WO2002004510A2 - Gtp-binding proteins - Google Patents

Abstract

The invention provides human GTP-binding proteins (GTPB) and polynucleotides which identify and encode GTPB. The invention also provides expression vectors, host cells, antibodies, agonists, and antaganists. The invention also provides methods for diagnosing, treating, or preventing disorders associated with aberrant expression of GTPB.

Description

GTP-BINDING PROTEINS

TECHNICAL FIELD

This invention relates to nucleic acid and amino acid sequences of GTP-binding proteins and to the use of these sequences in the diagnosis, treatment, and prevention of cell proliferative, autoimmune/inflammatory, and immunodeficiency disorders, and in the assessment of the effects of exogenous compounds on the expression of nucleic acid and amino acid sequences of GTP-binding proteins.

BACKGROUND OF THE INVENTION

Guanine nucleotide binding proteins (GTP-binding proteins) participate in a wide range of regulatory functions in all eukaryotic cells, including metabolism, cellular growth, differentiation, signal transduction, c toskeletal organization, and intracellular vesicle transport and secretion. In higher organisms they are involved in signaling that regulates such processes as the immune response (Aussel, C. et al. (1988) J. Immunol. 140:215-220), apoptosis, differentiation, and cell proliferation including oncogenesis (Dhanasekaran, N. et al. (1998) Oncogene 17:1383-1394). Exchange of bound GDP for GTP followed by hydrolysis of GTP to GDP provides the energy that enables GTP-binding proteins to alter their conformation and interact with other cellular components. The superfamily of GTP-binding proteins consists of several families and may be grouped as translational factors, heterotrimeric GTP-binding proteins involved in transmembrane signaling processes (also called G- proteins), and low molecular weight (LMW) GTP-binding proteins including the proto-oncogene Ras proteins and products of rab, rap, rho, rac, smg21, smg25, YPT, SEC4, and ARF genes, and tubulins (Kaziro, Y. et al. (1991) Annu. Rev. Biochem. 60:349-400). In all cases, the GTPase activity is regulated through interactions with other proteins. Heterotrimeric GTP-binding proteins are composed of 3 subunits ( , β and γ) which, in their inactive conformation, associate as a trimer at the inner face of the plasma membrane. G« binds GDP or GTP and contains the GTPase activity. The βγ complex enhances binding of Gα to a receptor. Gγ is necessary for the folding and activity of Gβ (Neer, E.J. et al. (1994) Nature 371 :297-300). Multiple homologs of each subunit have been identified in mammalian tissues, and different combinations of subunits have specific functions and tissue specificities (Spiegel, A.M. (1997) J. Inher. Metab. Dis. 20:113-121). G protein activity is triggered by seven-transmembrane cell surface receptors (G-protein coupled receptors) which respond to lipid analogs, amino acids and their derivatives, peptides, cytokines, and specialized stimuli such as light, taste, and odor. Activation of the receptor by its stimulus causes the replacement of the G protein-bound GDP with GTP. Gα-GTP dissociates from the receptor/βγ complex, and each of these separated components can interact with and regulate downstream effectors. The signaling stops when G« hydrolyzes its bound GTP to GDP and reassociates with the βγ complex (Neer, supra). The alpha subunits of heterotrimeric G proteins can be divided into four distinct classes. The a-s class is sensitive to ADP-ribosylation by pertussis toxin which uncouples the receptor:G-protein interaction. This uncoupling blocks signal transduction to receptors that decrease cAMP levels which normally regulate ion channels and activate phospholipases. The inhibitory cc-I class is also susceptible to modification by pertussis toxin which prevents -I from lowering cAMP levels. Two novel classes of α subunits refractory to pertussis toxin modification are α-q, which activates phospholipase C, and α-12, which has sequence homology with the Drosophila gene concertina and may contribute to the regulation of embryonic development (Simon, M.I. (1991) Science 252:802-808).

