antibodies that are specific for one or more domains within a GLUTX protein, e.g., any one or more of the cytoplasmic or extracellular loop regions between the TM domains, specific to GLUTX family member, GLUTXl, GLUTX2 or GLUTX3 when compared to GLUT 1-5, or derivatives, fragments, analogs or homologs thereof, are also provided herein

Anti-GLUTX antibodies may be used in methods known withm the art relating to the localization and/or quantitation of a GLUTX protein (e g , for use in measuring levels of the GLUTX protein within appropriate physiological samples, for use in diagnostic methods, for use in imaging the protein, and the like) In a given embodiment, antibodies for GLUTX proteins, or derivatives, fragments, analogs or homologs thereof, that contain the antibody derived binding domain, are utilized as pharmacologically-active compounds [hereinafter "Therapeutics"] An anti-GLUTX antibody (e g , monoclonal antibody) can be used to isolate GLUTX by standard techniques, such as affinity chromatography or immunoprecipitation An anti-GLUTX antibody can facilitate the purification of natural GLUTX from cells and of recombinantly produced GLUTX expressed in host cells Moreover, an anti-GLUTX antibody can be used to detect GLUTX protein (e g , in a cellular lysate or cell supernatant) in order to evaluate the abundance and pattern of expression of the GLUTX protein Anti-GLUTX antibodies can be used diagnostically to monitor protein levels in tissue as part of a clinical testing procedure, e g , to, for example, determine the efficacy of a given treatment regimen Detection can be facilitated by coupling (/ e , physically linking) the antibody to a detectable substance Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent mateπals, biolummescent materials, and radioactive materials Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, β-galactosidase, or acetylchohnesterase, examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotm, examples of suitable fluorescent materials include umbelhferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotπazinylamme fluorescein, dansyl chloride or phycoerythrin, an example of a luminescent material includes luminol, examples of biolummescent materials include luciferase, luciferm, and aequoπn, and examples of suitable radioactive material include I, ¹³¹I, ³⁵S or ³H

GLUTX Recombinant Expression Vectors and Host Cells Another aspect of the invention pertains to vectors, preferably expression vectors, containing a nucleic acid encoding GLUTX protein, or derivatives, fragments, analogs or homologs thereof As used herein, the term "vector" refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked One type of vector is a

"plasmid", which refers to a circular double stranded DNA loop into which additional DNA segments can be ligated. Another type of vector is a viral vector, wherein additional DNA segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as "expression vectors". In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, "plasmid" and "vector" can be used interchangeably as the plasmid is the most commonly used form of vector. However, the invention is intended to include such other forms of expression vectors, such as viral vectors (e.g., replication defective retroviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions. The recombinant expression vectors of the invention comprise a nucleic acid of the invention in a form suitable for expression of the nucleic acid in a host cell, which means that the recombinant expression vectors include one or more regulatory sequences, selected on the basis of the host cells to be used for expression, that is operatively linked to the nucleic acid sequence to be expressed. Within a recombinant expression vector, "operably linked" is intended to mean that the nucleotide sequence of interest is linked to the regulatory sequence(s) in a manner that allows for expression of the nucleotide sequence (e.g., in an in vitro transcription/translation system or in a host cell when the vector is introduced into the host cell). The term "regulatory sequence" is intended to includes promoters, enhancers and other expression control elements (e.g., polyadenylation signals). Such regulatory sequences are described, for example, in Goeddel; GENE EXPRESSION TECHNOLOGY: METHODS IN ENZYMOLOGY 185, Academic Press, San Diego, Calif. (1990). Regulatory sequences include those that direct constitutive expression of a nucleotide sequence in many types of host cell and those that direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the host cell to be transformed, the level of expression of protein desired, etc. The expression vectors of the invention can be introduced into host cells to thereby produce proteins or peptides, including fusion proteins or peptides, encoded by nucleic acids as described herein (e.g. , GLUTX proteins, mutant forms of GLUTX, fusion proteins, etc.). The recombinant expression vectors of the invention can be designed for expression of

GLUTX in prokaryotic or eukaryotic cells For example, GLUTX can be expressed in bacterial cells such as E coli, insect cells (using baculovirus expression vectors) yeast cells or mammalian cells Suitable host cells are discussed further in Goeddel, GENE EXPRESSION TECHNOLOGY METHODS IN ENZYMOLOGY 185, Academic Press, San Diego, Calif (1990)

Alternatively, the recombinant expression vector can be transcribed and translated in vitro, for example using T7 promoter regulatory sequences and T7 polymerase

Expression of proteins in prokaryotes is most often carried out in E coli with vectors containing constitutive or inducible promoters directing the expression of either fusion or non-fusion proteins Fusion vectors add a number of amino acids to a protein encoded therein, usually to the ammo terminus of the recombinant protein Such fusion vectors typically serve three purposes (1 ) to increase expression of recombinant protein, (2) to increase the solubility of the recombinant protein, and (3) to aid in the purification of the recombinant protein by acting as a ligand in affinity purification Often, in fusion expression vectors, a proteolytic cleavage site is introduced at the junction of the fusion moiety and the recombinant protein to enable separation of the recombinant protein from the fusion moiety subsequent to purification of the fusion protein Such enzymes, and their cognate recognition sequences, include Factor Xa, thrombin and enterokinase Typical fusion expression vectors include pGEX (Pharmacia Biotech Inc, Smith and Johnson (1988) Gene 67 31-40), pMAL (New England Biolabs, Beverly, Mass ) and pRIT5 (Pharmacia, Piscataway, N J ) that fuse glutathione S-transferase (GST), maltose E binding protein, or protein A, respectively, to the target recombinant protein

Examples of suitable inducible non-fusion E coli expression vectors include pTrc (Amrann et al , (1988) Gene 69 301-315) and pET l id (Studier et al , GENE EXPRESSION TECHNOLOGY METHODS IN ENZYMOLOGY 185, Academic Press, San Diego, Calif (1990) 60-89)

One strategy to maximize recombinant protein expression in E coli is to express the protein in a host bacteria with an impaired capacity to proteolytically cleave the recombinant protein See, Gottesman, GENE EXPRESSION TECHNOLOGY METHODS IN ENZYMOLOGY 185, Academic Press, San Diego, Calif (1990) 1 19-128 Another strategy is to alter the nucleic acid sequence of the nucleic acid to be inserted into an expression vector so that the individual codons for each ammo acid are those preferentially utilized in E coli (Wada et al , (1992) Nucleic Acids Res 20 21 1 1-21 18) Such alteration of nucleic acid sequences of the invention can be carried out by standard DNA synthesis techniques In another embodiment, the GLUTX expression vector is a yeast expression vector.

Examples of vectors for expression in yeast S. cerivisae include pYepSecl (Baldari, et al, (1987) EMBO J 6:229-234), pMFa (Kurjan and Herskowitz, (1982) Cell 30:933-943), pJRY88 (Schultz et al, (1987) Gene 54: 113-123), pYES2 (Invitrogen Corporation, San Diego, Calif), and picZ (InVitrogen Corp, San Diego, Calif).

Alternatively, GLUTX can be expressed in insect cells using baculovirus expression vectors. Baculovirus vectors available for expression of proteins in cultured insect cells (e.g., SF9 cells) include the pAc series (Smith et al (1983) Mol Cell Biol 3:2156-2165) and the pVL series (Lucklow and Summers (1989) Virology 170:31-39). In yet another embodiment, a nucleic acid of the invention is expressed in mammalian cells using a mammalian expression vector. Examples of mammalian expression vectors include pCDM8 (Seed (1987) Nature 329:840) and pMT2PC (Kaufman et al. (1987) EMBO J 6: 187-195). When used in mammalian cells, the expression vector's control functions are often provided by viral regulatory elements. For example, commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40. For other suitable expression systems for both prokaryotic and eukaryotic cells. See, e.g., Chapters 16 and 17 of Sambrook et al, MOLECULAR CLONING: A LABORATORY MANUAL. 2nd ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989. In another embodiment, the recombinant mammalian expression vector is capable of directing expression of the nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid). Tissue-specific regulatory elements are known in the art. Non-limiting examples of suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al. (1987) Genes Dev 1 :268-277), lymphoid-specific promoters (Calame and Eaton (1988) Adv Immunol

43:235-275), in particular promoters of T cell receptors (Winoto and Baltimore (1989) EMBO J 8:729-733) and immunoglobulins (Banerji et al. (1983) Cell 33:729-740; Queen and Baltimore (1983) Cell 33:741-748), neuron-specific promoters (e.g., the neurofilament promoter; Byrne and Ruddle (1989) PNAS 86:5473-5477), pancreas-specific promoters (Edlund et al. (1985) Science 230:912-916), and mammary gland-specific promoters (e.g., milk whey promoter; U.S. Pat. No. 4,873,316 and European Application Publication No. 264,166). Developmentally-regulated promoters are also encompassed, e.g., the murine hox promoters (Kessel and Gruss (1990) Science 249:374-379) and the α-fetoprotein promoter (Campes and Tilghman (1989) Genes Dev 3:537-546). The invention further provides a recombinant expression vector comprising a DNA molecule of the invention cloned into the expression vector in an antisense orientation. That is, the DNA molecule is operatively linked to a regulatory sequence in a manner that allows for expression (by transcription of the DNA molecule) of an RNA molecule that is antisense to GLUTX mRNA. Regulatory sequences operatively linked to a nucleic acid cloned in the antisense orientation can be chosen that direct the continuous expression of the antisense RNA molecule in a variety of cell types, for instance viral promoters and/or enhancers, or regulatory sequences can be chosen that direct constitutive, tissue specific or cell type specific expression of antisense RNA. The antisense expression vector can be in the form of a recombinant plasmid, phagemid or attenuated virus in which antisense nucleic acids are produced under the control of a high efficiency regulatory region, the activity of which can be determined by the cell type into which the vector is introduced. For a discussion of the regulation of gene expression using antisense genes see Weintraub et al, "Antisense RNA as a molecular tool for genetic analysis," Reviews—Trends in Genetics, Vol. 1 (1) 1986. Another aspect of the invention pertains to host cells into which a recombinant expression vector of the invention has been introduced. The terms "host cell" and "recombinant host cell" are used interchangeably herein. It is understood that such terms refer not only to the particular subject cell but to the progeny or potential progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term as used herein.

A host cell can be any prokaryotic or eukaryotic cell. For example, GLUTX protein can be expressed in bacterial cells such as E. coli, insect cells, yeast or mammalian cells (such as Chinese hamster ovary cells (CHO) or COS cells). Other suitable host cells are known to those skilled in the art.

Vector DNA can be introduced into prokaryotic or eukaryotic cells via conventional transformation or transfection techniques. As used herein, the terms "transformation" and "transfection" are intended to refer to a variety of art-recognized techniques for introducing foreign nucleic acid (e.g., DNA) into a host cell, including calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, or electroporation. Suitable methods for transforming or transfecting host cells can be found in Sambrook, et al. (MOLECULAR CLONING: A LABORATORY MANUAL. 2nd ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989), and other laboratory manuals. For stable transfection of mammalian cells, it is known that, depending upon the expression vector and transfection technique used, only a small fraction of cells may integrate the foreign DNA into their genome. In order to identify and select these integrants, a gene that encodes a selectable marker (e.g., resistance to antibiotics) is generally introduced into the host cells along with the gene of interest. Various selectable markers include those that confer resistance to drugs, such as G418, hygromycin and methotrexate. Nucleic acid encoding a selectable marker can be introduced into a host cell on the same vector as that encoding GLUTX or can be introduced on a separate vector. Cells stably transfected with the introduced nucleic acid can be identified by drug selection (e.g., cells that have incorporated the selectable marker gene will survive, while the other cells die).

A host cell of the invention, such as a prokaryotic or eukaryotic host cell in culture, can be used to produce (i.e., express) GLUTX protein. Accordingly, the invention further provides methods for producing GLUTX protein using the host cells of the invention. In one embodiment, the method comprises culturing the host cell of invention (into which a recombinant expression vector encoding GLUTX has been introduced) in a suitable medium such that GLUTX protein is produced. In another embodiment, the method further comprises isolating GLUTX from the medium or the host cell.

Transgenic animals

The host cells of the invention can also be used to produce nonhuman transgenic animals. For example, in one embodiment, a host cell of the invention is a fertilized oocyte or an embryonic stem cell into which GLUTX-coding sequences have been introduced. Such host cells can then be used to create non-human transgenic animals in which exogenous GLUTX sequences have been introduced into their genome or homologous recombinant animals in which endogenous GLUTX sequences have been altered. Such animals are useful for studying the function and/or activity of GLUTX and for identifying and/or evaluating modulators of GLUTX activity. As used herein, a "transgenic animal" is a non-human animal, preferably a mammal, more preferably a rodent such as a rat or mouse, in which one or more of the cells of the animal includes a transgene. Other examples of transgenic animals include non-human primates, sheep, dogs, cows, goats, chickens, amphibians, etc. A transgene is exogenous DNA that is integrated into the genome of a cell from which a transgenic animal develops and that remains in the genome of the mature animal, thereby directing the expression of an encoded gene product in one or more cell types or tissues of the transgenic animal. As used herein, a "homologous recombinant animal" is a non-human animal, preferably a mammal, more preferably a mouse, in which an endogenous GLUTX gene has been altered by homologous recombination between the endogenous gene and an exogenous

DNA molecule introduced into a cell of the animal, e g , an embryonic cell of the animal, pπor to development of the animal

A transgenic animal of the invention can be created by introducing GLUTX-encoding nucleic acid into the male pronuclei of a fertilized oocyte, e g , by microinjection, retroviral infection, and allowing the oocyte to develop in a pseudopregnant female foster animal The human GLUTX DNA sequence of SEQ ID NO 1, 3, 5, 7, 9, 11 or 13 can be introduced as a transgene into the genome of a non-human animal Alternatively, a nonhuman homologue of the human GLUTX gene, such as a mouse GLUTX gene, can be isolated based on hybridization to the human GLUTX cDNA (described further above) and used as a transgene Intronic sequences and polyadenylation signals can also be included in the transgene to increase the efficiency of expression of the transgene A tissue-specific regulatory sequence(s) can be operably linked to the GLUTX transgene to direct expression of GLUTX protein to particular cells Methods for generating transgenic animals via embryo manipulation and microinjection, particularly animals such as mice, have become conventional in the art and are described, for example, in U S Pat Nos 4,736,866, 4,870,009, and 4,873,191 , and Hogan 1986, In MANIPULATING THE MOUSE EMBRYO, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N Y Similar methods are used for production of other transgenic animals A transgenic founder animal can be identified based upon the presence of the GLUTX transgene in its genome and/or expression of GLUTX mRNA in tissues or cells of the animals A transgenic founder animal can then be used to breed additional animals carrying the transgene Moreover, transgenic animals carrying a transgene encoding GLUTX can further be bred to other transgenic animals carrying other transgenes

To create a homologous recombinant animal, a vector is prepared which contains at least a portion of a GLUTX gene into which a deletion, addition or substitution has been introduced to thereby alter, e g , functionally disrupt, the GLUTX gene The GLUTX gene can be a human gene (e g , SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13), but more preferably, is a non-human homologue of a human GLUTX gene For example, a mouse homologue of human GLUTX gene of SEQ ID NO 1, 3, 5, 7, 9, 11 or 13 can be used to construct a homologous recombination vector suitable for altering an endogenous GLUTX gene in the mouse genome In one embodiment, the vector is designed such that, upon homologous recombination, the endogenous GLUTX gene is functionally disrupted (i e , no longer encodes a functional protein, also referred to as a "knock out" vector) Alternatively, the vector can be designed such that, upon homologous recombination, the endogenous GLUTX gene is mutated or otherwise altered but still encodes functional protein (e.g., the upstream regulatory region can be altered to thereby alter the expression of the endogenous GLUTX protein). In the homologous recombination vector, the altered portion of the GLUTX gene is flanked at its 5' and 3' ends by additional nucleic acid of the GLUTX gene to allow for homologous recombination to occur between the exogenous GLUTX gene carried by the vector and an endogenous GLUTX gene in an embryonic stem cell. The additional flanking GLUTX nucleic acid is of sufficient length for successful homologous recombination with the endogenous gene. Typically, several kilobases of flanking DNA (both at the 5' and 3' ends) are included in the vector. See e.g., Thomas et al. (1987) Cell 51 :503 for a description of homologous recombination vectors. The vector is introduced into an embryonic stem cell line (e.g., by electroporation) and cells in which the introduced GLUTX gene has homologously recombined with the endogenous GLUTX gene are selected (see e.g., Li et al. (1992) Cell 69:915). The selected cells are then injected into a blastocyst of an animal (e.g., a mouse) to form aggregation chimeras. See e.g., Bradley 1987, In: TERATOCARCINOMAS AND EMBRYONIC STEM CELLS: A PRACTICAL APPROACH, Robertson, ed. IRL, Oxford, pp. 1 13-152. A chimeric embryo can then be implanted into a suitable pseudopregnant female foster animal and the embryo brought to tenn. Progeny harboring the homologously recombined DNA in their germ cells can be used to breed animals in which all cells of the animal contain the homologously recombined DNA by germline transmission of the transgene. Methods for constructing homologous recombination vectors and homologous recombinant animals are described further in Bradley (1991) Curr Opin Bwtechnol 2:823-829; PCT International Publication Nos.: WO 90/1 1354; WO 91/01 140; WO 92/0968; and WO 93/04169. In another embodiment, transgenic non-humans animals can be produced that contain selected systems that allow for regulated expression of the transgene. One example of such a system is the cre/loxP recombinase system of bacteriophage PL For a description of the cre/loxP recombinase system, see, e.g., Lakso et al. (1992) PNAS 89:6232-6236. Another example of a recombinase system is the FLP recombinase system of Saccharomyces cerevisiae (O'Gorman et al. (1991) Science 251 :1351-1355. If a cre/loxP recombinase system is used to regulate expression of the transgene, animals containing transgenes encoding both the Cre recombinase and a selected protein are required. Such animals can be provided through the construction of "double" transgenic animals, e.g., by mating two transgenic animals, one containing a transgene encoding a selected protein and the other containing a transgene encoding a recombinase.

Clones of the non-human transgenic animals described herein can also be produced according to the methods described in Wilmut et al. (1997) Nature 385:810-813. In brief, a cell, e.g., a somatic cell, from the transgenic animal can be isolated and induced to exit the growth cycle and enter Go phase. The quiescent cell can then be fused, e.g., through the use of electrical pulses, to an enucleated oocyte from an animal of the same species from which the quiescent cell is isolated. The reconstructed oocyte is then cultured such that it develops to morula or blastocyte and then transferred to pseudopregnant female foster animal. The offspring borne of this female foster animal will be a clone of the animal from which the cell, e.g., the somatic cell, is isolated.

Pharmaceutical Compositions

The GLUTX nucleic acid molecules, GLUTX proteins, and anti-GLUTX antibodies (also referred to herein as "active compounds") of the invention, and derivatives, fragments, analogs and homologs thereof, can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the nucleic acid molecule, protein, or antibody and a pharmaceutically acceptable carrier. As used herein, "pharmaceutically acceptable carrier" is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with phaπnaceutical administration. Suitable carriers are described in the most recent edition of Remington's Pharmaceutical Sciences, a standard reference text in the field, which is incorporated herein by reference. Preferred examples of such carriers or diluents include, but are not limited to, water, saline, finger's solutions, dextrose solution, and 5% human serum albumin. Liposomes and non-aqueous vehicles such as fixed oils may also be used. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the compositions is contemplated. Supplementary active compounds can also be incorporated into the compositions.

A pharmaceutical composition of the invention is formulated to be compatible with its intended route of administration. Examples of routes of administration include parenteral, e.g., intravenous, intradermal, subcutaneous, oral (e.g., inhalation), transdermal (topical), transmucosal, and rectal administration. Solutions or suspensions used for parenteral, intradermal, or subcutaneous application can include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents, antibacterial agents such as benzyl alcohol or methyl parabens, antioxidants such as ascorbic acid or sodium bisulfite, chelating agents such as ethylenediammetetraacetic acid, buffers such as acetates, citrates or phosphates, and agents for the adjustment of tonicity such as sodium chloπde or dextrose The pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic

Pharmaceutical compositions suitable for mjectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile mjectable solutions or dispersion For intravenous administration, suitable carriers include physiological saline, bacteπo static water, Cremophor EL™ (BASF, Parsippany, N J ) or phosphate buffered saline (PBS) In all cases, the composition must be stenle and should be fluid to the extent that easy syπngeabihty exists It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi The earner can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), and suitable mixtures thereof The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as manitol, sorbitol, sodium chloride in the composition Prolonged absorption of the mjectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate and gelatin

Sterile mjectable solutions can be prepared by incorporating the active compound (e g , a GLUTX protein or anti-GLUTX antibody) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those enumerated above In the case of sterile powders for the preparation of sterile mjectable solutions, methods of preparation are vacuum drying and freeze-drymg that yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, troches, or capsules. Oral compositions can also be prepared using a fluid carrier for use as a mouthwash, wherein the compound in the fluid carrier is applied orally and swished and expectorated or swallowed. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystallme cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring.

For administration by inhalation, the compounds are delivered in the form of an aerosol spray from pressured container or dispenser which contains a suitable propellant, e.g., a gas such as carbon dioxide, or a nebulizer.