The mammalian Gβ and Gγ subunits, each about 340 amino acids long, share more than 80% homology. The Gβ subunit (also called transducin) contains seven repeating units, each about 43 amino acids long. The activity of both subunits may be regulated by other proteins such as calmodulin and phosducin or the neural protein GAP 43 (Clapham, D. and E. Neer (1993) Nature 365:403-406). The β and γ subunits are tightly associated. The β subunit sequences are highly conserved between species, implying that they perform a fundamentally important role in the organization and function of G-protein linked systems (Van der Voorn, L. (1992) FEBS Lett. 307:131-134). They contain seven tandem repeats of the WD-repeat sequence motif, a motif found in many proteins with regulatory functions. WD-repeat proteins contain from four to eight copies of a loosely conserved repeat of approximately 40 amino acids which participates in protein-protein interactions. Mutations and variant expression of β transducin proteins are linked with various disorders. Mutations in LIS1, a subunit of the human platelet activating factor acetylhydrolase, cause Miller-Dieker lissencephaly. RACK1 binds activated protein kinase C, and RbAp48 binds retinoblastoma protein. CstF is required for polyadenylation of mammalian pre-mRNA in vitro and associates with subunits of cleavage-stimulating factor. Defects in the regulation of b-catenin contribute to the neoplastic transformation of human cells. The WD40 repeats of the human F-box protein βTrCP mediate binding to β-catenin, thus regulating the targeted degradation of β-catenin by ubiquitin ligase (Neer, supra; Hart, M. et al. (1999) Curr. Biol. 9:207-210). The γ subunit primary structures are more variable than those of the β subunits. They are often post-translationally modified by isoprenylation and carboxyl- ethylation of a cysteine residue four amino acids from the C-terminus; this appears to be necessary for the interaction of the βγ subunit with the membrane and with other GTP-binding proteins. The βγ subunit has been shown to modulate the activity of isoforms of adenylyl cyclase, phospholipase C, and some ion channels. It is involved in receptor phosphorylation via specific kinases, and has been implicated in the p2 lras-dependent activation of the MAP kinase cascade and the recognition of specific receptors by GTP-binding proteins. (Clapham and Neer, supra). G-proteins interact with a variety of effectors including adenylyl cyclase (Clapham and Neer, supra). The signaling pathway mediated by cAMP is mitogenic in hormone-dependent endocrine tissues such as adrenal cortex, thyroid, ovary, pituitary, and testes. Cancers in these tissues have been related to a mutationally activated form of a Gα₅ known as the gsp (Gs protein) oncogene (Dhanasekaran, supra). Another effector is phosducin, a retinal phosphoprotein, which forms a specific complex with retinal Gβ and Gγ (Gβγ) and modulates the ability of Gβγ to interact with retinal G<χ (Clapham and Neer, supra).

Irregularities in the GTP-binding protein signaling cascade may result in abnormal activation of leukocytes and lymphocytes, leading to the tissue damage and destruction seen in many inflammatory and autoimmune diseases such as rheumatoid arthritis, biliary cirrhosis, hemolytic anemia, lupus erythematosus, and thyroiditis. Abnormal cell proliferation, including cyclic AMP stimulation of brain, thyroid, adrenal, and gonadal tissue proliferation is regulated by G proteins. Mutations in Gα subunits have been found in growth-hormone-secreting pituitary somatotroph tumors, hyperfunctioning thyroid adenomas, and ovarian and adrenal neoplasms (Meij, J.T.A. (1996) Mol. CeU. Biochem. 157:31-38; Aussel, supra). LMW GTP-binding proteins are GTPases which regulate cell growth, cell cycle control, protein secretion, and intracellular vesicle interaction. They consist of single polypeptides which, like the alpha subunit of the heterotrimeric GTP-binding proteins, are able to bind to and hydrolyze GTP, thus cycling between an inactive and an active state. LMW GTP-binding proteins respond to extracellular signals from receptors and activating proteins by transducing mitogenic signals involved in various cell functions. The binding and hydrolysis of GTP regulates the response of LMW GTP- binding proteins and acts as an energy source during this process (Bokoch, G.M. and C.J. Der (1993) FASEB J. 7:750-759).