Systemic administration can also be by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, for transmucosal administration, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration can be accomplished through the use of nasal sprays or suppositories. For transdermal administration, the active compounds are formulated into ointments, salves, gels, or creams as generally known in the art.

The compounds can also be prepared in the form of suppositories (e.g., with conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery.

In one embodiment, the active compounds are prepared with earners that will protect the compound against rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from Alza Corporation and Nova Pharmaceuticals, Inc. Liposomal suspensions (including hposomes targeted to infected cells with monoclonal antibodies to viral antigens) can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art, for example, as described in U.S. Pat. No. 4,522,81 1.

It is especially advantageous to formulate oral or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subject to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. The specification for the dosage unit forms of the invention are dictated by and directly dependent on the unique characteristics of the active compound and the particular therapeutic effect to be achieved.

The nucleic acid molecules of the invention can be inserted into vectors and used as gene therapy vectors. Gene therapy vectors can be delivered to a subject by any of a number of routes, e.g., as described in U.S. Patent Nos. 5,703,055. Delivery can thus also include, e.g., intravenous injection, local administration (see U.S. Pat. No. 5,328,470) or stereotactic injection (see e.g., Chen et al. (1994) PNAS 91 :3054-3057). The pharmaceutical preparation of the gene therapy vector can include the gene therapy vector in an acceptable diluent, or can comprise a slow release matrix in which the gene delivery vehicle is imbedded. Alternatively, where the complete gene delivery vector can be produced intact from recombinant cells, e.g., retroviral vectors, the pharmaceutical preparation can include one or more cells that produce the gene delivery system.

The pharmaceutical compositions can be included in a container, pack, or dispenser together with instructions for administration.

Uses and Methods of the Invention

The nucleic acid molecules, proteins, protein homologues, and antibodies described herein can be used in one or more of the following methods: (a) screening assays; (b) detection assays (e.g., chromosomal mapping, tissue typing, forensic biology), (c) predictive medicine (e.g., diagnostic assays, prognostic assays, monitoring clinical trials, and pharmacogenomics); and (d) methods of treatment (e.g., therapeutic and prophylactic). As described herein, in one embodiment, a GLUTX protein of the invention has the ability to bind ATP. The isolated nucleic acid molecules of the invention can be used to express GLUTX protein (e.g. , via a recombinant expression vector in a host cell in gene therapy applications), to detect GLUTX mRNA (e.g., in a biological sample) or a genetic lesion in a GLUTX gene, and to modulate GLUTX activity, as described further below. In addition, the GLUTX proteins can be used to screen drugs or compounds that modulate the GLUTX activity or expression as well as to treat disorders characterized by insufficient or excessive production of GLUTX protein, for example proliferative or differentiative disorders, or production of GLUTX protein forms that have decreased or aberrant activity compared to GLUTX wild type protein. In addition, the anti-GLUTX antibodies of the invention can be used to detect and isolate GLUTX proteins and modulate GLUTX activity.

This invention further pertains to novel agents identified by the above described screening assays and uses thereof for treatments as described herein.

Screening Assays

The invention provides a method (also referred to herein as a "screening assay") for identifying modulators, i.e., candidate or test compounds or agents (e.g., peptides, peptidomimetics, small molecules or other drugs) that bind to GLUTX proteins or have a stimulatory or inhibitory effect on, for example, GLUTX expression or GLUTX activity. In one embodiment, the invention provides assays for screening candidate or test compounds which bind to or modulate the activity of a GLUTX protein or polypeptide or biologically active portion thereof. The test compounds of the present invention can be obtained using any of the numerous approaches in combinatorial library methods known in the art, including: biological libraries; spatially addressable parallel solid phase or solution phase libraries; synthetic library methods requiring deconvolution; the "one-bead one-compound" library method; and synthetic library methods using affinity chromatography selection. The biological library approach is limited to peptide libraries, while the other four approaches are applicable to peptide, non-peptide oligomer or small molecule libraries of compounds (Lam (1997) Anticancer Drug Des 12:145).

Examples of methods for the synthesis of molecular libraries can be found in the art, for example in: DeWitt et al (1993) Proc Natl Acad Sci U.S.A. 90:6909; Erb et al. (1994) Proc Natl Acad Sci U.S.A. 91 :1 1422; Zuckermann et al. (1994) J Med Chem 37:2678; Cho et al. (1993) Science 261 :1303; Carrell et al (1994) Angew Chem Int Ed Engl 33:2059; Carell et al. (1994) Angew Chem Int Ed Engl 33:2061; and Gallop et al. (1994) J Med Chem 37:1233.

Libraries of compounds may be presented in solution (e.g., Houghten (1992) Biotechniques 13:412-421), or on beads (Lam (1991) Nature 354:82-84), on chips (Fodor (1993) Nature 364 555-556), bacteria (Ladner U S Pat No 5,223,409), spores (Ladner USP

'409), plasmids (Cull et al (1992) Pi oc Natl Acad Sci USA 89 1865-1869) or on phage (Scott and Smith (1990) Science 249 386-390, Devlin (1990) Science 249 404-406, Cwirla et al (1990) Proc Natl Acad Sci USA 87 6378-6382, Fehci (1991) J Mol Biol 222 301-310, Ladner above )

In one embodiment, an assay is a cell-based assay in which a cell which expresses a membrane-bound form of GLUTX protein, oi a biologically active portion thereof, on the cell surface is contacted with a test compound and the ability of the test compound to bind to a GLUTX protein determined The cell, for example, can of mammalian origin or a yeast cell Detennining the ability of the test compound to bind to the GLUTX protein can be accomplished, for example, by coupling the test compound with a radioisotope or enzymatic label such that binding of the test compound to the GLUTX protein or biologically active portion thereof can be determined by detecting the labeled compound in a complex For example, test compounds can be labeled with ¹² , ^3SS, ¹⁴C, or ³H, either directly or indirectly, and the radioisotope detected by direct counting of radioemission or by scintillation counting Alternatively, test compounds can be enzymatically labeled with, for example, horseradish peroxidase, alkaline phosphatase, or luciferase, and the enzymatic label detected by determination of conversion of an appropriate substrate to product In one embodiment, the assay comprises contacting a cell which expresses a membrane-bound form of GLUTX protein, or a biologically active portion thereof, on the cell surface with a known compound which binds GLUTX to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with a GLUTX protein, wherein determining the ability of the test compound to interact with a GLUTX protein comprises detennining the ability of the test compound to preferentially bind to GLUTX or a biologically active portion thereof as compared to the known compound

In another embodiment, an assay is a cell-based assay comprising contacting a cell expressing a membrane-bound form of GLUTX protein, or a biologically active portion thereof, on the cell surface with a test compound and determining the ability of the test compound to modulate (e g , stimulate or inhibit) the activity of the GLUTX protein or biologically active portion thereof Determining the ability of the test compound to modulate the activity of GLUTX or a biologically active portion thereof can be accomplished, for example, by determining the ability of the GLUTX protein to bind to or interact with a GLUTX target molecule As used herein, a "target molecule" is a molecule with which a GLUTX protein binds or interacts in nature, for example, a molecule on the surface of a cell which expresses a GLUTX interacting protein, a molecule on the surface of a second cell, a molecule in the extracellular milieu, a molecule associated with the internal surface of a cell membrane or a cytoplasmic molecule A GLUTX target molecule can be a non-GLUTX molecule or a GLUTX protein or polypeptide of the present invention In one embodiment, a GLUTX target molecule is a component of a signal transduction pathway that facilitates transduction of an extracellular signal (e g , a signal generated by binding of a compound to a membrane-bound GLUTX molecule) through the cell membrane and into the cell The target, for example, can be a second intercellular protein that has catalytic activity or a protein that facilitates the association of downstream signaling molecules with GLUTX Determining the ability of the GLUTX protein to bind to or interact with a GLUTX target molecule can be accomplished by one of the methods described above for determining direct binding In one embodiment, determining the ability of the GLUTX protein to bind to or interact with a GLUTX target molecule can be accomplished by determining the activity of the target molecule For example, the activity of the target molecule can be determined by detecting induction of a cellular second messenger of the target (i e mtracellular Ca , diacylglycerol, IP₃, etc ), detecting catalytic/enzymatic activity of the target an appropriate substrate, detecting the induction of a reporter gene (comprising a GLUTX-responsive regulatory element operatively linked to a nucleic acid encoding a detectable marker, e g , luciferase), or detecting a cellular response, for example, cell survival, cellular differentiation, or cell proliferation

In yet another embodiment, an assay of the present invention is a cell-free assay compπsing contacting a GLUTX protein or biologically active portion thereof with a test compound and determining the ability of the test compound to bind to the GLUTX protein or biologically active portion thereof Binding of the test compound to the GLUTX protein can be determined either directly or indirectly as described above In one embodiment, the assay comprises contacting the GLUTX protein or biologically active portion thereof with a known compound which binds GLUTX to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with a GLUTX protein, wherein determining the ability of the test compound to interact with a GLUTX protein comprises determining the ability of the test compound to preferentially bind to GLUTX or biologically active portion thereof as compared to the known compound

In another embodiment, an assay is a cell-free assay comprising contacting GLUTX protein or biologically active portion thereof with a test compound and determining the ability of the test compound to modulate (e g , stimulate or inhibit) the activity of the GLUTX protein or biologically active portion thereof. Determining the ability of the test compound to modulate the activity of GLUTX can be accomplished, for example, by determining the ability of the GLUTX protein to bind to a GLUTX target molecule by one of the methods described above for determining direct binding. In an alternative embodiment, determining the ability of the test compound to modulate the activity of GLUTX can be accomplished by determining the ability of the GLUTX protein further modulate a GLUTX target molecule. For example, the catalytic/enzymatic activity of the target molecule on an appropriate substrate can be determined as previously described.

In yet another embodiment, the cell-free assay comprises contacting the GLUTX protein or biologically active portion thereof with a known compound which binds GLUTX to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with a GLUTX protein, wherein determining the ability of the test compound to interact with a GLUTX protein comprises determining the ability of the GLUTX protein to preferentially bind to or modulate the activity of a GLUTX target molecule.

The cell-free assays of the present invention are amenable to use of both the soluble form or the membrane-bound form of GLUTX. In the case of cell-free assays comprising the membrane-bound form of GLUTX, it may be desirable to utilize a solubilizing agent such that the membrane-bound form of GLUTX is maintained in solution. Examples of such solubilizing agents include non-ionic detergents such as n-octylglucoside, n-dodecylglucoside, n-dodecylmaltoside, octanoyl-N-mefhylglucamide, decanoyl-N-methylglucamide, Triton^® X-100, Triton⁰¹ X-l 14, Thesit*, Isotridecypoly(ethylene glycol ether)_n, N-dodecyl— N,N-dimethyl-3-ammonio- 1 -propane sulfonate, 3-(3-cholamidopropyl)dimethylamminiol- 1 -propane sulfonate (CHAPS), or 3-(3-cholamidopropyl)dimethylamminiol-2-hydroxy- 1 -propane sulfonate (CHAPSO).

In more than one embodiment of the above assay methods of the present invention, it may be desirable to immobilize either GLUTX or its target molecule to facilitate separation of complexed from uncomplexed forms of one or both of the proteins, as well as to accommodate automation of the assay. Binding of a test compound to GLUTX, or interaction of GLUTX with a target molecule in the presence and absence of a candidate compound, can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtiter plates, test tubes, and micro-centrifuge tubes. In one embodiment, a fusion protein can be provided that adds a domain that allows one or both of the proteins to be bound to a matrix. For example, GST-GLUTX fusion proteins or GST-target fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical, St Louis, MO) or glutathione deπvatized microtiter plates, that are then combined with the test compound or the test compound and either the non-adsorbed target protein or GLUTX protein, and the mixture is incubated under conditions conducive to complex formation (e g , at physiological conditions for salt and pH) Following incubation, the beads or microtiter plate wells are washed to remove any unbound components, the matrix immobilized in the case of beads, complex determined either directly or indirectly, for example, as described above Alternatively, the complexes can be dissociated from the matrix, and the level of GLUTX binding or activity determined using standard techniques Other techniques for immobilizing proteins on matrices can also be used in the screening assays of the invention For example, either GLUTX or its target molecule can be immobilized utilizing conjugation of biotin and streptavidin Biotinylated GLUTX or target molecules can be prepared from biotin-NHS (N-hydroxy-succimmide) using techniques well known in the art (e g , biotinylation kit, Pierce Chemicals, Rockford, 111 ), and immobilized in the wells of streptavidin-coated 96 well plates (Pierce Chemical) Alternatively, antibodies reactive with GLUTX or target molecules, but which do not interfere with binding of the GLUTX protein to its target molecule, can be deπvatized to the wells of the plate, and unbound target or GLUTX trapped in the wells by antibody conjugation Methods for detecting such complexes, in addition to those descπbed above for the GST-immobihzed complexes, include immunodetection of complexes using antibodies reactive with the GLUTX or target molecule, as well as enzyme-linked assays that rely on detecting an enzymatic activity associated with the GLUTX or target molecule

In another embodiment, modulators of GLUTX expression are identified in a method wherein a cell is contacted with a candidate compound and the expression of GLUTX mRNA or protein in the cell is determined The level of expression of GLUTX mRNA or protein in the presence of the candidate compound is compared to the level of expression of GLUTX mRNA or protein in the absence of the candidate compound The candidate compound can then be identified as a modulator of GLUTX expression based on this companson For example, when expression of GLUTX mRNA or protein is greater (statistically significantly greater) in the presence of the candidate compound than m its absence, the candidate compound is identified as a stimulator of GLUTX mRNA or protein expression Alternatively, when expression of GLUTX mRNA or protein is less (statistically significantly less) in the presence of the candidate compound than in its absence, the candidate compound is identified as an inhibitor of GLUTX mRNA or protein expression The level of GLUTX mRNA or protein expression in the cells can be determined by methods described herein for detecting GLUTX mRNA or protein.

In yet another aspect of the invention, the GLUTX proteins can be used as "bait proteins" in a two-hybrid assay or three hybrid assay (see, e.g., U.S. Pat. No. 5,283,317; Zervos et al (1993) Cell 72:223-232; Madura et al (1993) J Biol Chem 268: 12046-12054; Bartel et al. (1993) Biotechniques 14:920-924; Iwabuchi et al. (1993) Oncogene 8: 1693-1696; and Brent WO94/10300), to identify other proteins that bind to or interact with GLUTX ("GLUTX-binding proteins" or "GLUTX-bp") and modulate GLUTX activity. Such GLUTX-binding proteins are also likely to be involved in the propagation of signals by the GLUTX proteins as, for example, upstream or downstream elements of the GLUTX pathway. The two-hybrid system is based on the modular nature of most transcription factors, which consist of separable DNA-binding and activation domains. Briefly, the assay utilizes two different DNA constructs. In one construct, the gene that codes for GLUTX is fused to a gene encoding the DNA binding domain of a known transcription factor (e.g., GAL-4). In the other construct, a DNA sequence, from a library of DNA sequences, that encodes an unidentified protein ("prey" or "sample") is fused to a gene that codes for the activation domain of the known transcription factor. If the "bait" and the "prey" proteins are able to interact, in vivo, forming a GLUTX-dependent complex, the DNA-binding and activation domains of the transcription factor are brought into close proximity. This proximity allows transcription of a reporter gene (e.g., LacZ) that is operably linked to a transcriptional regulatory site responsive to the transcription factor. Expression of the reporter gene can be detected and cell colonies containing the functional transcription factor can be isolated and used to obtain the cloned gene that encodes the protein which interacts with GLUTX.

This invention further pertains to novel agents identified by the above-described screening assays and uses thereof for treatments as described herein.

Detection Assays

Portions or fragments of the cDNA sequences identified herein (and the corresponding complete gene sequences) can be used in numerous ways as polynucleotide reagents. For example, these sequences can be used to: (i) map their respective genes on a chromosome; and, thus, locate gene regions associated with genetic disease; (ii) identify an individual from a minute biological sample (tissue typing); and (iii) aid in forensic identification of a biological sample.

The GLUTX sequences of the present invention can also be used to identify individuals from minute biological samples. In this technique, an individual's genomic DNA is digested with one or more restriction enzymes, and probed on a Southern blot to yield unique bands for identification. The sequences of the present invention are useful as additional DNA markers for RFLP ("restriction fragment length polymoφhisms," described in U.S. Pat. No. 5,272,057). Furthermore, the sequences of the present invention can be used to provide an alternative technique that determines the actual base-by-base DNA sequence of selected portions of an individual's genome. Thus, the GLUTX sequences described herein can be used to prepare two PCR primers from the 5' and 3' ends of the sequences. These primers can then be used to amplify an individual's DNA and subsequently sequence it. Panels of conesponding DNA sequences from individuals, prepared in this manner, can provide unique individual identifications, as each individual will have a unique set of such DNA sequences due to allelic differences. The sequences of the present invention can be used to obtain such identification sequences from individuals and from tissue. The GLUTX sequences of the invention uniquely represent portions of the human genome. Allelic variation occurs to some degree in the coding regions of these sequences, and to a greater degree in the noncoding regions. It is estimated that allelic variation between individual humans occurs with a frequency of about once per each 500 bases. Much of the allelic variation is due to single nucleotide polymoφhisms (SNPs), which include restriction fragment length polymoφhisms (RFLPs). Each of the sequences described herein can, to some degree, be used as a standard against which DNA from an individual can be compared for identification puφoses. Because greater numbers of polymoφhisms occur in the noncoding regions, fewer sequences are necessary to differentiate individuals. The noncoding sequences of SEQ ID NOT , 3, 5, 7, 9, 11 or 13, as described above, can comfortably provide positive individual identification with a panel of perhaps 10 to 1 ,000 primers that each yield a noncoding amplified sequence of 100 bases. If predicted coding sequences are used, a more appropriate number of primers for positive individual identification would be 500-2,000.

Predictive Medicine

The present invention also pertains to the field of predictive medicine in which diagnostic assays, prognostic assays, pharmacogenomics, and monitoring clinical trials are used for prognostic (predictive) puφoses to thereby treat an individual prophylactically. Accordingly, one aspect of the present invention relates to diagnostic assays for determining GLUTX protein and/or nucleic acid expression as well as GLUTX activity, in the context of a biological sample (e.g., blood, serum, cells, tissue) to thereby determine whether an individual is afflicted with a disease or disorder, or is at risk of developing a disorder, associated with aberrant GLUTX expression or activity. The invention also provides for prognostic (or predictive) assays for determining whether an individual is at risk of developing a disorder associated with GLUTX protein, nucleic acid expression or activity. For example, mutations in a GLUTX gene can be assayed in a biological sample. Such assays can be used for prognostic or predictive puφose to thereby prophylactically treat an individual prior to the onset of a disorder characterized by or associated with GLUTX protein, nucleic acid expression or activity.

Another aspect of the invention provides methods for determining GLUTX protein, nucleic acid expression or GLUTX activity in an individual to thereby select appropriate therapeutic or prophylactic agents for that individual (referred to herein as "pharmacogenomics"). Pharmacogenomics allows for the selection of agents (e.g., drugs) for therapeutic or prophylactic treatment of an individual based on the genotype of the individual (e.g., the genotype of the individual examined to determine the ability of the individual to respond to a particular agent.)

Yet another aspect of the invention pertains to monitoring the influence of agents (e.g., drugs, compounds) on the expression or activity of GLUTX in clinical trials.

These and other agents are described in further detail in the following sections.

Diagnostic Assays Many, if not all, homologous proteins are known in the art to have closely related or identical functions. See, e.g., Lewin, "Chapter 21 : Structural Genes Belong to Families" In: GENES II, 1985, John Wiley and Sons, Inc., New York. The GLUTX polypeptide have homology to the GLUTl -5 and GLUT8 proteins, which was shown previously to be specifically involved in facultative transport of hexose (see above). Therefore, it is presumed that GLUTX would also modulate transport of hexose. GLUTX may thus be particularly useful in diagnosing disorders related to aberrant hexose regulation and the like. Oligonucleotides corresponding to any one portion of the GLUTX nucleic acids of SEQ ID NO: l, 3, 5, 7, 9, 1 1 or 13 may be used to detect the expression of a GLUTX-like gene. The proteins of the invention may be used to stimulate production of antibodies specifically binding the proteins. Such antibodies may be used in immunodiagnostic procedures to detect the occurrence of the protein in a sample.

An exemplary method for detecting the presence or absence of GLUTX in a biological sample involves obtaining a biological sample from a test subject and contacting the biological sample with a compound or an agent capable of detecting GLUTX protein or nucleic acid

(e.g., mRNA, genomic DNA) that encodes GLUTX protein such that the presence of GLUTX is detected in the biological sample. An agent for detecting GLUTX mRNA or genomic DNA is a labeled nucleic acid probe capable of hybridizing to GLUTX mRNA or genomic DNA. The nucleic acid probe can be, for example, a full-length GLUTX nucleic acid, such as the nucleic acid of SEQ ID NOT, 3, 5, 7, 9, 11 or 13, or a portion thereof, such as an oligonucleotide of at least 15, 30, 50, 100, 250 or 500 nucleotides in length and sufficient to specifically hybridize under stringent conditions to GLUTX mRNA or genomic DNA, as described above. Other suitable probes for use in the diagnostic assays of the invention are described herein.

An agent for detecting GLUTX protein is an antibody capable of binding to GLUTX protein, preferably an antibody with a detectable label. Antibodies can be polyclonal, or more preferably, monoclonal. An intact antibody, or a fragment thereof (e.g., Fab or F(ab')₂) can be used. The tenn "labeled", with regard to the probe or antibody, is intended to encompass direct labeling of the probe or antibody by coupling (i.e., physically linking) a detectable substance to the probe or antibody, as well as indirect labeling of the probe or antibody by reactivity with another reagent that is directly labeled. Examples of indirect labeling include detection of a primary antibody using a fluorescently labeled secondary antibody and end-labeling of a DNA probe with biotin such that it can be detected with fluorescently labeled streptavidin. The term "biological sample" is intended to include tissues, cells and biological fluids isolated from a subject, as well as tissues, cells and fluids present within a subject. That is, the detection method of the invention can be used to detect GLUTX mRNA, protein, or genomic DNA in a biological sample in vitro as well as in vivo. For example, in vitro techniques for detection of GLUTX mRNA include Northern hybridizations and in situ hybridizations. In vitro techniques for detection of GLUTX protein include enzyme linked immunosorbent assays (ELISAs), Western blots, immunoprecipitations and immunofluorescence. In vitro techniques for detection of GLUTX genomic DNA include Southern hybridizations. Furthermore, in vivo techniques for detection of GLUTX protein include introducing into a subject a labeled anti-GLUTX antibody. For example, the antibody can be labeled with a radioactive marker whose presence and location in a subject can be detected by standard imaging techniques.

In one embodiment, the biological sample contains protein molecules from the test subject. Alternatively, the biological sample can contain mRNA molecules from the test subject or genomic DNA molecules from the test subject A preferred biological sample is a peripheral blood leukocyte sample isolated by conventional means from a subject

In another embodiment, the methods further involve obtaining a control biological sample from a control subject, contacting the control sample with a compound or agent capable of detecting GLUTX protein, mRNA, or genomic DNA, such that the presence of

GLUTX protein, mRNA or genomic DNA is detected in the biological sample, and comparing the presence of GLUTX protein, mRNA or genomic DNA in the control sample with the presence of GLUTX protein. mRNA or genomic DNA in the test sample

The invention also encompasses kits for detecting the presence of GLUTX in a biological sample For example, the kit can comprise a labeled compound or agent capable of detecting GLUTX protein or mRNA in a biological sample, means for determining the amount of GLUTX in the sample, and means for comparing the amount of GLUTX in the sample with a standard The compound or agent can be packaged in a suitable container The kit can further comprise instructions for using the kit to detect GLUTX protein or nucleic acid Prognostic Assays

The diagnostic methods described herein can furthermore be utilized to identify subjects having or at risk of developing a disease or disorder associated with aberrant GLUTX expression or activity For example, the assays described herein, such as the preceding diagnostic assays or the following assays, can be utilized to identify a subject having or at risk of developing a disorder associated with GLUTX protein, nucleic acid expression or activity in, e g abenant hexose transport disordeis, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc Alternatively, the prognostic assays can be utilized to identify a subject having or at risk for developing a disease or disorder Thus, the present invention provides a method for identifying a disease or disorder associated with abenant GLUTX expression or activity in which a test sample is obtained from a subject and GLUTX protein or nucleic acid (e g , mRNA, genomic DNA) is detected, wherein the presence of GLUTX protein or nucleic acid is diagnostic for a subject having or at risk of developing a disease or disorder associated with aberrant GLUTX expression or activity As used herein, a "test sample" refers to a biological sample obtained from a subject of interest For example, a test sample can be a biological fluid (e g , serum), cell sample, or tissue

Furthermore, the prognostic assays described herein can be used to determine whether a subject can be administered an agent (e g , an agonist, antagonist, peptidomimetic, protein, peptide, nucleic acid, small molecule, or other drug candidate) to treat a disease or disorder associated with aberrant GLUTX expression or activity For example, such methods can be used to determine whether a subject can be effectively treated with an agent for a disorder, such as a aberrant hexose transport disorders, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc. Thus, the present invention provides methods for determining whether a subject can be effectively treated with an agent for a disorder associated with aberrant GLUTX expression or activity in which a test sample is obtained and GLUTX protein or nucleic acid is detected (e.g., wherein the presence of GLUTX protein or nucleic acid is diagnostic for a subject that can be administered the agent to treat a disorder associated with abenant GLUTX expression or activity.)

The methods of the invention can also be used to detect genetic lesions in a GLUTX gene, thereby determining if a subject with the lesioned gene is at risk for, or suffers from, a abenant hexose transport disorders, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc. In various embodiments, the methods include detecting, in a sample of cells from the subject, the presence or absence of a genetic lesion characterized by at least one of an alteration affecting the integrity of a gene encoding a GLUTX-protein, or the mis-expression of the GLUTX gene. For example, such genetic lesions can be detected by ascertaining the existence of at least one of (1) a deletion of one or more nucleotides from a GLUTX gene; (2) an addition of one or more nucleotides to a GLUTX gene; (3) a substitution of one or more nucleotides of a GLUTX gene, (4) a chromosomal rearrangement of a GLUTX gene; (5) an alteration in the level of a messenger RNA transcript of a GLUTX gene, (6) abenant modification of a GLUTX gene, such as of the methylation pattern of the genomic

DNA, (7) the presence of a non-wild type splicing pattern of a messenger RNA transcript of a GLUTX gene, (8) a non-wild type level of a GLUTX-protein, (9) allelic loss of a GLUTX gene, and (10) inappropriate post-translational modification of a GLUTX-protein. As described herein, there are a large number of assay techniques known in the art which can be used for detecting lesions in a GLUTX gene. A prefened biological sample is a peripheral blood leukocyte sample isolated by conventional means from a subject. However, any biological sample containing nucleated cells may be used, including, for example, buccal mucosal cells.

In certain embodiments, detection of the lesion involves the use of a probe/primer in a polymerase chain reaction (PCR) (see, e.g., U.S. Pat. Nos. 4,683,195 and 4,683,202), such as anchor PCR or "rapid amplification of cDNA ends" (RACE PCR), or, alternatively, in a ligation chain reaction (LCR) (see, e.g., Landegran et al. (1988) Science 241 :1077-1080; and Nakazawa et al (1994) PNAS 91 :360-364), the latter of which can be particularly useful for detecting point mutations in the GLUTX-gene (see Abravaya et al. (1995) Nucl Acids Res 23 675-682) This method can include the steps of collecting a sample of cells from a patient, isolating nucleic acid (e g , genomic, mRNA or both) from the cells of the sample, contacting the nucleic acid sample with one or more primers that specifically hybridize to a GLUTX gene under conditions such that hybridization and amplification of the GLUTX gene (if present) occurs, and detecting the presence or absence of an amplification product, or detecting the size of the amplification product and comparing the length to a control sample It is anticipated that PCR and/or LCR may be desirable to use as a preliminary amplification step in conjunction with any of the techniques used for detecting mutations described herein Alternative amplification methods include self sustained sequence replication (Guatelh et al , 1990, Proc Natl Acad Sci USA 87 1874-1878), transcriptional amplification system (Kwoh, et al , 1989, Proc Natl Acad Sci USA 86 1173-1177), Q-Beta Rephcase (Lizardi et al, 1988, BwTechnologv 6 1 197), or any other nucleic acid amplification method, followed by the detection of the amplified molecules using techniques well known to those of skill in the art These detection schemes aie especially useful for the detection of nucleic acid molecules if such molecules are present in very low numbers

In an alternative embodiment, mutations in a GLUTX gene from a sample cell can be identified by alterations in restriction enzyme cleavage patterns For example, sample and control DNA is isolated, amplified (optionally), digested with one or more restriction endonucleases, and fragment length sizes are determined by gel electrophoresis and compared Differences in fragment length sizes between sample and control DNA indicates mutations in the sample DNA Moreover, the use of sequence specific ribozymes (see, for example, U S Pat No 5,493,531) can be used to score for the presence of specific mutations by development or loss of a ribozyme cleavage site

In other embodiments, genetic mutations in GLUTX can be identified by hybridizing a sample and control nucleic acids, e g , DNA or RNA, to high density anays containing hundreds or thousands of oligonucleotides probes (Cronin et al (1996) Human Mutation 1 244-255, Kozal et al (1996) Nature Medicine 2 753-759) For example, genetic mutations in GLUTX can be identified in two dimensional arrays containing light-generated DNA probes as described in Cronin et al above Briefly, a first hybridization array of probes can be used to scan through long stretches of DNA in a sample and control to identify base changes between the sequences by making linear anays of sequential overlapping probes This step allows the identification of point mutations This step is followed by a second hybridization anay that allows the characterization of specific mutations by using smaller, specialized probe arrays complementary to all vanants or mutations detected Each mutation array is composed of parallel probe sets, one complementary to the wild-type gene and the other complementary to the mutant gene

In yet another embodiment, any of a vanety of sequencing reactions known in the art can be used to directly sequence the GLUTX gene and detect mutations by comparing the sequence of the sample GLUTX with the corresponding wild-type (control) sequence

Examples of sequencing reactions include those based on techniques developed by Maxim and Gilbert (1977) PNAS 74 560 or Sanger (1977) PNAS 74 5463 It is also contemplated that any of a variety of automated sequencing procedures can be utilized when performing the diagnostic assays (Naeve et al , (1995) Biotechniques 19 448), including sequencing by mass spectrometry (see, e g , PCT International Publ No WO 94/16101 , Cohen et al (1996) Adv Chromatogr 36 127-162, and Griffin et al (1993) Appl Biochem Bwtechnol 38 147-159)

Other methods for detecting mutations m the GLUTX gene include methods in which protection from cleavage agents is used to detect mismatched bases in RNA/RNA or RNA/DNA heteroduplexes (Myers et al (1985) Science 230 1242) In general, the art technique of "mismatch cleavage" starts by providing heteroduplexes of formed by hybridizing (labeled) RNA or DNA containing the wild-type GLUTX sequence with potentially mutant RNA or DNA obtained from a tissue sample The double-stranded duplexes are treated with an agent that cleaves smgle-stranded regions of the duplex such as which will exist due to basepair mismatches between the control and sample strands For instance, RNA/DNA duplexes can be treated with RNase and DNA/DNA hybrids treated with SI nuclease to enzymatically digesting the mismatched regions In other embodiments, either DNA/DNA or RNA/DNA duplexes can be treated with hydroxylamine or osmium tetroxide and with pipeπdine in order to digest mismatched regions After digestion of the mismatched regions, the resulting material is then separated by size on denaturing polyacrylamide gels to determine the site of mutation See, for example, Cotton et al (1988) Proc Natl Acad Sci USA 85 4397, Saleeba et al (1992) Methods Enzvmol 217 286-295 In an embodiment, the control DNA or RNA can be labeled for detection

In still another embodiment, the mismatch cleavage reaction employs one or more proteins that recognize mismatched base pairs in double-stranded DNA (so called "DNA mismatch repair" enzymes) in defined systems for detecting and mapping point mutations in GLUTX cDNAs obtained from samples of cells For example, the mutY enzyme of £ coli cleaves A at G/A mismatches and the thymidine DNA glycosylase from HeLa cells cleaves T at G/T mismatches (Hsu et al (1994) Carcinogenesis 15 1657-1662) According to an exemplary embodiment, a probe based on a GLUTX sequence, e g , a wild-type GLUTX sequence, is hybridized to a cDNA or other DNA product from a test cell(s). The duplex is treated with a DNA mismatch repair enzyme, and the cleavage products, if any, can be detected from electrophoresis protocols or the like. See, for example, U.S. Pat. No. 5,459,039. In other embodiments, alterations in electrophoretic mobility will be used to identify mutations in GLUTX genes. For example, single strand conformation polymoφhism (SSCP) may be used to detect differences in electrophoretic mobility between mutant and wild type nucleic acids (Orita et al. (1989) Proc Natl Acad Sci USA: 86:2766, see also Cotton (1993) Mutat Res 285: 125-144; Hayashi (1992) Genet Anal Tech Appl 9:73-79). Single-stranded DNA fragments of sample and control GLUTX nucleic acids will be denatured and allowed to renature. The secondary structure of single-stranded nucleic acids varies according to sequence, the resulting alteration in electrophoretic mobility enables the detection of even a single base change. The DNA fragments may be labeled or detected with labeled probes. The sensitivity of the assay may be enhanced by using RNA, rather than DNA, in which the secondary structure is more sensitive to a change in sequence. In one embodiment, the subject method utilizes heteroduplex analysis to separate double stranded heteroduplex molecules on the basis of changes in electrophoretic mobility. See, e.g., Keen et al. (1991) Trends Genet 7:5.

In yet another embodiment the movement of mutant or wild-type fragments in polyacrylamide gels containing a gradient of denaturant is assayed using denaturing gradient gel electrophoresis (DGGE). See, e.g., Myers et al (1985) Nature 313:495. When DGGE is used as the method of analysis, DNA will be modified to insure that it does not completely denature, for example by adding a GC clamp of approximately 40 bp of high-melting GC-rich DNA by PCR. In a further embodiment, a temperature gradient is used in place of a denaturing gradient to identify differences in the mobility of control and sample DNA. See, e.g., Rosenbaum and Reissner (1987) Biophys Chem 265:12753.

Examples of other techniques for detecting point mutations include, but are not limited to, selective oligonucleotide hybridization, selective amplification, or selective primer extension. For example, oligonucleotide primers may be prepared in which the known mutation is placed centrally and then hybridized to target DNA under conditions that permit hybridization only if a perfect match is found. See, e.g., Saiki et al. (1986) Nature 324:163); Saiki et al. (1989) Proc Natl Acad. Sci USA 86:6230. Such allele specific oligonucleotides are hybridized to PCR amplified target DNA or a number of different mutations when the oligonucleotides are attached to the hybridizing membrane and hybridized with labeled target DNA. Alternatively, allele specific amplification technology that depends on selective PCR amplification may be used in conjunction with the instant invention. Oligonucleotides used as primers for specific amplification may carry the mutation of interest in the center of the molecule (so that amplification depends on differential hybridization) (Gibbs et al. (1989) Nucleic Acids Res 17:2437-2448) or at the extreme 3' end of one primer where, under appropriate conditions, mismatch can prevent, or reduce polymerase extension (Prossner (1993) Tibtech 1 1 :238). In addition it may be desirable to introduce a novel restriction site in the region of the mutation to create cleavage-based detection. See, e.g., Gasparini et al (1992) Mol Cell Probes 6: 1. It is anticipated that in certain embodiments amplification may also be performed using Taq ligase for amplification. See, e.g., Barany (1991) Proc Natl Acad Sci

USA 88:189. In such cases, ligation will occur only if there is a perfect match at the 3' end of the 5' sequence, making it possible to detect the presence of a known mutation at a specific site by looking for the presence or absence of amplification.

The methods described herein may be performed, for example, by utilizing pre-packaged diagnostic kits comprising at least one probe nucleic acid or antibody reagent described herein, which may be conveniently used, e.g., in clinical settings to diagnose patients exhibiting symptoms or family history of a disease or illness involving a GLUTX gene.

Furthermore, any cell type or tissue, preferably peripheral blood leukocytes, in which GLUTX is expressed may be utilized in the prognostic assays described herein. However, any biological sample containing nucleated cells may be used, including, for example, buccal mucosal cells.

Pharmacogenomics

Agents, or modulators that have a stimulatory or inhibitory effect on GLUTX activity (e.g., GLUTX gene expression), as identified by a screening assay described herein can be administered to individuals to treat abenant hexose transport disorders, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc., associated with aberrant GLUTX activity. In conjunction with such treatment, the pharmacogenomics (i.e., the study of the relationship between an individual's genotype and that individual's response to a foreign compound or drug) of the individual may be considered. Differences in metabolism of therapeutics can lead to severe toxicity or therapeutic failure by altering the relation between dose and blood concentration of the pharmacologically active drug. Thus, the pharmacogenomics of the individual permits the selection of effective agents (e.g., drugs) for prophylactic or therapeutic treatments based on a consideration of the individual's genotype. Such pharmacogenomics can further be used to determine appropriate dosages and therapeutic regimens Accordingly, the activity of GLUTX protein, expression of GLUTX nucleic acid, or mutation content of GLUTX genes in an individual can be determined to thereby select appropriate agent(s) for therapeutic or prophylactic treatment of the individual Pharmacogenomics deals with clinically significant hereditary variations in the response to drugs due to altered diug disposition and abnormal action in affected persons See e g , Eichelbaum, 1996, Clin Exp Pharmacol Physiol, 23 983-985 and Linder, 1997, Chn Chem, 43 254-266 In general, two types of pharmacogenetic conditions can be differentiated Genetic conditions transmitted as a single factor altering the way drugs act on the body (altered drug action) or genetic conditions transmitted as single factors altering the way the body acts on drugs (altered drug metabolism) These pharmacogenetic conditions can occur either as rare defects or as polymoφhisms For example, glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common inherited enzymopathy in which the main clinical complication is haemolysis after ingestion of oxidant drugs (anti-malaπals, sulfonamides, analgesics, mtrofurans) and consumption of fava beans

As an illustrative embodiment, the activity of drug metabolizing enzymes is a major determinant of both the intensity and duration of drug action The discovery of genetic polymoφhisms of drug metabolizing enzymes (e g , N-acetyltransferase 2 (NAT 2) and cytochrome P450 enzymes CYP2D6 and CYP2C19) has provided an explanation as to why some patients do not obtain the expected drug effects or show exaggerated drug response and serious toxicity after taking the standard and safe dose of a drug These polymoφhisms are expressed in two phenotypes in the population, the extensive metabohzer (EM) and poor metabohzer (PM) The prevalence of PM is different among different populations For example, the gene coding for CYP2D6 is highly polymoφhic and several mutations have been identified in PM, which all lead to the absence of functional CYP2D6 Poor metabohzers of CYP2D6 and CYP2C19 quite frequently experience exaggerated drug response and side effects when they receive standard doses If a metabolite is the active therapeutic moiety, PM show no therapeutic response, as demonstrated for the analgesic effect of codeine mediated by its CYP2D6-formed metabolite moφhine The other extreme are the so called ultra-rapid metabohzers who do not respond to standard doses Recently, the molecular basis of ultra-rapid metabolism has been identified to be due to CYP2D6 gene amplification

Thus, the activity of GLUTX protein, expression of GLUTX nucleic acid, or mutation content of GLUTX genes in an individual can be determined to thereby select appropnate agent(s) for therapeutic or prophylactic treatment of the individual In addition, pharmacogenetic studies can be used to apply genotyping of polymoφhic alleles encoding drug-metabolizing enzymes to the identification of an individual's drug responsiveness phenotype. This knowledge, when applied to dosing or drug selection, can avoid adverse reactions or therapeutic failure and thus enhance therapeutic or prophylactic efficiency when treating a subject with a GLUTX modulator, such as a modulator identified by one of the exemplary screening assays described herein.

Monitoring Clinical Efficacy

Monitoring the influence of agents (e.g., drugs, compounds) on the expression or activity of GLUTX (e.g., the abenant hexose transport disorders, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc.) can be applied in basic drug screening and in clinical trials. For example, the effectiveness of an agent determined by a screening assay as described herein to increase GLUTX gene expression, protein levels, or upregulate GLUTX activity, can be monitored in clinical trials of subjects exhibiting decreased GLUTX gene expression, protein levels, or downregulated GLUTX activity. Alternatively, the effectiveness of an agent determined by a screening assay to decrease GLUTX gene expression, protein levels, or downregulate GLUTX activity, can be monitored in clinical trials of subjects exhibiting increased GLUTX gene expression, protein levels, or upregulated GLUTX activity. In such clinical trials, the expression or activity of GLUTX and, preferably, other genes that have been implicated in, for example, a proliferative or neurological disorder, can be used as a "read out" or marker of the responsiveness of a particular cell.

For example, genes, including GLUTX, that are modulated in cells by treatment with an agent (e.g., compound, drug or small molecule) that modulates GLUTX activity (e.g., identified in a screening assay as described herein) can be identified. Thus, to study the effect of agents on aberrant hexose transport disorders, including but not limited to ischemia, hyperglycemia, hypoglycemia, diabetes, etc., for example, in a clinical trial, cells can be isolated and RNA prepared and analyzed for the levels of expression of GLUTX and other genes implicated in the disorder. The levels of gene expression (i.e., a gene expression pattern) can be quantified by Northern blot analysis or RT-PCR, as described herein, or alternatively by measuring the amount of protein produced, by one of the methods as described herein, or by measuring the levels of activity of GLUTX or other genes. In this way, the gene expression pattern can serve as a marker, indicative of the physiological response of the cells to the agent. Accordingly, this response state may be determined before, and at various points during, treatment of the individual with the agent. In one embodiment, the invention provides a method for monitoring the effectiveness of treatment of a subject with an agent (e.g., an agonist, antagonist, protein, peptide, nucleic acid, peptidomimetic, small molecule, or other drug candidate identified by the screening assays described herein) comprising the steps of (/^') obtaining a pre-administration sample from a subject prior to administration of the agent; (ii) detecting the level of expression of a GLUTX protein, mRNA, or genomic DNA in the preadministration sample; (Hi) obtaining one or more post-administration samples from the subject; (iv) detecting the level of expression or activity of the GLUTX protein, mRNA, or genomic DNA in the post-administration samples; (v) comparing the level of expression or activity of the GLUTX protein, mRNA, or genomic DNA in the pre-administration sample with the GLUTX protein, mRNA, or genomic DNA in the post administration sample or samples; and (vi) altering the administration of the agent to the subject accordingly. For example, increased administration of the agent may be desirable to increase the expression or activity of GLUTX to higher levels than detected, i.e., to increase the effectiveness of the agent. Alternatively, decreased administration of the agent may be desirable to decrease expression or activity of GLUTX to lower levels than detected, i.e., to decrease the effectiveness of the agent.