At least sixty members of the LMW GTP-binding protein superfamily have been identified and are currently grouped into the ras, rho, arf, sari, ran, and rab subfamilies. Activated ras genes were initially found in human cancers, and subsequent studies confirmed that ras function is critical in determining whether cells continue to grow or become differentiated. Rasl and Ras2 proteins stimulate adenylate cyclase (Kaziro, supra), affecting a broad array of cellular processes. Stimulation of cell surface receptors activates Ras which, in turn, activates cytoplasmic kinases. These kinases translocate to the nucleus and activate key transcription factors that control gene expression and protein synthesis (Barbacid, M. (1987) Annu. Rev Biochem. 56:779-827; Treisman, R. (1994) Curr. Opin. Genet. Dev. 4:96-98). Other members of the LMW GTP-binding protein superfamily have roles in signal transduction that vary with the function of the activated genes and the locations of the GTP- binding proteins that initiate the activity. Rho GTP-binding proteins control signal transduction pathways that link growth factor receptors to actin polymerization, which is necessary for normal cellular growth and division. The rab, arf, and sari families of proteins control the translocation of vesicles to and from membranes for protein processing, localization, and secretion. Vesicle- and target- specific identifiers (v-SNAREs and t-SNAREs) bind to each other and dock the vesicle to the acceptor membrane. The budding process is regulated by the closely related ADP ribosylation factors (ARFs) and SAR proteins, while rab proteins allow assembly of SNARE complexes and may play a role in removal of defective complexes (Rothman, J. and F. Wieland (1996) Science 272:227-234). Ran GTP-binding proteins are located in the nucleus of cells and have a key role in nuclear protein import, the control of DNA synthesis, and cell-cycle progression (Hall, A. (1990) Science 249:635- 640; Barbacid, M. (1987) Annu. Rev Biochem. 56:779-827; Ktistakis, N. (1998) BioEssays 20:495- 504; and Sasaki, T. and Y. Takai (1998) Biochem. Biophys. Res. Commun. 245:641-645).

A member of the ARF family of GTP-binding proteins is centaurin beta 1 A, a regulator of membrane traffic and the actin cytoskeleton. The centaurin β family of GTPase-activating proteins (GAPs) and Arf guanine nucleotide exchange factors contain pleckstrin homology (PH) domains which are activated by phosphoinositides. PH domains bind phosphoinositides, implicating PH domains in signaling processes. Phosphoinositides have a role in converting Arf-GTP to Arf-GDP via the centaurin β family and a role in Arf activation (Kam, J.L. et al. (2000) J. Biol. Chem. 275:9653-9663). The rho GAP family is also implicated in the regulation of actin polymerization at the plasma membrane and in several cellular processes. The gene ARHGAP6 encodes GTPase-activating protein 6 isoform 4. Mutations in ARHGAP6, seen as a deletion of a 500 kb critical region in Xp22.3, causes the syndrom microphthalmia with linear skin defects (MLS). MLS is an X-linked dominant, male-lethal syndrome (Prakash, S.K. et al. (2000) Hum. Mol. Genet. 9:477-488).

Rab proteins are low molecular weight (LMW) guanidine triphosphatases (GTPases) and belong to the Ras superfamily. These proteins assist the binding of transport vesicles to their accepter organelles and initiate the vesicle fusion process using the energy from the hydrolysis of GTP. Rab proteins have a highly variable amino terminus containing membrane-specific signal information and a prenylated carboxy terminus which determines the target membrane to which the Rab proteins anchor. More than 30 Rab proteins have been identified in a variety of species, and each has a characteristic intracellular location and distinct transport function. In particular, Rabl and Rab2 are important in ER-to-Golgi transport; Rab3 transports secretory vesicles to the extracellular membrane; Rab5 is localized to endosomes and regulates the fusion of early endosomes into late endosomes; Rab6 is specific to the Golgi apparatus and regulates intra-Golgi transport events; Rab7 and Rab9 stimulate the fusion of late endosomes and Golgi vesicles with lysosomes, respectively; and Rab 10 mediates vesicle fusion from the medial Golgi to the trans Golgi. Mutant forms of Rab proteins are able to block protein transport along a given pathway or alter the sizes of entire organelles. Therefore, Rabs play key regulatory roles in membrane trafficking (Schimmoller, LS. and S.R. Pfeffer (1998) J. Biol. Chem. 243:22161-22164).

A large family of Ras-like enzymes, the Rab GTPases, play key roles in the endocytic and secretory pathways. The function of Rab proteins in vesicular transport requires the cooperation of many other proteins. Specifically, the membrane-targeting process is assisted by a series of escort proteins (Khosravi-Far, R. et al. (1991) Proc. Natl. Acad. Sci. USA 88:6264-6268). In the medial Golgi, it has been shown that GTP-bound Rab proteins initiate the binding of VAMP-like proteins of the transport vesicle to syntaxin-like proteins on the acceptor membrane, which subsequently triggers a cascade of protein-binding and membrane-fusion events. After transport, GTPase-activating proteins (GAPs) in the target membrane are responsible for converting the GTP-bound Rab proteins to their GDP-bound state. And finally, guanine-nucleotide dissociation inhibitor (GDI) recruites the GDP-bound proteins to their membrane of origin.