Methods of Treatment

The present invention provides for both prophylactic and therapeutic methods of treating a subject at risk of (or susceptible to) a disorder or having a disorder associated with aberrant GLUTX expression or activity.

Diseases and disorders that are characterized by increased (relative to a subject not suffering from the disease or disorder) levels or biological activity may be treated with Therapeutics that antagonize (i.e., reduce or inhibit) activity. Therapeutics that antagonize activity may be administered in a therapeutic or prophylactic manner. Therapeutics that may be utilized include, but are not limited to, ( ) a GLUTX polypeptide, or analogs, derivatives, fragments or homologs thereof; (ii) antibodies to a GLUTX peptide; (Hi) nucleic acids encoding a GLUTX peptide; (iv) administration of antisense nucleic acid and nucleic acids that are "dysfunctional" (i.e., due to a heterologous insertion within the coding sequences of coding sequences to a GLUTX peptide) that are utilized to "knockout" endogenous function of a GLUTX peptide by homologous recombination (see, e.g., Capecchi, 1989, Science 244:

1288-1292); or (v) modulators (i.e., inhibitors, agonists and antagonists, including additional peptide mimetic of the invention or antibodies specific to a peptide of the invention) that alter the interaction between a GLUTX peptide and its binding partner. Diseases and disorders that are characterized by decreased (relative to a subject not suffering from the disease or disorder) levels or biological activity may be treated with Therapeutics that increase (i e , are agonists to) activity Therapeutics that upregulate activity may be administered in a therapeutic or prophylactic manner Therapeutics that may be utilized include, but are not limited to, a GLUTX peptide, or analogs, derivatives, fragments or homologs thereof, or an agonist that increases bioavailabihty

Increased or decreased levels can be readily detected by quantifying peptide and/or RNA, by obtaining a patient tissue sample (e g , from biopsy tissue) and assaying it in vitro for RNA or peptide levels, structure and/or activity of the expressed peptides (or mRNAs of a GLUTX peptide) Methods that are well-known within the art include, but are not limited to, immunoassays (e g , by Western blot analysis, immunoprecipitation followed by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, immunocytochemistry, etc ) and/or hybridization assays to detect expression of mRNAs (e g , Northern assays, dot blots, in situ hybridization, etc ) In one aspect, the invention provides a method for preventing, in a subject, a disease or condition associated with an abenant GLUTX expression or activity, by admmistenng to the subject an agent that modulates GLUTX expression or at least one GLUTX activity Subjects at risk for a disease that is caused or contributed to by aberrant GLUTX expression or activity can be identified by, for example, any or a combination of diagnostic or prognostic assays as described herein Administration of a prophylactic agent can occur prior to the manifestation of symptoms characteristic of the GLUTX abenancy, such that a disease or disorder is prevented or, alternatively, delayed in its progression Depending on the type of GLUTX abenancy, for example, a GLUTX agonist or GLUTX antagonist agent can be used for treating the subject The appropriate agent can be determined based on screening assays described herein

Another aspect of the invention pertains to methods of modulating GLUTX expression or activity for therapeutic puφoses The modulatory method of the invention involves contacting a cell with an agent that modulates one or more of the activities of GLUTX protein activity associated with the cell An agent that modulates GLUTX protein activity can be an agent as described herein, such as a nucleic acid or a protein, a naturally-occurring cognate ligand of a GLUTX protein, a peptide, a GLUTX peptidomimetic, or other small molecule In one embodiment, the agent stimulates one or more GLUTX protein activity Examples of such stimulatory agents include active GLUTX protein and a nucleic acid molecule encoding GLUTX that has been introduced into the cell In another embodiment, the agent inhibits one or more GLUTX protein activity. Examples of such inhibitory agents include antisense

GLUTX nucleic acid molecules and anti-GLUTX antibodies. These modulatory methods can be performed in vitro (e.g., by culturing the cell with the agent) or, alternatively, in vivo (e.g., by administering the agent to a subject). As such, the present invention provides methods of treating an individual afflicted with a disease or disorder characterized by abenant expression or activity of a GLUTX protein or nucleic acid molecule. In one embodiment, the method involves administering an agent (e.g., an agent identified by a screening assay described herein), or combination of agents that modulates (e.g., upregulates or downregulates) GLUTX expression or activity. In another embodiment, the method involves administering a GLUTX protein or nucleic acid molecule as therapy to compensate for reduced or aberrant GLUTX expression or activity.

The invention will be further illustrated in the following examples, which do not limit the scope of the claims.

EXAMPLES

Example 1. Cloning and Sequence Analysis of GLUTXl

Amino acid sequences of human GLUTs 1-5 (Swiss-Prot accession numbers PI 1 166, PI 1 168, PI 1169, PI 4672 and P22732) were used to screen the Expressed Sequence Tag (EST) data base at NCBI using TBLASTN. Novel ESTs were analyzed using the Genetics Computer Group program suite. ESTs showing significant homology to the GLUTs were identified. Human EST clones 50147 and 46121 (accession numbers H18721 and H09414, respectively) encoding the carboxyl terminus and 3'-untranslated region of GLUTXl were used as probes on rat multiple tissue Northern blots and identified a 2-kilobase transcript that was strongly expressed in testis.

Primers specific for EST H34451 were used to amplify GLUTXl cDNA by 5'- and 3'- RACE from rat testis poly(A)⁺ RNA using Roche Molecular Biochemicals 5' and 3'-RACE reagents. PCR products were cloned using the TOPO cloning system (Invitrogen). For amplification of the full-length GLUTXl sequence, primers were designed from the 5'- and 3'- RACE products and PCR amplification performed using the Expand long template PCR system (Roche Molecular Biochemicals). Three independent reverse transcription-PCR reactions were performed from rat testis poly(A)⁺ RNA, and the resulting products were cloned and sequenced in both directions. Mouse GLUTXl cDNA was determined by sequencing 5'- and 3'-RACE products and mouse EST clones. Human GLUTXl cDNA sequence was determined from sequencing human EST and BAC clones (Research Genetics). A 2087-base paιr cDNA encoding a protein of 478 ammo acids was cloned from rat testis mRNA by RACE as described in the EXAMPLES The ammo acid sequence of GLUTXl compared with eight members of the sugar transport family is presented in FIG 1 The full length sequence of the human GLUTXl cDNA was cloned separately The 5' end was obtained from a BAC clone, thus the sequence upstream of the ATG start codon is part of the gene promoter (see Table 2)

GLUTXl (LL-AA) was constructed from GLUTXl by mutagenesis using a modified 5' primer The resulting cDNA was cloned into pcDNA3 (Invitrogen) and pSD5 vectors for expression analyses See, e g , Geeπng et al 1996 J Cell Biol 133 1 193-1204 Sequence compilations and compaπsons were made using the best fit, gap, and pileup programs

(Genetics Computer Group program suite) and the ClustalX program See, e g , Thompson et al 1997 Nucleic Acids Res 25 4876-4882

Alignment of GLUTXl was made using the pileup (Genetics Computer Group) and ClustalX programs to other members of the GLUT family of proteins, as shown in FIG 1 See, Ibberson et al , 2000 J Biol Chem 275 4607-4612 Black shading indicates identical residues, and gray shading indicates amino acids belonging to the same conservation group The approximate positions of the transmembrane domains are marked The position of a dileucine motif in GLUTXl sequence is indicated by a horizontal bar, and the position of a putative glycosylation site is indicated by an asterisk Four regions of conservation between GLUTXl and integral membrane protein are marked with boxes FIG 2 shows the alignment of the respective human, rat and mouse sequences for GLUTXl (Panel A), GLUTX2 (Panel B) and GLUTX3 (Panel C) Additional alignments and consensus/majority sequences are provided in the various Tables below

Human, rat and mouse GLUTXl sequences are shown in Tables 3A, 3B and 3C, respectively An alignment of human (hXl), rat (rXl) and mouse (mXl) GLUTXl polypeptide sequences is shown in Table 3D The twelve putative TM domains are approximately delineated by the solid line above the aligned sequence In Table 3D, plus all other sequence alignments, fully conserved single residues are indicated by (*), fully conserved "strong" residues are indicated by ( ), and fully conserved "weak" residues are indicated by ( ) The "strong" group of conserved amino acid residues may be any one of the following groups STA, NEQK, NHQK, NDEQ, QHRK, MILV, MILF, HY, FYW The "weak" group of conserved residues may be any one of the following CSA, ATV, SAG, STNK, STPA, SGND, SNDEQK, NDEQHK, NEQHRK, VLIM, HFY The putative glycosylated N residue is indicated by (+). The dileucine repeat is indicated by (o). The

"Majority" GLUTXl polypeptide sequence of Table 3D is disclosed as SEQ ID NO: 15.

TABLE 3A Human GLUTXl Nucleotide (SEQ ID NO:l) and Amino Acid (SEQ ID NO:2) Sequences

CCCGTCTATG GGCTCGCACT ACACTCCAAT TGGGTGGTTG TTCTCCCAGA CGGAAACTCC 60

GCCCCACCTG TACCTTGGAC CGCTCCGCCC TAGGGCGGTT CCAGCGCGCT TCGCTAATCG 120

GTTCTATGCT CCCATTGGTC TGCTTTAATG TAAGGGCGGG TCCTAGCTGA TTCGCTAGCC 180

CCGCCTTGCG TTCCTATTGG CTGCTCCTGC TCTGCGGTTC CGATCCCGCC CAGCACCGTC 240 CCCCACCCCC CGCCGCCCAT TGGCTGCGAG AGGCCGGTGC GGGCCGCACT CGCAGGGCCC 300

GTGGCGGTTC AGGCGCCAGA GCTGGCCGAT CGGCGTTGGC CGCCGACATG ACGCCCGAGG 360 T P E D ACCCAGAGGA AACCCAGCCG CTTCTGGGGC CTCCTGGCGG CAGCGCGCCC CGCGGCCGCC 420 P E E T Q P L L G P P G G S A P R G R R

GCGTCTTCCT CGCCGCCTTC GCCGCTGCCC TGGGCCCACT CAGCTTCGGC TTCGCGCTCG 480 V F A A F A A A L G P L Ξ F G F A L G

GCTACAGCTC CCCGGCCATC CCTAGCCTGC AGCGCGCCGC GCCCCCGGCC CCGCGCCTGG 540

Y S S P A 1 P S L Q R A A P P A P R L D

ACGACGCCGC CGCCTCCTGG TTCGGGGCTG TCGTGACCCT GGGTGCCGCG GCGGGGGGAG 600 D A A A S F G A V V T L G A A A G G V

TGCTGGGCGG CTGGCTGGTG GACCGCGCCG GGCGCAAGCT GAGCCTCTTG CTGTGCTCCG 660

L G G W L V D R A G R K L S L L L C S V TGCCCTTCGT GGCCGGCTTT GCCGTCATCA CCGCGGCCCA GGACGTGTGG ATGCTGCTGG 720

P F V A G F A V I T A A Q D V M L L G

GGGGCCGCCT CCTCACCGGC CTGGCCTGCG GTGTTGCCTC CCTAGTGGCC CCGGTCTACA 780

G R L L T G L A C G V A S L V A P V Y I

TCTCCGAAAT CGCCTACCCA GCAGTCCGGG GGTTGCTCGG CTCCTGTGTG CAGCTAATGG 840 S E I A Y P A V R G L L G S C V Q L M V

TCGTCGTCGG CATCCTCCTG GCCTACCTGG CAGGCTGGGT GCTGGAGTGG CGCTGGCTGG 900 V V G I L L A Y L A G V L E W R W L A

CTGTGCTGGG CTGCGTGCCC CCCTCCCTCA TGCTGCTTCT CATGTGCTTC ATGCCCGAGA 960

V L G C V P P S L M L L L M C F M P E T CCCCGCGCTT CCTGCTGACT CAGCACAGGC GCCAGGAGGC CATGGCCGCC CTGCGGTTCC 1020

P R F L L T Q H R R Q E A M A A L R F L

TGTGGGGCTC CGAGCAGGGC TGGGAAGACC CCCCCATCGG GGCTGAGCAG AGCTTTCACC 1080

W G S E Q G W E D P P I G A E Q S F H L

TGGCCCTGCT GCGGCAGCCC GGCATCTACA AGCCCTTCAT CATCGGCGTC TCCCTGATGG 1140 A L L R Q P G I Y K P F I I G V S L A

CCTTCCAGCA GCTGTCGGGG GTCAACGCCG TCATGTTCTA TGCAGAGACC ATCTTTGAAG 1200 F Q Q L S G V N A V M F Y A E T I F E E AGGCCAAGTT CAAGGACAGC AGCCTGGCCT CGGTCGTCGT GGGTGTCATC CAGGTGCTGT 1260

A K F K D S S L A S V V V G V I Q V L F TCACAGCTGT GGCGGCTCTC ATCATGGACA GAGCAGGGCG GAGGCTGCTC CTGGTCTTGT 1320

T A V A A L I D R A G R R L L L V L S

CAGGTGTGGT CATGGTGTTC AGCACGAGTG CCTTCGGCGC CTACTTCAAG CTGACCCAGG 1380

G V V M V F S T S A F G A Y F K L T Q G

GTGGCCCTGG CAACTCCTCG CACGTGGCCA TCTCGGCGCC TGTCTCTGCA CAGCCTGTTG 1440

G P G N S S H V A I S A P V S A Q P V D

ATGCCAGCGT GGGGCTGGCC TGGCTGGCCG TGGGCAACAT GTGCCTCTTC ATCGCCGGCT 1500 A S V G L A W L A V G N M C L F I A G F

TTGCGGTGGG CTGGGGGCCC ATCCCCTGGC TCCTCATGTC AGAGATCTTC CCTCTGCATG 1560

A V G W G P I P W L L M S E I F P L H V TCAAGGGCGT GGCGACAGGC ATCTGCGTCC TCACCAACTG GCTCATGGCC TTTCTCGTGA 1620

K G V A T G I C V L T N W L A F L V T

CCAAGGAGTT CAGCAGCCTC ATGGAGGTCC TCAGGCCCTA TGGAGCCTTC TGGCTTGCCT 1680

K E F S S L E V L R P Y G A F W L A S

CCGCTTTCTG CATCTTCAGT GTCCTTTTCA CTTTGTTCTG TGTCCCTGAA ATTAAAGGAA 1740 A F C I F S V L F T L F C V P E I K G K

AGACTCTGGA ACAAATCACA GCCCATTTTG AGGGGCGATG ACAGCCACTC ATTAGGGGAT 1800 T L E Q I T A H F E G R

GGAGCAAGCC TGTGACTCCA AGTTGGGCCC AAGCCCAGAG CCCCTGCCTG CCCCAGGGGA 1860

GCCAGAATCC AGCCCCTTGG AGCCTTGGTC TGCAGGGTCC CTCCTTCCTG TCATGCTCCC 1920

TCCAGCCCAT GACCCGGGGC TAGGAGGCTC ACTGCCTCCT GTTCCAGCTC CTGCTGCTGC 1980 TCTGAGGACT CAGGAACACC TTCGAGCTTT GCAGACCTGC GGTCAGCCCT CCATGCGCAA 2040

GACTAAAGCA GCGGAAGAGG AGGTGGGCCT CTAGGATCTT TGTCTTCTGG CTGGAGGTGC 2100

TTTTGGAGGT TGGGTGCTGG GCATTCGGTC GCTCCTCTCA CGCGGCTGCC TTATCGGGAA 2160

GGAAATTTGT TTGCCAAATA AAGACTGACA CAGAAAATCA AAAAAAAAAA AAAAAAA 2217 TABLE 3B

Rat GLUTXl Nucleotide (SEQ ID NO:3) and Amino Acid (SEQ ID NO:4) Sequences cgacagttcg cgggtcagac cctgttgaca tgtcgcccga ggacccccag gaaacacagc 60

M S P E D P Q E T Q P cgctgttgcg gtcgccgggc gccagggctc ccggcggccg ccgggtcttc cttgccacct 120 L L R S P G A R A P G G R R V F L A T F tcgccgccgc cctgggcccg ctcagcttcg gcttcgcgct tggctacagc tcccccgcca 180

A A A L G P L S F G F A L G Y S S P A I tccccagcct gcggcgcacc gcaccccctg ccctacgcct cggagacact gcggcctcct 240

P S L R R T A P P A L R L G D T A A S W ggttcggggc cgtcgtgacc ctgggcgctg cggcaggggg cgtgctgggc ggctggctcc 300 F G A V V T L G A A A G G V L G G W L L tggaccgtgc agggcgcaag ctgagcctcc tgctctgcac cgtgcccttc gtgaccggtt 360 D R A G R K L S L L L C T V P F V T G F ttgctgtcat caccgcggcc cgggatgtgt ggatgctgct cggaggccgc ctcctcaccg 420

A V I T A A R D V W M L L G G R L L T G gcctagcctg cggagtcgcc tcattagtgg caccggtcta tatctcggaa atcgcctacc 480

L A C G V A S L V A P V Y I S E I A Y P cagccgttcg aggactgctc ggctcctgtg tgcagctgat ggttgtcact ggcatcctct 540 A V R G L L G S C V Q L M V V T G I L L tggcctacgt ggcaggctgg gtcctagaat ggcgctggtt ggctgtgctg ggctgtgtgc 600

A Y V A G W V L E W R W L A V L G C V P cccccaccct catgctgctg ctcatgtgct acatgcccga gaccccacgc ttcctcctga 660

P T L M L L L M C Y M P E T P R F L L T cgcaacacca gtaccaggag gccatggctg ccctgcgctt cctgtggggc tctgaggagg 720

Q H Q Y Q E A M A A L R F L W G S E E G gctgggaaga gccccctgtt ggggctgagc accagggctt ccagctggct atgctgaggc 780 W E E P P V G A E H Q G F Q L A M L R R gccctggtgt ccacaagccc ctcatcatcg gcatttgcct catggtcttc cagcagctgt 840 P G V H K P L I I G I C L M V F Q Q L S caggggtcaa cgccatcatg ttctatgcca acaccatctt tgaggaggcc aagttcaagg 900

G V N A I M F Y A N T I F E E A K F K D acagcagcct ggcctcggtc actgtgggca tcatccaggt tctgttcact gctgtggcgg 960

S S L A S V T V G I I Q V L F T A V A A ccctcatcat ggacagagca gggcgaaaac tgcttctggc cttgtcgggt gtgatcatgg 1020

L I M D R A G R K L L L A L S G V I M V ttttcagcat gagcgccttt ggtacctact tcaaactgac ccagagtggc cccagcaact 1080 F S M S A F G T Y F K L T Q S G P S N S cctcccatgt aggcctcctg gtgcccatct ccgcagagcc tgctgatgtt cacctggggc 1140 S H V G L L V P I S A E P A D V H L G L tggcctggct ggctgtaggc agcatgtgcc tcttcatcgc tggttttgca gtaggctggg 1200

A W L A V G S M C L F I A G F A V G W G gacccatccc ctggctcctc atgtcagaga tcttccctct gcacatcaag ggtgtggcta 1260 P I P W L L M S E I F P L H I K G V A T ccggcgtctg tgtcctcacc aactggttca tggcctttct ggtgaccaaa gagtttaaca 1320

G V C V L T N W F M A F L V T K E F N S gcatcatgga gatcctcaga ccctacggcg ccttctggct caccgctgcc ttctgtatcc 1380

I M E I L R P Y G A F W L T A A F C I L tcagcgtcct tttcacgctc acctttgtcc ctgagactaa aggcaggact ctggaacaaa 1440 S V L F T L T F V P E T K G R T L E Q I tcacagccca tttcgaggga cggtgacgga ccctttctgt gactggcagc cctgagctga 1500

T A H F E G R gctggcttcg ggtttcaaaa ggagtggagt ggcctcagtg accacagttt gagcccaggg 1560 gccccctgac tcctcagatc tccgggccag ctttgtccag atctcaaccc agatccacac 1620 catgagcttc accagattct gaggctctgc agcctgctgc acacacagca catctgcgga 1680 gccatgcagt ctcgcctaac ccacgggtct ccttcctaag actaaagcaa ctgacgagac 1740 tgcgggctcc tggctctagt gctctggctg ggcatctttg gggtgcttgg tcctaagcaa 1800 ctgcccatac ctcacttgac tgggggatga gaaagggact tagccacata agatttgggc 1860 tcagaaacaa ggtcaggtga gtccaggaag aaaagagaat gttcttgtct tgtcaaccaa 1920 gtccttctca gagtgcccag agacctccgg attcaccttg gggttagcca gcttacccat 1980 cacttacagg ttctctccaa ctcttccctg gtctcagtgt cctggatcat tagtcaccag 2040 gtcttgttga gtttcagaaa ataaaaggcc tctttccgtt caacttt 2087

TABLE 3C Mouse GLUTXl Nucleotide (SEQ ID NO:5) and Amino Acid (SEQ ID NO:6) Sequences

GCGGGTCAGG TCCTGCTGAC ATGTCTCCCG AGGACCCCCA GGAGACGCAG CCGCTATTGC 60

M S P E D P Q E T Q P L L R

GGCCACCGGA AGCCAGGACT CCCCGCGGCC GCCGGGTCTT CCTCGCTTCC TTCGCCGCCG 120

P P E A R T P R G R R V F L A S F A A A

CTCTGGGACC CCTCAACTTC GGCTTCGCGC TCGGCTACAG CTCCCCCGCC ATCCCCAGCC 180 L G P L N F G F A L G Y S S P A I P S L

TGCGGCGCAC CGCACCCCCG GCCCTGCGCC TCGGAGACAA TGCGGCCTCC TGGTTCGGGG 240 R R T A P P A L R L G D N A A S W F G A

CCGTCGTGAC CCTGGGCGCT GCTGCAGGGG GCATACTGGG CGGCTGGCTC CTGGACCGTT 300

V V T L G A A A G G I L G G W L L D R S CAGGGCGCAA GCTGAGCCTC TTGCTCTGCA CCGTGCCCTT CGTGACTGGC TTTGCTGTCA 360

G R K L S L L L C T V P F V T G F A V I

TCACCGCGGC CCGGGATGTG TGGATGCTGC TCGGAGGCCG CCTCCTCACC GGCCTTGCCT 420

T A A R D V W M L L G G R L L T G L A C

GCGGAGTCGC CTCACTAGTG GCACCGGTTT ACATCTCGGA AATCGCCTAC CCAGCTGTCC 480 G V A S L V A P V Y I S E I A Y P A V R

GAGGACTGCT CGGCTCCTGT GTGCAGCTGA TGGTTGTCAC TGGCATCCTC CTGGCCTATG 540 G L L G S C V Q L M V V T G I L L A Y V

TGGCAGGCTG GGTCCTAGAG TGGCGCTGGC TGGCCGTGCT GGGCTGTGTG CCCCCCACCC 600

A G W V L E W R W L A V L G C V P P T L TCATGCTGCT GCTCATGTGC TACATGCCCG AGACCCCACG TTTTCTCCTC ACTCAACACC 660

M L L L M C Y M P E T P R F L L T Q H Q

AGTACCAGGA GGCCATGGCT GCCTTGCGCT TCCTGTGGGG CTCTGAGGAG GGCTGGGAAG 720

Y Q E A M A A L R F L W G S E E G W E E

AGCCCCCTGT TGGGGCTGAG CACCAGGGCT TCCAGCTGGC CCTGCTGAGG CGCCCTGGCA 780 P P V G A E H Q G F Q L A L L R R P G I

TCTACAAGCC CCTCATCATC GGCATTTCCC TCATGGTCTT CCAGCAGCTG TCAGGGGTCA 840 Y K P L I I G I S L M V F Q Q L S G V N

ATGCTATCAT GTTCTATGCC AACAGCATCT TCGAGGAGGC CAAGTTCAAG GACAGCAGCC 900 A I M F Y A N S I F E E A K F K D S S L

TGGCCTCGGT CACTGTGGGC ATAATCCAGG TCCTGTTCAC TGCTGTGGCG GCCCTCATCA 960

A S V T V G I I Q V L F T A V A A L I M

TGGACAGAGC AGGGCGAAGG CTGCTCCTGG CCTTGTCGGG TGTGATCATG GTGTTCAGTA 1020

D R A G R R L L L A L S G V I M V F S M

TGAGTGCCTT TGGTACCTAC TTCAAACTGA CCCAGAGCCT CCCCAGCAAC TCCTCCCACG 1080 S A F G T Y F K L T Q S L P S N S S H V

TAGGCCTGGT GCCCATCGCG GCGGAGCCTG TGGATGTCCA AGTGGGACTG GCCTGGCTGG 1140

G L V P I A A E P V D V Q V G L A W L A CTGTAGGCAG CATGTGCCTC TTCATTGCTG GCTTTGCGGT GGGCTGGGGA CCCATCCCCT 1200

V G S M C L F I A G F A V G W G P I P W

GGCTCCTCAT GTCAGAGATC TTCCCTCTGC ATGTCAAGGG TGTGGCTACC GGCATCTGTG 1260

L L M S E I F P L H V K G V A T G I C V

TCCTCACCAA CTGGTTCATG GCCTTTCTAG TGACCAAAGA GTTCAACAGC GTCATGGAGA 1320 L T N W F M A F L V T K E F N S V M E M

TGCTCAGACC CTACGGTGCC TTCTGGCTCA CCGCTGCCTT CTGCGCTCTC AGTGTCCTAT 1380 L R P Y G A F W L T A A F C A L S V L F

TCACACTGAC CGTTGTCCCT GAGACTAAAG GCAGGACTCT GGAACAAGTC ACAGCCCATT 1440 T L T V V P E T K G R T L E Q V T A H F TCGAGGGACG ATGACAGACC CTTTCTGTGC CTGGGAGCCC CGAGCTGAGC TGCCTTTGGG 1500 E G R

TTTCAGAAGG AGTGGAGTGG CCTGTAACTA AGCCACACCT CAGTTTGAGC CTGGAGGCCC 1560

CTGACTCCTC ACCTCAGGGC CCTCTTTGCC CAGATCTCAA CCCAGATTCC CACCGTGAGC 1620 CCACCAGACT CTGAGTGCGG TCTCTGCAGC CTGCTTCACA CACAGGACAT CTGAGGAGCT 1680

GTGCATCCTC ACCTGACCCA GGTGTCTCCT TCTTAAGACT GAGGCAGCTG AAGGGACCTG 1740

AGGGCTCCTG GCTCCCGTTT CCTGGCTGGG GTGCCCGGTC CTAAGCAGCC GCCTGTACCT 1800

CACTTGACTG GGAGATCAGA AAGGGACTTA GCCATATGGG CTCAGAAACA AGGTCAGGTG 1860

AGCCCAGGTA GAAGAGAGAA TGTTCTTGCC AACCAAGCCC TCCTCAGAGC TGCGCAGAGA 1920 CTCTCCGGGG TCACCCTGGG GCCAGCCAGC TTACCCATCA CTTACAGGTT CTTTCTGGCT 1980

CTTTCCTGGG CTCCGTGTCC TGGGTCATTA GCCACCATAT CTTGTTGAGT TTCAGGAAAT 2040

AAAAAGCCTC TTACTGTTCA AAAAAAAACA AA 2072

TABLE 3D Sequence alignment of rat, human and mouse GLUTXl polypeptides and

Majority GLUTXl Sequence (SEQ ID NO:15) oo TM1 mXl MSPEDPQETQPLLRPPEARTPRGRRVFLASFAAALGPLNFGFALGYSSPAIPSLRRTAPP rXl MSPEDPQETQPLLRSPGARAPGGRRVFLATFAAALGPLSFGFALGYSSPAIPSLRRTAPP hXl MTPEDPEETQPLLGPPGGSAPRGRRVFLAAFAAALGPLSFGFALGYSSPAIPSLQRAAPP

Majority MsPEDPqETQPLLrpPgaraPrGRRVFLAaFAAALGPLsFGFALBYSSPAIPSLrRtAPP TM2 TM3 mXl ALRLGDNAASWFGAWTLGAAAGGILGGWLLDRSGRKLSLLLCTVPFVTGFAVITAARDV rXl ALRLGDTAASWFGAVVTLGAAAGGVLGGWLLDRAGRKLSLLLCTVPFVTGFAVITAARDV hXl APRLDDAAASWFGAVVTLGAAAGGVLGGWLVDRAGRKLSLLLCSVPFVAGFAVITAAQDV * * * -k **************** * . ***** . ** . ********* . **** . ******** . **

Majority AlRLgDaAAS FGA VTLGAAAGGvLGGWLlDRaGRKLSLLLCtVPFVtGFAVITAArDV

TM4 TM5 mXl WMLLGGRLLTGLACGVASLVAPVYISEIAYPAVRGLLGSCVQLMVVTGILLAYVAG VLE rXl WMLLGGRLLTGLACGVASLVAPVYISEIAYPAVRGLLGSCVQLMVVTGILLAYVAG VLE hXl WMLLGGRLLTGLACGVASLVAPVYISEIAYPAVRGLLGSCVQLMVVVGILLAYLAGWVLE

_******_*****_******_***_*****_**************_*****_** _****** - ******

Majority WMLLGGRLLTGLACGVASLVAPVYISEIAYPAVRGLLGSCVQLMVVtGILLAYvAGWVLE

TM6 mXl WR LAVLGCVPPTLMLLLMCYMPETPRFLLTQHQYQEAMAALRFLWGSEEGWEEPPVGAE rXl WRWLAVLGCVPPTLMLLLMCYMPETPRFLLTQHQYQEAMAALRFLWGSEEGWEEPPVGAE hXl WR LAVLGCVPPSLMLLLMCFMPETPRFLLTQHRRQEAMAALRFL GSEQGWEDPPIGAE

*_**_**_****_*** . _**_***_** . *_***_***_***_** . _*****_***_****** . * * * . * * . * * *

Majority WR LAVLGCVPPtLMLLLMCyMPETPRFLLTQHqyQEAMAALRFL GSEeGWEePPvGAE

TM7 mXl HQGFQLALLRRPGIYKPLIIGISLMVFQQLSGVNAIMFYANSIFEEAKFKDSSLASVTVG rXl HQGFQLAMLRRPGVHKPLIIGICLMVFQQLSGVNAIMFYANTIFEEAKFKDSSLASVTVG hXl QS-FHLALLRQPGIYKPFIIGVSLMAFQQLSGVNAVMFYAETIFEEAKFKDSSLASVVVG

*.**._**.*_*.._**,**_*. _* * _*********._****..****_****_******* * *

Majority hqgFqLAlLRrPGiyKPHIGisLMvFQQLSGVNAiMFYAnt IFEEAKFKDSSLASVtVG TM8 TM9 + mXl I IQVLFTAVAALIMDRAGRRLLLALSGVIMVFSMSAFGTYFKLTQSLPSNSSHVG-LVPI rXl I IQVLFTAVAALIMDRAGRKLLLALSGVIMVFSMSAFGTYFKLTQSGPSNSSHVGLLVPI hXl VIQVLFTAVAALIMDRAGRRLLLVLSGVVMVFSTSAFGAYFKLTQGGPGNSSHVAISAPV

.******************. * * * ********* *_*****_**_*** * * * * * * * . Majority llQVLFTAVAALIMDRAGRrLLLaLSGViMVFSmSAFGtYFKLTQsgPsNSSHVgilvPi TM10 TM11 mXl AAEPVDVQVGLAWLAVGSMCLFIAGFAVGWGPIPWLLMSEIFPLHVKGVATGICVLTNWF rXl SAEPADVHLGLAWLAVGSMCLFIAGFAVGWGPIPWLLMSEIFPLHIKGVATGVCVLTNWF hXl SAQPVDASVGLAWLAVGNMCLFIAGFAVGWGPIPWLLMSEIFPLHVKGVATGICVLTNWL

. * . -k * . ******* * *************************** • ****** . ****** .

Majority sAePvDvsvGLAWLAVGsMCLFIAGFAVGWGPI PWLLMSEIFPLHvKGVATGiCVLTNWf TM12 mXl MAFLVTKEFNSVMEMLRPYGAFWLTAAFCALSVLFTLTVVPETKGRTLEQVTAHFEGR rXl MAFLVTKEFNSIMEILRPYGAFWLTAAFCILSVLFTLTFVPETKGRTLEQITAHFEGR hXl MAFLVTKEFSSLMEVLRPYGAFWLASAFCIFSVLFTLFCVPEIKGKTLEQITAHFEGR

_**_******* *._**._*******_**..*_** ***_***_* * * * **.****.*******

Majority MAFLVTKEFnSlMEvLRPYGAFWLtaAFCilSVLFTLtcVPEtKGrTLEQiTAHFEGR

Similar methodologies were used to clone human and rat GLUTX2, as shown in Table 4A and 4B. An alignment of human (hX2) and rat (rX2) GLUTX2 is shown in Table 4C. The twelve putative TM domains are approximately delineated by the solid line above the aligned sequence. In Table 4C, fully conserved single residues are indicated by (*), fully conserved "strong" residues are indicated by (:). and fully conserved "weak" residues are indicated by (.). The putative glycosylated N residue is indicated by (+).The dileucine repeat is indicated by (o). The "Majority" GLUTX2 polypeptide sequence is disclosed as SEQ ID NO: 16. TABLE 4A

Human GLUTX2 Polynucleotide (SEQ ID NO:7) and Amino Acid (SEQ ID NO:8)

Sequences Sequence Range: 1 to 2177; Coding Region: 288 to 2174

1 actatagggc gaattgggta ccgggccccc cctcgaggtc gacggtatcg ataagcttga

61 tatcgaattc cggccgtggc ggcggctgct gccgtggcag ccggagcgga agccgggagg

121 aagaaagcgg cggcagcggc ggttgctccc gccggctcgg gctgtctagc tcgccgagac 181 tgccggcccg cggagccgcg tccccccggg cagccccggg cccctgccct atgtcccgca

241 aggcaagcga gaatgtggag tacacgctgc ggagcctgag cagcctgatg ggcgagcggc

M G E R R 301 gcaggaagca gccggagccg gacgcggcga gcgcggccgg ggagtgcagc ctcctggctg

R K Q P E P D A A S A A G E C S L L A A

361 ccgccgaatc gagcaccagc ctgcagagcg cgggcgcggg cggcggcggc gtcggggacc

A E S S T S L Q S A G A G G G G V G D L

421 tggagcgcgc ggcgcggcgg cagttccagc aggacgagac ccccgccttc gtgtacgtgg

E R A A R R Q F Q Q D E T P A F V Y V V

481 tggccgtctt ctccgcgctg ggcggcttcc tgtttggcta tgacaccggg gtggtgtcag A V F S A L G G F L F G Y D T G V V S G

541 gggccatgct gctgctcaag cggcagctca gtctggacgc gctgtggcag gagctgctgg A M L L L K R Q L S L D A L W Q E L L V 601 tgtccagcac ggtgggggcg gctgccgtct cggcgctggc cggaggcgcc ctcaacggcg S S T V G A A A V S A L A G G A L N G V

661 tcttcggccg ccgcgctgcc atcctcctgg ccagtgccct cttcaccgcc ggctccgcgg

F G R R A A I L L A S A L F T A G S A V

721 tgctggctgc ggccaacaac aaggagacac tgctcgccgg ccgcctggtc gtgggactcg

L A A A N N K E T L L A G R L V V G L G

781 gcatcggcat tgcttctatg acagtgccag tgtacattgc ggaggtctca ccacccaatt I G I A S M T V P V Y I A E V S P P N L

841 taagaggccg attagtcacc attaataccc tcttcatcac aggagggcag ttctttgcaa R G R L V T I N T L F I T G G Q F F A S

901 gtgttgttga tggagccttc agttatctcc agaaggatgg atggaggtac atgttgggac V V D G A F S Y L Q K D G R Y M L G L

961 ttgcagcagt tccggcggtt atacagtttt ttggctttct ctttttgcct gaaagccctc

A A V P A V I Q F F G F L F L P E S P R

1021 gatggcttat tcagaaagga cagactcaga aggcccgtag aattttatct cagatgcgtg

W L I Q K G Q T Q K A R R I L S Q M R G

1081 gtaaccagac cattgatgag gaatatgata gcatcaaaaa caacattgaa gaggaggaaa N Q T I D E E Y D S I K N N I E E E E K

1141 aagaggttgg ctcagctgga cctgtgatct gcagaatgct gagttatccc ccaactcgcc

E V G S A G P V I C R M L S Y P P T R R 1201 gagctttaat tgtgggttgt ggcctacaaa tgttccagca gctctcaggc attaacacca

A L I V G C G L Q M F Q Q L S G I N T I 1261 tcatgtacta cagtgcaacc attctgcaga tgtctggtgt tgaagatgat agacttgcaa

M Y Y S A T I L Q M S G V E D D R L A I

1321 tatggctggc ttcagttaca gccttcacaa atttcatttt cacacttgtg ggagtctggc

W L A S V T A F T N F I F T L V G V W L

1381 ttgttgagaa ggtgggccgc agaaagctta cctttggtag tttagcaggt accaccgtag

V E K V G R R K L T F G S L A G T T V A

1441 cactcattat tcttgccttg ggatttgtgc tatcagccca agtttcccca cgcatcactt

L I I L A L G F V L S A Q V S P R I T F

1501 ttaagccaat agctccgtca ggtcagaacg ccacttgcac aagatacagt tactgtaatg K P I A P S G Q N A T C T R Y S Y C N E

1561 aatgtatgtt ggatccagac tgcggtttct gctacaagat gaacaaatca actgtcattg C M L D P D C G F C Y K M N K S T V I D 1621 actcctcctg tgttccagtt aataaagcat ctacaaatga ggcagcctgg ggcaggtgtg

S S C V P Y N K A S T N E A A W G R C E

1681 aaaatgaaac caagttcaaa acagaagata tattttgggc ttacaatttc tgccctactc

N E T K F K T E D I F W A Y N F C P T P

1741 catactcctg gactgcactt ctgggcctta ttttatatct tgtcttcttt gcacctggaa

Y S T A L L G L I L Y L V F F A P G M

1801 tgggaccaat gccttgga t gtgaattctg aaatatatcc cctttgggca agaagtacag G P M P W T V N S E I Y P L W A R S T G

1861 gaaatgcatg ttcatctgga ataaactgga ttttcaatgt cctggtttca ctaacatttt N A C S S G I N W I F N V L V S L T F L 1921 tacacacagc agagtatctt acatactatg gagctttctt cctctatgct ggatttgctg H T A E Y L T Y Y G A F F L Y A G F A A

1981 ctgtgggact ccttttcatc tatggctgtc ttcctgagac caaaggcaaa aaattagagg V G L L F I Y G C L P E T K G K K L E E

2041 aaattgaatc actctttqac aacaggctat gtacatgtgg cacttcagat tctgatgaag I E S L E D N R L C T C G T S D S D E G

2101 ggagatatat tgaatatatc cgcgtgaagg gaagtaacta ccatctctcc gacaacgacg R i' I E Y I R V K G S N Y H L S D N D A

2161 cctcggacgt ggagtga S D V E TABLE 4B

Rat GLUTX2 Polynucleotide (SEQ ID NO:9) and Amino Acid (SEQ ID NO:10)

Sequences

GGCACGAGGC GGCTCAGCAG CTGGCAGCGA GTGCGCGGCG CCCCACGGAA CTTCCCCGCA 60

GCCGCCCGGG CGGCGTCCGT CTGTCCCATG TCCCGCAAGG CGAGCGAGGA CGTGGAGTAC 120

ACGCTGCGCA GCCTGAGCAG CCTGATGGGC GAGAGGCGCC GCCGGCAGCC GGAGCCCGGG 180

M G E R R R R Q P E P G

GCGCCGGGCG GGGAGCGCAG CCTCCTGGCC GCCGAGTCGG CCGCCAGCCT GCAGGGCGCG 240 A P G G E R S L L A A E S A A S L Q G A GAGCTGGAGC GCGCGGCGCG CAGGCAGTTC CAGCGCGACG AGACCCCCGC CTTCGTGTAC 300

E L E R R R Q F Q R D E T P A F V Y GCGGCCGCCG CCTTCTCCGC TCTCGGCGGC TTCCTGTTCG GCTACGACAC CGGCGTGGTG 360

A A A A F S A L G G F L F G Y D T G V V

TCGGGGGCCA TGCTGCTGCT GCGGCGCCAG ATGCGCCTGG GCGCGATGTG GCAGGAGCTG 420

S G A M L L L R R Q M R L G A M W Q E L

CTGGTGTCGG GCGCGGTGGG CGCGGCCGCC GTCGCGGCGC TGGCCGGAGG GGCCCTGAAC 480

L V S G A V G A A A V A A L A G G A L N

GGCGCCCTCG GTCGGCGAAG CGCCATCCTG CTGGCCAGCG CCCTGTGCAC CGTGGGCTCC 540 G A L G R R S A I L L A S A L C T V G S

GCCGTGCTGG CCGCCGCCGC CAACAAGGAG ACGCTGCTGG CCGGCCGCCT GGTCGTGGGG 600

A V L A A A A N K E T L L A G R L V V G CTCGGCATCG GCATCGCATC CATGACAGTG CCCGTGTACA TCGCCGAGGT CTCTCCACCC 660

L G I G I A S M T V P V Y I A E V S P P

AACCTGAGAG GTCGCTTGGT CACCATCAAC ACCCTCTTCA TCACCGGCGG ACAGTTCTTT 720

N L R G R L V T I T L F I T G G Q F F

GCGAGCGTTG TTGATGGAGC CTTTAGTTAC CTGCAGAAGG ATGGATGGAG GTACATGTTG 780 A S V V D G A F S Y L Q K 3 G W R Y M L

GGACTTGCGG CCATTCCAGC CGTTATACAA TTCCTCGGAT TCCTCTTTTT GCCCGAAAGT 840 G L A A I P A V I Q F L G F L F L P E S

CCTCGGTGGC TGATACAGAA AGGACAGACT CAGAAGGCCC GCCGAATTTT GTCCCAGATG 900

P R W L I Q K G Q T Q K A R R I L S Q M CGTGGGAATC AGACCATTGA CGAGGAGTAT GACAGCATCA GGAACAGCAT CGAGGAGGAG 960

R G N Q T I D E E Y D S I R N S I E E E

GAGAAGGAAG CCAGCGCAGC TGGACCTATA ATCTGCAGAA TGCTGAGTTA CCCCCCAACT 1020

E K E A S A A G P I I C R M L S Y P P T

CGCCGAGCGT TAGCTGTGGG ATGTGGCTTA CAGATGTTCC AGCAGCTCTC GGGCATCAAC 1080 R R A L A V G C G L Q M F Q Q L S G I N

ACTATCATGT ACTACAGCGC GACCATCCTG CAGATGTCCG GCGTGGAAGA TGATAGACTT 1140 1 I M Y Y S A T I L Q M S G V E D D R L

GCAATATGGC TGGCTTCCAT TACAGCGTTC ACCAATTTCA TTTTCACACT GGTGGGCGTC 1200

A I W L A S I T A F T N F I F T L V G V TGGCTCGTGG AGAAGGTGGG CCGCAGGAAG CTCACCTTTG GCAGTTTGGC AGGTACCACA 1260

W L V E K V G R R K L T F G S L A G T T

GTAGCACTTA CAATTCTTGC CTTGGGATTT CTGCTCTCAG CTCAGGTCTC ACCACGGGTC 1320

V A L T I L A L G F L L S Q V S P R V

ACTTTCAGAC CAACGGCTCC CTCGGGTCAA AATGCCACCT GCACAGAATA CAGTTACTGT 1380 T F R P T A P S G Q N A T C T E Y S Y C

AATGAGTGTA TGCTGGATCC AGACTGCGGT TTCTGCTACA AGATCAACAG TTCGGCTGTC 1440 N E C M L D P D C G F C Y K I N S S A V

ATTGATTCCT CCTGTGTTCC GGTGAACAAA GCTTCCACCA ATGAAGCAGC CTGGGGCAGG 1500 I D S S C V P V N K A S T N E A A W G R TGTGAAAACG AAACCAAGTT CAAAGCAGAA GATGTTCACT GGGCTTACAG TTTCTGCCCT 1560

C E N E T K F K E D V H W A Y S F C P

ACCCCATACT CCTGGACAGC ACTCGTGGGC CTGGTGTTAT ATCTTGTTTT CTTTGCACCC 1620

T P Y S T A L V G L V L Y L V F F A P

GGAATGGGAC CAATGCCCTG GACCGTGAAC TCTGAAATCT ATCCTCTCTG GGCAAGAAGT 1680

G M G P M P W T V N S E I Y P L W A R S

ACAGGAAATG CGTGCTCAGC TGGAATAAAC TGGATTTTCA ACGTGCTGGT TTCACTGACC 1740

T G N A C S A G I N W I F N V L V S L T

TTTTTACACA CAGCGGAGTA TCTTACATAC TATGGAGCGT TCTTCCTCTA CGCCGGATTC 1800 F L H T A E Y L T Y Y G A F F L Y A G F

GCCGCTGTGG GACTGCTTTT CGTCTATGGC TGTCTTCCTG AAACCAAAGG GAAAAAACTA 1860

A A V G L L F V Y G C L P E T K G K K L GAGGAAATCG AATCGCTCTT CGACCACCGG CTGTGCACCT GCGGCACCGC GGACTCGGAC 1920

E L 1 E S L E D r. K L C T C G T A D S D

GAGGGCAGGT ACATCGAGTA CATCCGCGTG AAGGGAAGTA ACTACCATCT CTCCGACAAC 1980

E G R Y I E Y I R V K G S N Y H L S D N

GACGCCTCGG ACGTGGAGTG ACTTCCACCC GATGGCTTTC CAGTTACTGA AGTGAACGTG 2040 D A S D V E

TCGGGAAGGC CAGCGGTTGG TCACTGCCCT GCTCACAAGC CGAGTCTCCC CACCGTCCTT 2100 GCCAATGACT CCATATTCCA GAAGACTTGA TGAGCAGAAA AATACAACTC TGGTGATGTT 2160 TATTTTCATA CACAGAAATG CTAAAAAAAA AAAATAAATA AATAACCACA GATTTTTCTT 2220 AGGCAAATGT GTACAAGCCC TTCCCGAGAC AATCTAAACA CTACTGTTGT ACCCAGCGAC 2280 TTCAGTTGGG GTCCCTTTCT CCTTAAACCA CACAT ATTA GTGGCAATAC AGTCAGTGCT 2340 TACCTAGGCA GATTATTTAC GTATATTTAT AAAGGATTAT TTAAAACGAT CTAAGAATAT 2400 TTAATGTCAA AACACGGCCT ATTGACCCTA AATTTTCATA TCAGGTAGTG GCTTTTCTCT 2460 GATCAGTACA GAGTGAATCC CATCTAAACT TCCCCCTCGT GCCG 2504

TABLE 4C

Sequence alignment of human and rat GLUTX2 protein sequences and Majority GLUTX2 Sequence (SEQ ID NO:16) oo hX2 MGERRRKQPEPDAASAAGECSLLAAAESSTSLQSAGAGGGGVGDLERAARRQFQQDETPA rX2 MGERRRRQPEP--GAPGGERSLLAA-ESAASLQGA ELERAARRQFQRDETPA

Majority MGERRRkQPEPdaasaaGECSLLAAAESSTSLQSAgaggggvgdLERAARRQFQqDETPA

TM1 TM2 hX2 FVY VAVFSALGGFLFGYDTGVVSGAMLLLKRQLSLDALWQELLVSSTVGAAAVSALAGG rX2 FVYAAAAFSALGGFLFGYDTGVVSGAMLLLRRQMRLGAMWQELLVSGAVGAAAVAALAGG

Majority FVY vAvFSALGGFLFGYDTGVVSGAMLLLkRQlsLdAlWQELLVSsTVGAAAVsALAGG TM3 TM4 hX2 ALNGVFGRRAAILLASALFTAGSAVLAAANNKETLLAGRLVVGLGIGIASMTVPVYIAEV rX2 ALNGALGRRSAILLASALCTVGSAVLAAAANKETLLAGRLVVGLGIGIASMTVPVYIAEV

* * _* * ._***.**_***_*** _{* **}*_***_** *_*****_*******_********_********_*

Majority ALNGvfGRRaAILLASALfTaGSAVLAAAnNKETLLAGRL VGLGIGIASMTVPVYIAEV TM5 TM6 hX2 SPPNLRGRLVTINTLFITGGQFFASVVDGAFSYLQKDGWRYMLGLAAVPAVIQFFGFLFL rX2 SPPNLRGRLVTINTLFITGGQFFASVVDGAFSYLQKDGWRYMLGLAAIPAVIQFLGFLFL

*********************************************** . * + + *-*-* . * * * * * Majority SPPNLRGRLVTINTLFITGGQFFASWDGAFSYLQKDGWRYMLGLAAvPAVIQFfGFLFL hX2 PESPRWLIQKGQTQKARRILSQMRGNQTIDEEYDSIKNNIEEEEKEVGSAGPVICRMLSY rX2 PESPRWLIQKGQTQKARRILSQMRGNQTIDEEYDSIRNSIEEEEKEASAAGPIICRMLSY

*_********_{******************}**_**_**_**_** _{* *}*_***_** . * _* * . _******* Maj ority PESPRWLIQKGQTQKARRILSQMRGNQTIDEEYDSIkNnlEEEEKEvgsAGPvICRMLSY TM7 TM8 hX2 PPTRRALIVGCGLQMFQQLSGINTIMYYSATILQMSGVEDDRLAIWLASVTAFTNFIFTL rX2 PPTRRALAVGCGLQMFQQLSGINTIMYYSATILQMSGVEDDRLAIWLASITAFTNFIFTL ******* ****************************************** **********

Majority PPTRRALiVGCGLQMFQQLSGINTIMYYSATILQMSGVEDDRLAIWLASvTAFTNFIFTL TM9 hX2 VGVWLVEKVGRRKLTFGSLAGTTVALIILALGFVLSAQVSPRITFKPIAPSGQNATCTRY rX2 VGVWLVEKVGRRKLTFGSLAGTTVALTILALGFLLSAQVSPRVTFRPTAPSGQNATCTEY

Majority VGVWLVEKVGRRKLTFGSLAGTTVALiILALGFvLSAQVSPRiTFkPiAPSGQNATCTrY

+ hX2 SYCNECMLDPDCGFCYKMNKSTVIDSSCVPVNKASTNEAAWGRCENETKFKTEDIFWAYN rX2 SYCNECMLDPDCGFCYKINSSAVIDSSCVPVNKASTNEAAWGRCENETKFKAEDVHWAYS

_{*****************} . * * . *_**_********_********_**_***_***** . _* * . * * *

Majority SYCNECMLDPDCGFCYKmNkStVIDSSCVPVNKASTNEAAWGRCENETKFKtEDifWAYn TM10 TM11 hX2 FCPTPYSWTALLGLILYLVFFAPGMGPMPWTVNSEIYPLWARSTGNACSSGINWIFNVLV rX2 FCPTPYSWTALVGLVLYLVFFAPGMGPMPWTVNSEIYPLWARSTGNACSAGINWIFNVLV

_*********_** . _{* *} . _**_****_***_*******_***_***_******_****** . ***_***_***_*

Majority FCPTPYSWTALlGLiLYLVFFAPGMGPMPWTVNSEIYPLWARSTGNACSsGINWIFNVLV

TM12 hX2 SLTFLHTAEYLTYYGAFFLYAGFAAVGLLFIYGCLPETKGKKLEEIESLFDNRLCTCGTS rX2 SLTFLHTAEYLTYYGAFFLYAGFAAVGLLFVYGCLPETKGKKLEEIESLFDHRLCTCGTA

_********_***_*******_*****_******_* . *_*****_************** • *_****** . Majority SLTFLHTAEYLT^ YGAFFLYAGFAAVGLLFiYGCLPETKGKKLEEIESLFDnRLCTCGTs hX2 DSDEGRYIEYIRVKGSNYHLSDNDASDVE rX2 DSDEGRYIEYIRVKGSNYHLSDNDASDVE

*_**_*********_***********_****** Majority DSDEGRYIEYIRVKGSNYHLSDNDASDVE

Similar methodologies were used to clone human and rat GLUTX3, as shown in Tables 5 A and 5B. An alignment of human (hX3) and rat (rX3) GLUTX3 is shown in Table 5C. The twelve putative TM domains are approximately delineated by the solid line above the aligned sequence. In Table 5C, fully conserved single residues are indicated by (*), fully conserved "strong" residues are indicated by (:), and fully conserved "weak" residues are indicated by (.). The putative glycosylated N residue is indicated by (+). The dileucine repeat is indicated by (o). The "Majority" GLUTX3 polypeptide sequence is disclosed as SEQ ID NO:17. TABLE 5A

Human GLUTX3 Polynucleotide (SEQ ID NO:ll) and Amino Acid (SEQ ID NO:12)

Sequences

1 gcccttggcc atgcaggagc cgctgctggg agccgagggc ccggactacg acaccttccc

M Q E P L L G A E G P D Y D T F P

61 cgagaagccg cccccgtcgc caggggacag ggcgcgggtc gggaccctgc agaacaaaag

E K P P P S P G D R A R V G T L Q N K R

121 ggtgttcctg gccaccttcg ccgcagtgct cggcaatttc agctttgggt atgccctggt

V F L A T F A A V L G N F S F G Y A L V

181 ctacacatcc cctgtcatcc cagccctgga gcgctccttg gatcctgacc tgcatctgac Y T S P V I P A L E R S L D P D L H L T

241 caaatcccag gcatcctggt ttgggtccgt gttcaccctg ggagcagcgg ccggaggcct K S Q A S W F G S V F T L G A A A G G L 301 gagtgccatg atcctcaacg acctcctggg ccggaagctg agcatcatgt tctcagctgt S A M I L N D L L G R K L S I M F S A V

361 gccgtcggcg gccggctatg cggtcatggc gggtgcgcac ggcctctgga tgctgctgct

P S A A G Y A V M A G A H G L W M L L L

421 cggaaggacg ctgacgggct tcgccggggg gctcacagct gcntgcatcc cggtgtacgt

G R T L T G F A G G L T A A C I P V Y V

481 gtctgagatt gctcccccag gcgttcgtgg ggctctgggg gccacacccc agctcatggc S E I A P P G V R G A L G A T P Q L M A

541 agtgttcgga tccctgtccc tctacgccct tggcctcctg ctgccgtggc gctggctggc V F G S L S L Y A L G L L L P W R W L A 601 tgtggccggg naggcgcctg tgctcatcat gatcctgctg ctcagcttca tgcccaactc

V A G X A P V L I M I L L L S F M P N S

661 gccgcgcttc ctgctctctc ggggcaggga cgaagaggcc ctgcgggcgc tggcctggct

P R F L S R G R D E E L R A L A W L

721 gcgtgggacg gacgtcgatg tccactggga gttcgggcag atccaggaca acgtccggag

R G T D V D V H W E F G Q I Q D N V R R

781 acagagcagc cgagtatcgt gggctgaggc acgggccccc cacgtgtgcc ggcccatcac Q S S R V S W A E A R A P H V C R P I T

841 cgtggccttg ctgatgcgcc tcctgcagca gctgacgggc atcacgccca tcctggtcta

V A L L M R L L Q Q L T G I T P I L V Y 901 cctgcagtcc atcttcgaca gcaccgctgt cctgctgccc cccaaggacg acgcagccat L Q S I F D S T A V L L P P K D D A A I

961 cgttgggncc gtgcggctcc tgtccgtgct gatcgccgcc ctcaccatgg acctcgcagg

V G X V R L L S V L I A A L T M D L A G

1021 ccgcaaggtg ctgctcttcg tctcagcggc catcatgttt gctgccaacc tgactctggg

R K V L L F V S A A I M F A A N L T L G

1081 gctgtacatc cactttggcc ccaggcctct gagccccaac agcactgcgg gcctggaaag L Y I H F G P R P L S P N S T A G L E S 1141 cgagtcctgg ggggacttgg cgcagcccct ggcagcaccc gctggctacc tcaccctggt

E S W G D L A Q P L A A P A G Y L T L V

1201 gcccctgctg gccaccatgc tcttcatcat gggctacgcc gtgggctggg gtcccatcac P L L A T M L F I M G Y A V G W G P I T

1261 ctggctgctc atgtctgagg tcctacccct gcgtgcccgt ggcgtggcct cagggctctg

W L L M S E V L P L R A R G V A S G L C 1321 cgtgctggcc agctggctca ccgccttcgt cctcaccaag tccttcctgc cagtggtgag

V L A S W L T A F V L T K S F L P V V S

1381 caccttcggc ctccaggtgc ctttcctctt cttcgcggcc atctgcctgg tgagcctggt T F G L Q V P F L F F A A I C L V S L V

1441 gttcacaggc tgctgtgtgc ccgagaccaa gggacggtcc ctggagcaga tcgagtcctt F T G C C V P E T K G R S L E Q I E S F

1501 cttccgcacg gggagaaggt ccttcttgcg ctagaagggc g F R T G R R S F L R

TABLE 5B Rat GLUTX3 Nucleotide (SEQ ID NO:13) and Amino Acid (SEQ ID NO:14) Sequences

ggcacgatgc aggagcccct gctaagagcc gagggactgg actatgacac cttccccgag 60

M Q E P L L R A E G L D Y D T F P E gcgcccgcgt cgcctgaaga gaaggcacgg gccggggcct tgcaaaacag aagggtgttc 120 A P A S P E E K A R A G A L Q N R R V F ctggccacct tcgctgccgt gctgggcaat ttcagctttg ggtatgccct ggtctacaca 180 L A T F A A V L G N F S F G Y A L V Y T tctccagtca tccctgcgct gaagcgctct tctgacccag cactacgcct ggacaaaatc 240 S P V I P A L K R S S D P A L R L D K I caggcatcct ggtttgggtc cgtgttcacc ctgggtgccg ccgctggggg cctcagtgct 300 Q A S F G S V F T L G A A A G G L S A atgctactca atgacctctt gggccggaag ctcagcatca tgttttccgc tgtcccctcg 360 M L L N D L L G R K L S I M F S A V P S gccattggct atgcactcat ggctggtgcc cgtggcctct ggatgcttct gctggggagg 420 A I G Y A L M A G A R G L W M L L L G R atgctgacag gctttgccgg gggactcact gctgcctgca tcccggtgta cgtgtctgag 480 L T G F A G G L T A A C I P V Y V S E attgcacccc cgggtgttcg cggggccctg ggggccacgc cgcagctcat ggccgtgttt 540 I A P P G V R ^ G A T Q L M A 1 ggatccctgt ctctctatgc ccttggtctt ctgctgcctt ggcgatggct tgccgtggcc 600

G S L S L Y A L G L L L P W R W L A V A ggggaggggc ctgttctggt catgatcctg ctgcttagct tcatgcccaa ctcgcctcgc 660

G E G P V L V M I L L L S F M P N S P R ttcctactgt ctaagagccg ggatgaggaa gcactgcagg cgctgatctg gctgcgagcg 720

F L L S K S R D E E A L Q A L I W L R A gactctgagg tccactggga gtttgagcag atccaggaca acgtgcggag acagagtagc 780 D S E V H W E F E Q I Q D N V R R Q S S cgagtgtcgt gggcggaggc ctgggagccc cgtgtgtacc ggcctattct cattacagtg 840 R V S W A E A E P R V 1 R P I L I T V ctgatgcgtt ttctgcagca gctgacaggc atcactccca tcctcgtgta cctacagacc 900 L M R F L Q Q L T G I T P I L V Y L Q T atcttcgaca gcacgtccgt ggtgctgccc tcccagcagg atgcagctat agttggtgct 960 I F D S T S V V L P S Q Q D A A I V G A gtgaggctcc tgtctgtgct gattgccgct gtcaccatgg acctggccgg ccgaaaagtc 1020 V R L L S V L I A A V T M D L A G R K V ctgctctatg tgtcagcatc cattatgttt gtcgccaacc tgacgctggg gctgtatgtc 1080 L L Y V S A S I M F V A N L T L G L Y V cagcttgtgc caaggactct gacccccaac agcactgtgg agatcgtgac gcttgggggc 1140 Q L V P R T L T P N S T V E I V T L G G acggagcagc ccccagccgc ggccttcaac tatctcaccc tgatacccct gctggccacc 1200

T E Q P P A A A F N Y L T L I P L L A T atgctcttca ttatgggcta tgccatgggc tgggggccca tcacctggct cctcatgtct 1260

M L F I M G Y A M G W G P I T W L L M S gaggttctgc ccctgcgtgc ccgtggtgtg gcctcagggc tctgcgtgct ggtcagctgg 1320

E V L P L R A R G V A S G L C V L V S W ctcacagcct tcgtcctcac taagtacttc ctgctggcag tgaatgcctt cggcctccag 1380

L T A F V L T K Y F L L A V N A F G L Q gtgcctttct tcttcttctc ggccatctgc ctgctcagcc tgctcttcac aggctgctgt 1440 V P F F F F S A I C L L S L L F T G C C gtgcctgaga ccaggggccg ctcgctggag cagatcgagg ccttcttcca cactcgcagg 1500 V P E T R G R S L E Q I E A F F H T R R atgtccttca ggccctagtc aggggcttgc ctgtaagggg ccaggccatg tgggccaggc 1560 M S F R P X ctgtgcacac ctgcagccgg gagcagcagc acccctgccg tcagccactg cacacttcca 1620 cctsggacag gcagttcacc aactgtgggc tggtgggccc cagcaggcag cccgcagtgc 1680 tgtaatacct cagctgagat ccgcaggggg gcaggcagcc ctgccccaga ctgagcaaag 1740 gctgtaccca agaacaatgc tgttgggacc tccggtctag ttcctcattc ctacaaggaa 1800 cacttcccat gtagggccat gttgaggaca gaaaacaggg atggaggtgg caatgtggca 1860 ttgtacaagg acattgtcac ttccttctga tcaactggcc agggggagga cagggtcctg 1920 taccctcaag ggtctgggta ccttggggag cactggaccc agtccaacct tggatacctc 1980 tagtctacag actgttcact gtttttcaaa a 2011

TABLE 5C

Sequence alignment of human and rat GLUTX3 protein sequences and Majority GLUTX3 Sequence (SEQ ID NO:17)

TMl hX3 MQEPLLGAEGPDYDTFPEKPPPSPGDRARVGTLQNKRVFLATFAAVLGNFSFGYALVYTS rX3 MQEPLLRAEGLDYDTFPEAP-ASPEEKARAGALQNRRVFLATFAAVLGNFSFGYALVYTS

_**_**** * _{* * ***}***_{* * * *} .. * _* *._***._************************ Maj oπty MQEPLLgAEGpDYDTFPEkPpASPgdrARvGtLQNkRVFLATFAAVLGNFSFGYALVYTS TM2 TM3 hX3 PVIPALERSLDPDLHLTKSQASWFGSVFTLGAAAGGLSAMILNDLLGRKLSIMFSAVPSA rX3 PVIPALKRSSDPALRLDKIQASWFGSVFTLGAAAGGLSAMLLNDLLGRKLSIMFSAVPSA _{********* * * *} . _{* * *********************}._{*******************}

Majority PVIPALeRSlDPdLhLtKsQASWFGSVFTLGAAAGGLSAMiLNDLLGRKLSIMFSAVPSA TM4 TM5 hX3 AGYAVMAGAHGLWMLLLGRTLTGFAGGLTAACIPVYVSEIAPPGVRGALGATPQLMAVFG rX3 IGYALMAGARGLWMLLLGRMLTGFAGGLTAACIPVYVSEIAPPGVRGALGATPQLMAVFG

_{* * *} . _{* * * *} * _{********* ****************************************}

Majority aGYAvMAGAhGLWMLLLGRtLTGFAGGLTAACIPVYVSEIAPPGVRGALGATPQLMAVFG

TM6 hX3 SLSLYALGLLLP RWLAVAGXAPVLIMILLLSFMPNSPRFLLSRGRDEEALRALAWLRGT rX3 SLSLYALCLLLPWRWLAVAGEGPVLVMILLLSFMPNSPRFLLSKSRDEEAL ALIWLR-A

_{******************** ***}*_{*****************}* _*******_{** * * *}

Majority SLSLYALGLLLPWRWLAVAGXaPVLiMILLLSFMPNSPRFLLSrgRDEEALrALaWLRgt TM7 hX3 DVDVHWEFGQIQDNVRRQSSRVSWAEARAPHVCRPITVALLMRLLQQLTGI PILVYLQS rX3 DSEVHWEFEQIQDNVRRQSSRVSWAEAWEPRVYRPILITVLMRFLQQLTGITPILVYLQT

* ._***_** *_*****_************ * . * * * _* ...***._*******_****_***_*.

Ma ority DvdVHWEFgQIQDNVRRQSSRVSWAEAraPhVcRPItvalLMRlLQQLTGITPILVYLQs TM8 TM9 hX3 IFDSTAVLLPPKDDAAIVGXVRLLSVLIAALTMDLAGRKVLLFVSAAIMFAANLTLGLYI rX3 IFDSTSVVLPSQQDAAIVGAVRLLSVLIAAVTMDLAGRKVLLYVSASIMFVANLTLGLYV

_{********** * ******* **********}*_************_****_{*** ********}* Majority IFDSTaVlLPPkdDAAIVGaVRLLSVLIAAlTMDLAGRKVLLfVSAalMFaANLTLGLYi

+ TM10 hX3 HFGPRPLSPNSTAGLESESWGDLAQPLAAPAGYLTLVPLLATMLFIMGYAVGWGPITWLL rX3 QLVPRTLTPNSTVEIVT—LGGTEQPPAAAFNYLTLIPLLATMLFIMGYAMGWGPITWLL

_{* * *}*_**** . . _{* * * * * ****}*_{*************}*_*********

Majoπty hfgPRrLsPNSTagleseswGdlaQPlAApagYLTLvPLLATMLFIMGYAvGWGPITWLL TM11 TM12 hX3 MSEVLPLRARGVASGLCVLASWLTAFVLTKSFLPVVSTFGLQVPFLFFAAICLVSLVFTG rrXX33 MSEVLPLRARGVASGLCVLVSWLTAFVLTKϊFLLAVNAFGLQVPFFFFSAICLLSLLFTG

Maj ority MSEVLPLRARGVASGLCVLaSWLTAFVLTKsFLpvVstFGLQVPFlFFaAICLvSLvFTG

hhXXJJ

rX3 CCVPETRGRSLEQIEAFFHTRRMSFRP

_{***************}._**._{* * * *}

Majority CCVPETkGRSLEQIEsFFrTgRrSFlr

The GLUTX family members were aligned using ClustalX and ClustalW software analyses. The alignment of human GLUTXl, GLUTX2 and GLUTX3 protein sequences and the human GLUTX consensus sequence (SEQ ID NO: 18) are shown in Tables 6E and 6A, respectively. The alignment of rat GLUTXl, GLUTX2 and GLUTX3 protein sequences is shown in FIG.3, with alternative alignments indicated in Tables 6C and 6F and described below. The rat GLUTX consensus sequence from FIG.3 (SEQ ID NO: 19) is shown in Table 6B. Underlined sequences in the various tables depicting consensus sequences, i.e., Tables 6A, 6B and 6D, depict residues that are conserved between the GLUTX family of sequences but are not conserved between the GLUTX family and the GLUTl -5 family of proteins. Conserved regions between GLUTXl and the GLUT family of sequences are indicated by dark and shaded residues in FIG. 1 and described more fully in the DETAILED DESCRIPTION above. GLUTX2 and GLUTX3 homologies to the GLUT family of sequences can easily be determined by one skilled in the art by the juxtaposing of the alignments of GLUTX 1-3 in the tables below with the sequence of GLUTXl, and hence with the other GLUT family member, in FIG. 1.

Table 6C represents an alternative alignment of GLUTX 1 -3 residues around the single putative glycosylation site, as compared to the alignment in FIG. 3. In Table 6C, the putative glycosylated N residue, indicated by (+), is aligned between all three polypeptides. The modified alignment creates an alternative rat GLUTX consensus sequence (SEQ ID NO:20) for the sunounding region, as shown in Table 6D. An alignment of human GLUTXl -3 using ClustalW (Table 6E) was used to generate a "Majority" human GLUTX sequence (SEQ ID NO:21). Alignments rat GLUTX proteins were determined with ClustalW version 1.7 software (Table 6F) using default parameters, and with ClustalX software (FIG. 2) as described above. The alternative alignment of rat GLUTXl -3 using ClustalW (Table 6F) was used to generate a "Majority" rat GLUTX sequence (SEQ ID NO:22) depicting the most common residues at a given position in the alignment. An "x" at any given position denotes that all residues at that position are different in each of the GLUTX sequences in the alignment. A residue designated by an "x" may be strongly conserved, weakly conserved, or nonconserved. The degree of conservation will be indicated in its respective table.

In the consensus sequences for human and rat GLUTX, shown in Tables 6A, 6B and 6D and provided as SEQ ID NOs: 18, 19 and 20, upper case letters denote a fully conserved single residue that appears in the same position in all three GLUTX sequences. Lower case letters denote conserved residues that appear in the same position in two of the three GLUTX sequences used in the alignment. Shaded regions in the consensus sequences indicate residues that appear only in GLUTX2 (fg-), only in GLUTXl and GLUTX3 but not GLUTX2 (Q), and only in GLUTX2 and GLUTX3 but not GLUTXl (-X-). In alternative embodiments, polypeptides representing GLUTX consensus sequence may or may not contain the residues in one or more of the regions indicated by shading. For example, all or some of the GLUTX2 specific residues may be omitted from a consensus polypeptide. Alternatively, all or some of the residues specific to GLUTX2 and GLUTX3, but not in GLUTXl, may be omitted from a consensus polypeptide Nucleic acids encoding the shaded residues may likewise be omitted in alternative embodiment of GLUTX consensus nucleotide sequences.

TABLE 6A Consensus Human GLUTX Amino Acid (SEQ ID NO:18) Sequence from FIG. 3A

KEY: GLUTX2 specific = hx-

GLUTX 1+3 only = E-BB

GLUTX 2+3 only = -x-

^~* = variable number of N-ter residues after the M translation start

- = spacers for consensus residues indicating variable

Upper case = identical residues

Lower case = conserved strong ana weak residues

Mqe.r,.rr--pEpdaasa LL-A-gp pggs a-R--Rr Q ς^ 60 VflaafaaaLG-fsFFyalgy-Spaιp-L-R-1-P Lα aswfgsv-t IgAAagq 120 l-gcj-ln —GrHs.U-svpf-^C-ay-aaB wmlL-CrlltC^a-G-as PVY 180 sEiap ^p-vRG-Lα

-"^p-- n-ll 240

--ErιPesPRlL_^--gr-qeA-ruL—lrG wE I-α>- e—- --Aj™^ 300

--lr-P rD-ivg--l--fQQLsGin-in-Y--tIf £ - a-vvg— 360

Ξ^^-^^^" ---^.-r^.-^^- s-s-pv-aqp—a-a -c,^--^---^.--~ 480

^gg^π^g^_₁__w__all Lf_l-gfAvGwGPipWllmSEi-PL-argva-g-cyl-nW 540

1-aflvtk-Fl e-l--ygaF-l-aafc -sllFt--CvPEtKGι--Leqles-F R 600

636

TABLE 6B Consensus Rat GLUTX Amino Acid (SEQ ID NO:19) Sequence from FIG. 3B

KEY: GLUTX2 specific = ψ$E- GLUTX 1 + 3 only = BB GLUTX 2+3 only = -x- * = variable numoer of N-:er residues alter tn« ¥ translation start

- = spacers for consensus residues indicating variable Upper case = identical residues

_^ower ca s k - conserved stroⁿα and wee residues

_*

1 M-pE--dp

50 aaaLG- f sFGyalgysSpaιp-Lr ^^5-3 rιL^.-H^AsWr 9^_vvtC;¹5 100 AAAgqql-qg-Lnd-lGRklsιll-tvp-- Gf a viaaAr-vwmLLgGRI 150 HGla-Gvasl-iPVYisEiapPavRG-Lgs — qLmvv-G-l-ayvlgj§

200 EwlI-BwRwlaylg-vP-llmILlm-fmPesPRfLltk-q-qeAm-aL

250 -flrg-sev-wEfe-1 vehq s-A|§ jjjjJgfml--P-vhrpl:ι.ιq

300 1-1-vfQQLsGιn-ImfY-nTIfe-t-v-d-fgjs a-ivg-iqvlf tl

350 vaalimdraGRklLlyElsgsim- smlalGEly-ql pr-^S-qP

4 0 sEg^Bg^5g555.^S^S5Bg5nss-vvEltlvpι-BBqepA o0 fcasaSS_tMiSSS_aS?*⁰' ^vn~ ^ISS-S^"^ wl a 11 ammL f img f AvGwG P lpW

500 llmSEιfPLharBBatGivCvl|vnWl-aflvtk-Fl — me-1— yqaFf

550 lfaafcιIslLFt--cvPETkGrtLEqlea-Fe-R — s BBB5SB

TABLE 6C Partial Alternative Alignment for Consensus Rat GLUTX Amino Acid Sequences in

FIG.3

+ rGLUTxl_pep 346 S GPS NSSHVG—LLV rGLUTx3_pep 346 RT LTP NSTVEIV-TLG rGLUTx2_pep 346 RVTFRPTAPSGQNATCTEYSYCNECMLDPDCGFCYKINSSAVIDSSCV consensus 421 r gPS NSs-vι--tlv

TABLE 6D Alternative Consensus Rat GLUTX Amino Acid (SEQ ID NO:20) Sequence

KEY: GLUTX2 specific = pgj

GLUTX 1+3 only = -B8

GLUTX 2+3 only = -x-

* = variable number of N-ter residues after the M translation start

- = spacers for consensus residues indicating variable

Upper case = identical residues

Lower case = conserved strong and weak residues

1 M-pE— dp llasp-ara-qGa---MRREBEBΞKgvflAtf

100 AAAJggl-gg-Lnd-lGRklsιll-tvp--ιGfavιaaAr-vwmLLgGRl

150 ltGla-Gvasl-ιPVYιsEιapPavRG-Lgs--qLmvv-G-l-ayvlg||J

20 J Eawll-E: Rwιaylg-vP- lmlLlm-fmPesPRf ltk-q-qeAm-aL

250 -flrg-sev-wEfe-1 vehq .s-AHMMlBml — P-vhrplng

300 ι-1-vfQQLsGιn-ImfY-nTIfe-t-v-d-jfffs a-ivg-iqvlf tl

350 vaalimdraGRklLlyBlsgsim-vsmlalGgly-qltpr-^Ki-σP

400 S^^^^^^^g^^^^^g^S5NSs-vιEtl p -^glαepA

500 llmSEifPLharBEatGivCylιBS.v.nWl-aflvtk-Fl — e-1—ygaFf

550 lfaafcilslLFt—cvPETkGrtLEqlea-Fe-R- 600 j^^gSSSS TABLE 6E

Sequence alignment of human GLUTXl, GLUTX2 and GLUTX3 polypeptide sequences and Majority human GLUTX Sequence (SEQ ID NO:21)

hX3 MQEP LLGAEGPDYDTFPEKPPPSPGDRA RVGTLQNKR— hXl MTPEDP EETQPLL GP PGGS APRG-RR hX2 MGERRRKQPEPDAASAAGECSLLAAAESSTSLQSAGAGGGGVGDLERAARRQFQQDETPA * * * * * * .

Maj ority MgerrrxxpEpdaasaxxxxxLLxAxgpxxxxxxxxpggsxxxxaxRxaRrxxxQxxxpa hX3 -VFLATFAAVLGNFSFGYALVYTSPVIPALERSLDPDLHLTKSQAS FGSVFTLGAAAGG hXl -VFLAAFAAALGPLSFGFALGYSSPAIPSLQRAAPPAPRLDDAAASWFGAVVTLGAAAGG hX2 FVYVVAVFSALGGFLFGYDTGVVSGAMLLLKRQLS LDALWQELLVSSTVGAAAVSA

Majority fVflaafaaaLGxfsFFyalgyxSpaipxLxRxlxPxxxLdxxxaswfgsvxt IgAAagg hX3 LSAMILNDLLGRKLSIMFSAVPSAAGYAVMAGAHGL MLLLGRTLTGFAGGLTAACIPVY hXl VLGG LVDRAGRKLSLLLCSVPFVAGFAVITAAQDV MLLGGRLLTGLACGVASLVAPVY hX2 LAGGALNGVFGRRAAILLASALFTAGSAVLAAANNKETLLAGRLVVGLGIGIASMTVPVY

* * _* * * * * . . * . _* * * * . * . * . . . * * * Majority lxggxLndxxGrklsillxsvpfxAGxAVxaaAxxxwmLLxGrlltGlaxGxasxxxPVY hX3 VSEIAPPGVRGALGATPQLMAVFGSLSLYALG LLLP R LAVAGXAPVLIMILL hXl ISEIAYPAVRGLLGSCVQLMVVVGILLAYLAG VLE RWLAVLGCVPPSLMLLL hX2 IAEVSPPNLRGRLVTINTLFITGGQFFASVVDGAFSYLQKDG RYMLGLAAVPAVIQFFG

Majority isEiapPxvRGxLgxxxqlmxvxGxxxayxxggafsylxxlx rwlavlgxvPxximxll hX3 LSFMPNSPRFLLSRGRDEEALRALA LRGTDVDVH EFGQIQDNVRRQSSRVS A hXl MCFMPETPRFLLTQHRRQEAMAALRFLWGSEQ—G E DPPIGAEQSFHLA hX2 FLFLPESPR LIQKGQTQKARRILSQMRGNQT-IDEEYDSIKNNIEEEEKEVGSAGPVIC

Majority xxFmPesPRfLlxxgrxqeAxraLxxlrGxxxdxxwExxxIxdnxxxxexxvxxAgpvic hX3 -EARAPHVCRPITVALLMRLLQQLTGITPILVYLQSIFDSTAVLLP PKDDAAIVGXV hXl -LLRQPGIYKPFIIGVSLMAFQQLSGVNAVMFYAETIFEEAKFKDS SLASVVVGVI hX2 RMLSYPPTRRALIVGCGLQMFQQLSGINTIMYYSATILQMSGVEDDRLA-IWLASVTAFT

. _{* * *} . _*

Majority rxlr PxxxrpxivgxxIxxfQQLsGinximxYxxt Ifxxxxvxxxrlapxxxaxvvgxx hX3 RLLSVLIAALTMDLAGRKVLLFVSAAIMFAANLTLGLYIHFGPRP LSPNS-- hXl QVLFTAVAALIMDRAGRRLLLVLSGVVMVFSTSAFGAYFKLTQG GPG hX2 NFIFTLVGV LVEKVGRRKLTFGSLAGTTVALIILALGFVLSAQVSPRITFKPIAPSGQN

. . * _* . _* * . . . . *

Majority xxlftlvaalx dxaGRrxLlfxSxaxmxxaxxxlglyfxlxxxxspritfkpxxPxxqn hX3 TAGLESESWGDLAQPLAAPAGY hXl NSSHVAISAPVSAQPVDASVG hX2 ATCTRYSYCNECMLDPDCGFCYKMNKSTVIDSSCVPVNKASTNEAA GRCENETKFKTED Majority atctrysycnecmldpdcgfcykmnkxxxxxsxsxpvxaqpxxaxagxrcemetlflted hX3 LTLVPLLATMLFIMGYAVGWGPITWLLMSEVLPLRARGVASGLCVLAS hXl LA LAVGNMCLFIAGFAVG GPIPWLLMSEIFPLHVKGVATGICVLTN hX2 IF AYNFCPTPYS TALLGLILYLVFFAPGMGPMPWTVNSEIYPLWARSTGNACSSGINW

^ . . *.. .* * **. * . _**. ** . *

Ma] ority ifwaynfcptplxwxallxxxLfixgfAvGwGPip llmSEixPLxargvaxgxcvlxn h 3 LTAFVLTKSFLPVVSTFGLQVPFLFFAAICLVSLVFTGCCVPETKGRSLEQIESFFRTGR hXl LMAFLVTKEFSSLMEVLRPYGAF LASAFCIFSVLFTLFCVPEIKGKTLEQITAHFEG-R 0 hX2 IFNVLVSLTFLHTAEYLTYYGAFFLYAGFAAVGLLFIYGCLPETKGKKLEEIESLFDN-R

... * . * . . . .. * *.*_{* *}*. **._* . * *

Majority Ixaflvt kxFlxxxexlxxygaFxlxaafcixs11FtxxCvPEtKGkxLeqlesxFxxgR hX3 RSFLR 5 h l hX2 LCTCGTSDSDEGRYIEYIRVKGSNYHLSDNDASDVE Ma] ority xxxxxtsdsdegryiey rvkgsnyhlsdndasdve

TABLE 6F 0 Alternative Sequence alignment of rat GLUTXl, GLUTX2 and GLUTX3 protein sequences and Majority rat GLUTX Sequence (SEQ ID NO:22) glutx3rat MQEPLLRAEGLDYDTFPEAPASPEEKARAGALQN RRVFLATFAAVL glutxlrat MSPEDPQETQPLLRSPGARAPGGRRVFLATFAAAL 5 glutx2rat MGERRRRQPEPGAPGGERSLLAAESAASLQGAELERAARRQFQRDETPAFVYAAAAFSAL

_* . *. _*. . *

Ma] ority mgerrrrqpepxxxxxxRxxxxxxxxxpexpaexexxaRxxxxrxxxxrrVflAt faaaL glut 3rat GNFSFGYALVYTSPVIPALKRSSDPALRLDKIQAS FGSVFTLGAAAGGLSAMLLNDLLG 0 glutxlrat GPLSFGFALGYSSPAIPSLRRTAPPALRLGDTAAS FGA VTLGAAAGGVLGGWLLDRAG glutx2rat GGFLFGYDTGVVSGAMLLLRR QMRLGAM QELLVSGAVGAAAVAALAGGALNGALG

Ma] ority GxfsFGyalgyxSpxipxLrRxxxxalRLgxxxaswfgsvxtIgAAagglxggxLndxlG 5 glutx3rat RKLSIMFSAVPSAIGYALMAGARGLWMLLLGRMLTGFAGGLTAACI PVYVSEIAPPGVRG glutxlrat RKLSLLLCTVPFVTGFAVITAARDVWMLLGGRLLTGLACGVASLVAPVYISEIAYPAVRG glutx2rat RRSAILLASALCTVGSAVLAAAANKETLLAGRLVVGLGIGIASMTVPVYIAEVSPPNLRG _{* * *}... _{* *}* _**.. _*. * ... _***.._*.. * .*_*

Ma] ority RklsillxxvpxxxGxAvxaaarxxwmLLxGRlluGIaxGxasxxxPVYisSiapPxvRG 0 glutx3rat ALGATPQLMAVFGSLSLYALG LLLPWR LAVAGEGPVLVMILLLSFMPNSPRFL glutxlrat LLGSCVQLMVVTGILLAYVAG VLEWR LAVLGCVPPTLMLLLMCYMPETPRFL glutx2rat RLVTINTLFITGGQFFASVVDGAFSYLQKDGWRYMLGLAAIPAVIQFLGFLFLPESPR L

. _* .. * _* . 5 Majority xLgxxxqLmxvxGxlxayvxggafsylxxlx RwlavlgxxPxxxmlLlxxfmPesPRfL glutx3rat LSKSRDEEALQALI LRADSEVH EFEQIQDNVRRQSS RVS AEA EPRVYRPI glutxlrat LTQHQYQEAMAALRFLWG-SEEGWE EPPVGAEHQ GFQLAMLRRPGVHKPL glutx2rat IQKGQTQKARRILSQMRGNQTIDEEYDSIRNSIEEEEKEASAAGPIICRMLSYPPTRRAL 0

Ma] ority lxkxqxqeAxxaLxxlrgxsexxwExxxixxxvxxxxxeasaagxxxxamlxxPxxxrpl glutx3rat LITVLMRFLQQLTGITPILVYLQTIFDSTSVVLP—SQQDAAIVGAVRLLSVLIAAVTMD glutxlrat IIGICLMVFQQLSGVNAIMFYANTIFEEAKFKD SSLASVTVGIIQVLFTAVAALIMD 5 glutx2rat AVGCGLQMFQQLSGINTIMYYSATILQMSGVEDDRLAI LASITAFTNFIFTLVGVWLVE

Ma] ority xigxxlxxfQQLsGmxImxYxxTIfxxxxxxdxrlsxxxaxivgxxxxlftlvaaxxmd glutx3rat LAGRKVLLYVSASIMFVANLTLGLYVQLVPRT LTPNST glutxlrat RAGRKLLLALSGVIMVFSMSAFGTYFKLTQS GPSNS glutx2rat KVGRRKLTFGSLAGTTVALTILALGFLLSAQVSPRVTFRPTAPSGQNATCTEYSYCNECM

_{* *} . _{* *} . . _* *

Ma] ority xaGRkxLlxxSxximxvaxxxxgxyfxLxxxxsprvtfrpxxPsxxnatcteysycnecm glut 3rat VEIVTLGGTEQPPAAAFNY LT glutxlrat SHVGLLVPISAEPADVHLG LA glutx2rat LDPDCCFCYKINSSAVIDSSCVPVNKASTNEAA GRCENETKFKAEDVH AYSFCPTPYS

*

Ma] ority ldpdcgfcykxxxxxlxxxsxxPaxxxxxneaawgrcenetkfkaedvhwaysfcptplx glutx3rat LIPLLATMLFIMGYAMGWGPIT LLMSEVLPLRARGVASGLCVLVS LTAFVLTKYFLLA glutxlrat LAVGSMCLFIAGFAVGWGPIP LLMSEIFPLHIKGVATGVCVLTNWFMAFLVTKEFNSI glutx2rat WTALVGLVLϊLVFFAPGMGPMPWTVNSEIYPL ARSTGNACSAGINWI FNVLVSLTFLET

_* . . . * * _{* *} . * . * _* . * * . _* . ... *

Ma] ority wlalxxxxLfixgfAxGwGPip llmSEixPLxargvaxgxcvlxnWxxaflvtkxFlxx glutx3rat VNAFGLQVPFFFFSAICLLSLLFTGCCVPETRGRSLEQIEAFFHTRRMSFRP glutxlrat MEILRPYGAF LTAAFCILSVLFTLTFVPETKGRTLEQITAHFEGR glutx2rat AEYLTYYGAFFLYAGFAAVGLLFVYGCLPETKGKKLEEIESLFDHRLCTCGTADSDEGRY

_* . . . . . . * _* . _{* * *} . _* . * * . * . _{* *}

Ma] ority xexlxxygaFfIxaafcilslLFtxxcvPETkGrxLEqleaxFxxRxxxxxxadsdegr^ glutx3rat glutxlrat glutx2rat IEYIRVKGSNYHLSDNDASDVE

Majority leyirvkgsnynlsdndasdve

Example 2. Northern Blot Analysis

GLUTXl tissue distribution was assessed by Northern blot analysis of adult rat tissues total RNA. The strongest expression was seen in testis, with moderate expression in the cerebellum, brain stem, hippocampus, hypothalamus, adrenal gland, liver, spleen, brown adipose tissue, and lung. A low level of expression was detected in white adipose tissue, muscle, kidney, tongue and was barely detectable in intestine and stomach. No GLUTXl expression was detected in thyroid.

Transient expression of both GLUTX2 and GLUTX3 transporters in HEK293 cells and immunofluorescence microscopic detection revealed that both GLUTX2 and GLUTX3 were located in intracellular compartment. For GLUTX2, at least, surface expression could be induced by mutating a dileucine internalization motif present the amino-terminal tail of the transporter and a tyrosine-based motif present in the carboxy-terininal cytoplasmic tail. GLUTX3 also possesses dileucine and tyrosine-based internalization motifs.

The tissue localization of GLUTX2 and GLUTX3 almost exclusively in the brain, their mtracellular localization and the presence of dileucine motifs suggest the surface expression of these molecules may be triggered by some as yet unknown stimuli which may be coupled with increased brain activity. It has indeed been shown that stimulation of activity of different brain regions is associated by increased glucose metabolism, that ischemia leads to increase glucose utilization and that diseases of the central nervous system may be associated with impaired stimulation of glucose uptake by specific brain areas

Methods: Total RNA was isolated as described. See, e.g., Chomczynski and Sacchi 1987 Anal Biochem. 162: 156-159. Northern blot analysis was with 10 μg of total RNA, and detection was with a 1.2-kilobaseNotI-i?g II fragment from the coding sequence of GLUTXl radioactively labeled by random priming.

Example 3. GLUTX Protein Analysis

GLUTXl synthetic mRNA was in vitro translated in reticulocyte lysate in the presence or absence of canine pancreas microsomal membranes. Gel electrophoresis results showed that the primary translation product migrated as a 35-kDa band, a higher electrophoretic mobility as compared with the predicted molecular mass of 51 kDa. In the presence of microsomal membranes, a part of the 35-kDa band was converted to a higher molecular mass of 37 kDa. This was due to /V-glycosylation of the protein as demonstrated by the susceptibility of this band to digestion by both endoglycosaminidase H and PNGaseF. This modification probably takes place at the unique A/-glycosylation site present in the exoplasmic loop between TM9 and TM10.

An in vitro translation of GLUTXl cRNA using rabbit reticulocyte lysate in the presence (+MM) or absence (MM) of canine pancreatic microsomal membranes is described in the Method section below. In the reaction without microsomal membranes, only one band of approximately 35 kDa is present. An additional band of approximately 37 kDa is present in the reaction with microsomal membranes, indicating that this is the glycosylated form of GLUTXl . This was confirmed by sensitivity of the 37-kDa band to EndoHf or PNGaseF. B, Western blot of membrane proteins from HEK293T cells transiently transfected with wild- type GLUTXl and control 293T cells. Membrane protein preparations from transfected cells were incubated at 37 °C for 2 h in the presence or absence of PNGaseF as described under "Materials and Methods." Each lane contains 20 μg of protein. Immunodetection was with the affinity purified GLUTXl (203-257) antibody as described below.

Methods: In vitro transcription was performed from linearized pSD5-GLUTXl vector using SP6 RNA polymerase (Promega). cRNA was in vitro translated in rabbit reticulocyte lysate in the presence or absence of canine microsomal membranes (Promega) and [³⁵S]methionine (NEN Life Science Products). Products were separate on 10% polyacrylamide gels and detected by autoradiography. For Western blotting, GLUTXl was transiently transfected in HEK293T cells, and cell membranes were prepared and analyzed using specific antibodies following previously published procedures See, e g , Jordan et al 1996 Nucleic Acids Res 24 596-601 , Widmann et al 1995 Biochem J 310 203-214 Endoglycosidase H and PNGaseF (New England Biolabs) digestions were performed according to the manufacturer's protocol

Immunofluorescence microscopic detection of GLUTXl or GLUTX l(LL-AA) was performed following transient transfection of HEK293T cells as previously described using 10 μg/ml GLUTXl affinity-purified antibody and CY3 -conjugated goat anti-rabbit antibody (Jackson ImmunoResearch) See, e g , Gilboe et al 1912 Anal Biochem 47 20-27

Example 4. Functional Characterization of GLUTX in Xenopus Oocytes

To determine whether GLUTXl was a functional glucose transporter, synthetic mRNAs were transcribed in vitto from the full-length rat cDNA and injected in Xenopus oocytes, and 2-DOG uptake was measured 3 days later As shown in FIG 5, 2-DOG uptake by oocytes injected with the wild-type GLUTXl mRNA was not significant We suspected that the lack of transport activity was due to the dileucine motif present at the amino-terminal end of the protein, which could serve as an internalization signal preventing sufficient surface expression of GLUTXl We therefore mutated these two leucines into alanines and injected oocytes with the corresponding mutant mRNA Transport activity by these injected oocytes was now strongly stimulated (FIG 5 Panel A) FIG 5 Panel B shows that a 100-fold excess of D-glucose could completely block radioactive 2-DOG uptake, whereas L-glucose was not a competitor D-Fructose and D- galactose could also inhibit glucose uptake, although with a reduced efficacy as compared with D-glucose Uptake could also be blocked by cytochalasin B, a specific inhibitor of all the mammalian glucose transporter isoforms Finally, the affinity of the transporter for glucose was determined, as shown in FIG 5 Panel C Michaehs-Menten analysis of the fitted curve indicates a K„, for 2-DOG of approximately 2 4 mM

Analysis of GLUTX2 is shown in FIG 6 Methods are discussed below Methods Stage V-VI oocytes were injected with 25 ng of RNA prepared from GLUTXl and GLUTXl(LL-AA) cDNA cloned into pSD5, as described See, e g , Geermg et al 1996 J Cell Biol 133 1193-1204 2-Deoxy-D-glucose (2-DOG) uptake assays were performed 3 days following injection with groups of 8-10 oocytes incubated in the presence of 2 mM 2-DOG and 20 μCi of [l,2-³H]deoxy-D-glucose (Moravek Biochemicals) for 45 mm 2-DOG uptake was previously confirmed to be linear with time throughout this peπod Oocytes were then washed with ice-cold solution containing 1 mM HgCl₂. Individual oocytes were dissolved in 2% SDS, mixed with scintillation fluid, and counted. For determination of the Michaelis-Menten constant, uptake was for 15 min at the indicated 2-DOG concentration. In FIG. 5, panel A, 2-DOG uptake was measured in stage V-VI Xenopus oocytes injected with 25 ng of GLUTXl wild-type (WT) RNA and GLUTXl(LL-AA) RNA compared with noninjected control oocytes. The concentration of 2-DOG was 2 mM. Each bar represents the average for 10 oocytes. In FIG. 5, panel B, all conditions used 2-DOG concentration of 2 mM. 8-10 oocytes per condition were incubated with 250 mM D-glucose, 250 mM L-glucose, 250 mM D-galactose, 250 mM D-fructose, or 50 μM cytochalasin B. Results are expressed as percentages of average 2-DOG uptake in nontreated oocytes (top bar). The results shown are an average of two experiments performed with two different batches of oocytes. In FIG. 5, panel C, 2-DOG uptake was measured at varying concentrations from 0.07 to 10 mM. Each point represents the average uptake from 8 to 10 oocytes. Fig 6 shows the dose curve for uptake of myo-inositol in oocytes injected with 25 ng of GlutX2(RRR-AAA) RNA, fitted using the Michaelis-Menten equation. Myo-inositol uptake was measured at varying concentration from 2.5 microM to 5 mM. Each point represents the average uptake from 8 to 10 oocytes.

Example 5. GLUTX Antibodies

To further characterize the protein, antibodies were raised against either the middle intracellular loop of the transporter or against its carboxyl-terminal tail. FIG. 4 shows the rat GLUTX amino acid sequence with position of the transmembrane domains, N-linked glycosylation site, LL internalization motif and the sequence of the proteins that were used for generating antibodies. Boxes indicate the putative TM domains. The underlined sequences are the sequences used to construct fusion proteins with GST for antibody production in rabbits. The LL motif in the amino-terminal domain, when mutated to AA (i.e., Ala-Ala), allows surface expression of the GLUTX transporter protein. This GLUTX(LL) mutant was used to analyze expression in oocytes, above, and measurements of hexose uptake, above.

The antibodies were characterized by Western blot using membrane fractions prepared from HEK293T cells transfected with GLUTXl . No reactive bands were detected in mock- transfected cells, whereas two prominent bands were detected in GLUTXl -expressing cells: a laddering band extending from approximately 37 to 50 kDa, and a band with a molecularmass of greater than 70 kDa. The same two bands were seen using either the middle loop or the carboxyl-terminal antibodies. After treatment of the membranes with PNGaseF, the 37-50-kDa band shifted toward a well defined band centered at approximately 35 kDa The migration of the upper band was, however, only slightly affected This band may represent nonspecific dimer aggregates of the lower band, because it is also sometimes visible in the reticulocyte lysates, and its intensity relative to the 37-50-kDa band depends in part on the cell lysis conditions, in particular on the addition of reducing agents

To determine the cellular localization of GLUTXl , its cDNA was transiently expressed in HEK293T fibroblasts, and lmmunostaining was performed using the affinity-purified antibody directed against the cytoplasmic loop of GLUTXl GLUTXl showed a strong mtracellular staining but no surface expression Because mutation of the amino-terminal tail dileucine motif to alamnes leads to detection of transport activity when the corresponding mRNA was injected into oocytes, we expected that the same mutant would be expressed at the cell surface Results showed that most of the GLUTX l(LL-AA) is expressed on plasma membrane of transfected HEK293T cells This therefore confirms the importance of this signal on the mtracellular retention of GLUTXl GLUTXl immunolocahzation was analyzed by in situ hybridization in the adrenal medulla of the rat Little to no GLUTXl staining was found in the rat adrenal cortex In the adrenal medulla, cytoplasmic structures, which stained for GLUTXl, localized to what appear to be nerve endings innervating chromaffm cells Excitation of these nerves triggers catecholarmnes release from the chromaffm cells In addition, GLUTXl was innumolocahzed to the pituitary GLUTXl colocalization with vasopressm but not oxytocin in these cells GLUT2 was shown by immunolocahzation to be expressed in nerves and ghal cells of the brain, including ghal cells, ghal cells in the arcuate nucleus, and pyramidal cells

Methods Antibodies were raised against fusion proteins consisting of glutathione .S-transferase and either the middle loop (amino acids 203-257) or the carboxyl-terminal tail (amino acids 459-478) of rat GLUTXl Preparation of fusion proteins by PCR and immunization of rabbits were as described previously See, e g , Widmann et al 1995 Biochem J 310 203-214 Affinity purification of the antibodies was on immobilized fusion proteins consisting of maltose binding protein, and the same regions of rat GLUTXl were used for immunization See, e g , Widmann et al 1995 Biochem J 310 203-214

Example 6. Therapeutic uses of GLUTX compositions

The present invention may have direct bearing on the molecular causes of activity- dependent increase m glucose metabolism by bram neurons, in the normal situation, in ischemia and in the development of neurological pathologies, including neurodegenerative diseases. Therefore, GLUTX polypeptides, nucleic acids and antibodies, as well as fragments, derivatives homologs and analogs thereof, can be used in the diagnosis of these diseases if genetic mutations can be identified as causes of these diseases.

In addition, endogenous GLUTX polypeptides can be used as a drug target by which small molecules or peptides can induce the surface expression of these transporter to stimulate glucose metabolism, either in the normal or diseased state.

GLUTX compositions can be used in gene therapy of diseases of the central nervous system. For instance, they can be engineered in lentiviral vectors that represent the tool of choice for transfer of genes into neurons. GLUTX2 and/or GLUT3 can thus be reexpressed at a normal level or overexpressed to facilitate glucose metabolism by damaged cells.

EQUIVALENTS

From the foregoing detailed description of the specific embodiments of the invention, it should be apparent that particular novel compositions and methods involving nucleic acids, polypeptides, antibodies, detection and treatment have been described. Although these particular embodiments have been disclosed herein in detail, this has been done by way of example for purposes of illustration only, and is not intended to be limiting with respect to the scope of the appended claims that follow. In particular, it is contemplated by the inventors that various substitutions, alterations, and modifications may be made as a matter of routine for a person of ordinary skill in the art to the invention without departing from the spirit and scope of the invention as defined by the claims. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims.

Claims

What is claimed is:

1 An isolated nucleic acid molecule encoding GLUTX, said molecule comprising a nucleotide sequence encoding a polypeptide having a sequence that is at least 85% identical to SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, or the complement of said nucleic acid molecule

2 The nucleic acid molecule of claim 1 , wherein said nucleotide sequence encodes a polypeptide of SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, or the complement of said nucleic acid molecule

3 The nucleic acid molecule of claim 1, said molecule encoding the human GLUTX of SEQ ID NO 1 , 3, 5, 7, 9, 1 1 or 13, or the complement of said nucleic acid molecule

4 The isolated nucleic acid molecule of claim 1, said molecule hybridizing under stringent conditions to a nucleic acid sequence complementary to a nucleic acid molecule compπsing the sequence of nucleotides of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13, or the complement of said nucleic acid molecule

5 The isolated nucleic acid molecule of claim 1, said molecule encoding a polypeptide comprising the ammo acid sequence of SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , or an amino acid sequence comprising one or more conservative substitutions in the amino acid sequence of SEQ ID NO 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21

6 An oligonucleotide less than 100 nucleotides in length and comprising at lease 6 contiguous nucleotides of SEQ ID NO 1, 3, 5, 7, 9, 1 1 or 13, or a complement thereof

7 A nucleic acid vector comprising the nucleic acid molecule of claim 1

8 The nucleic acid vector of claim 7, wherein said vector is an expression vector

9. The vector of claim 7, further comprising a regulatory element operably linked to said nucleic acid molecule.

10. A host cell comprising the isolated nucleic acid molecule of claim 1.

1 1. An isolated GLUTX polypeptide at least 80% identical to a polypeptide selected from the group consisting of: a) a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 ; b) a fragment of a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 , wherein the fragment comprises at least 6 contiguous amino acids of SEQ ID NO:2; c) a derivative of a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 ; d) an analog of a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 ; e) a homolog of a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21; f) A variant GLUTX polypeptide from SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, wherein the amino terminal domain of said polypeptide does not include consecutive leucine residues; and g) a naturally occurring allelic variant of a polypeptide comprising an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21 ; wherein the polypeptide is encoded by a nucleic acid molecule that hybridizes to a nucleic acid molecule of SEQ ID NO: 1, 3, 5, 7, 9, 11 or 13 under stringent conditions.

12. The polypeptide of claim 11, wherein the polypeptide has a hexose transport activity.

13. An antibody that selectively binds to the polypeptide of claim 11, and fragments, homologs, analogs, and derivatives of said antibody.

14. A method of producing the polypeptide of claim 11, said method comprising the step of culturing the host cell of claim 10 under conditions in which the nucleic acid molecule is expressed.

15. A method of detecting the presence of the polypeptide of claim 1 1 in a sample, comprising contacting the sample with a compound that selectively binds to the polypeptide of claim 11 and determining whether the compound bound to the polypeptide of claim 1 1 is present in the sample.

16. A method of detecting the presence of a nucleic acid molecule of claim 1 in a sample, the method comprising contacting the sample with a nucleic acid probe or primer that selectively binds to the nucleic acid molecule and determining whether the nucleic acid probe or primer bound to the nucleic acid molecule of claim 1 is present in the sample.

17. A method for modulating the activity of the polypeptide of claim 11, the method comprising contacting a cell sample comprising the polypeptide of claim 11 with a compound that binds to said polypeptide in an amount sufficient to modulate the activity of the polypeptide.

18. A method of treating or preventing a disorder, said disorder being a hexose transport disorder, said method comprising administering to a subject in which such treatment or prevention is desired an amount of a therapeutic selected from the group consisting of: a) the nucleic acid of claim 1 ; b) the polypeptide of claim 11 ; and c) the antibody of claim 13; wherein said therapeutic is administered in an amount sufficient to treat or prevent hexose transport disorder in said subject.

19. A pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a therapeutic selected from the group consisting of: a) the nucleic acid of claim 1 ; b) the polypeptide of claim 11 ; and c) the antibody of claim 13; and a pharmaceutically acceptable carrier.

20. A kit comprising in one or more containers, a therapeutically or prophylactically effective amount of the pharmaceutical composition of claim 19.

21. The use of a therapeutic in the manufacture of a medicament for treating a syndrome associated with a human disease, the disease being a hexose transport disorder, wherein said therapeutic is selected from the group consisting of: a) the nucleic acid of claim 1 ; b) the polypeptide of claim 1 1 ; and c) the antibody of claim 13.

22. A method for screening for a modulator of activity or of latency or predisposition to hexose transport disorder, said method comprising: a) administering a test compound to a test animal at increased risk for any one of a proliferative disorder, a differentiative disorder, and a glia-associated disorder, wherein said test animal recombinantly expresses a GLUTX protein; b) measuring expression the activity of said protein in said test animal; c) measuring the activity of said protein in a control animal that recombinantly expresses said protein and is not at increased risk for any one of a proliferative disorder, a differentiative disorder, and a glia-associated disorder; and d) comparing expression of said protein in said test animal and said control animal, wherein a change in the activity of said protein in said test animal relative to said control animal indicates the test compound is a modulator of latency of any one of a proliferative disorder, a differentiative disorder, and a glia-associated disorder.

23. The method of claim 22, wherein said test animal is a recombinant test animal that expresses a test protein transgene or expresses said transgene under the control of a promoter at an increased level relative to a wild-type test animal, and wherein said promoter is not the native gene promoter of said transgene.

24. A method for determining the presence of or predisposition to a disease associated with altered levels of a GLUTX polypeptide of claim 11, the method comprising: a) measuring the amount of the polypeptide in a sample from the mammalian subject; and b) comparing the amount of said polypeptide in step (a) to the amount of the polypeptide present in a control sample, wherein an alteration in the level of the polypeptide in step (a) as compared to the control sample indicates a disease condition.

25. A method for determining the presence of or predisposition to a disease associated with altered levels of a GLUTX nucleic acid of claim 1, the method comprising: a) measuring the amount of the nucleic acid in a sample from the mammalian subject; and b) comparing the amount of said nucleic acid in step (a) to the amount of the nucleic acid present in a control sample, wherein an alteration in the level of the nucleic acid in step (a) as compared to the control sample indicates a disease condition.

26. A method of treating a pathological state in a mammal, the method comprising administering to the subject a polypeptide to a subject in an amount to alleviate the pathological condition, wherein the polypeptide a polypeptide having an amino acid sequence at least 85% identical to a polypeptide with an amino acid sequence of SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20 or 21, or a biologically active fragment thereof.

27. A method of treating a pathological state in a mammal, the method comprising administering to the subject the antibody of claim 13 in an amount sufficient to alleviate the pathological condition.

28. The method of claim 26, wherein the polypeptide is targeted to the brain.

29. The method of claim 26, wherein the polypeptide is targeted to the testes.

30. The method of claim 26, wherein the pathological state is any one hexose transport disorder selected from the group comprising ischemia, diabetes, hyperglycemia, hypoglycemia, a glucose metabolism disorder, and a neurodegenerative disease.