The cycling of LMW GTP-binding proteins between the GTP-bound active form and the GDP-bound inactive form is regulated by additional proteins. Guanosine nucleotide exchange factors (GEFs) increase the rate of nucleotide dissociation by several orders of magnitude, thus facilitating release of GDP and loading with GTP. The best characterized is the mammalian homologue of the Drosophila Son-of-Sevenless protein. Certain Ras-family proteins are also regulated by guanine nucleotide dissociation inhibitors (GDIs), which inhibit GDP dissociation. The intrinsic rate of GTP hydrolysis of the LMW GTP-binding proteins is typically very slow, but it can be stimulated by several orders of magnitude by GAPs (Geyer, M. and A. Wittinghofer (1997) Curr. Opin. Struct. Biol. 7:786- 792). Both GEF and GAP activity may be controlled in response to extracellular stimuli and modulated by accessory proteins such as RalBPl and POB 1. Mutant Ras-family proteins, which bind but can not hydrolyze GTP, are permanently activated, and cause cell proliferation or cancer, as do GEFs that inappropriately activate LMW GTP-binding proteins, such as the human oncogene NET1, a Rho-GEF (Drivas, G.T. et al. (1990) Mol. Cell. Biol. 10:1793-1798; Alberts, A.S. and R. Treisman (1998) EMBO J. 14:4075-4085).

The discovery of new GTP-binding proteins, and the polynucleotides encoding them, satisfies a need in the art by providing new compositions which are useful in the diagnosis, prevention, and treatment of cell proliferative, autoimmune/inflammatory, and immunodeficiency disorders, and in the assessment of the effects of exogenous compounds on the expression of nucleic acid and amino acid sequences of GTP-binding proteins.

SUMMARY OF THE INVENTION The invention features purified polypeptides, GTP-binding proteins, referred to collectively as

"GTPB" and individually as "GTPB-1," "GTPB-2," "GTPB-3," "GTPB-4," "GTPB-5," "GTPB-6," and "GTPB-7." hi one aspect, the invention provides an isolated polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO.T-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7. In one alternative, the invention provides an isolated polypeptide comprising the amino acid sequence of SEQ ID NO: 1-7. The invention further provides an isolated polynucleotide encoding a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l- 7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7. In one alternative, the polynucleotide encodes a polypeptide selected from the group consisting of SEQ ID NO.T-7. In another alternative, the polynucleotide is selected from the group consisting of SEQ ID NO:8-14. Additionally, the invention provides a recombinant polynucleotide comprising a promoter sequence operably linked to a polynucleotide encoding a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO.T-7. In one alternative, the invention provides a cell transformed with the recombinant polynucleotide. In another alternative, the invention provides a transgenic organism comprising the recombinant polynucleotide.

The invention also provides a method for producing a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO.T-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7. The method comprises a) culturing a cell under conditions suitable for expression of the polypeptide, wherein said cell is transformed with a recombinant polynucleotide comprising a promoter sequence operably linked to a polynucleotide encoding the polypeptide, and b) recovering the polypeptide so expressed.

Additionally, the invention provides an isolated antibody which specifically binds to a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO.T-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7.

The invention further provides an isolated polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, b) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). In one alternative, the polynucleotide comprises at least 60 contiguous nucleotides.

Additionally, the invention provides a method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, b) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ID NO:8-14, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). The method comprises a) hybridizing the sample with a probe comprising at least 20 contiguous nucleotides comprising a sequence complementary to said target polynucleotide in the sample, and which probe specifically hybridizes to said target polynucleotide, under conditions whereby a hybridization complex is formed between said probe and said target polynucleotide or fragments thereof, and b) detecting the presence or absence of said hybridization complex, and optionally, if present, the amount thereof. In one alternative, the probe comprises at least 60 contiguous nucleotides.

The invention further provides a method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide selected from the group consisting of a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, b) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, c) a polynucleotide complementary to the polynucleotide of a), d) a polynucleotide complementary to the polynucleotide of b), and e) an RNA equivalent of a)-d). The method comprises a) amplifying said target polynucleotide or fragment thereof using polymerase chain reaction amplification, and b) detecting the presence or absence of said amplified target polynucleotide or fragment thereof, and, optionally, if present, the amount thereof.

The invention further provides a composition comprising an effective amount of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO.T-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, and a pharmaceutically acceptable excipient. In one embodiment, the composition comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7. The invention additionally provides a method of treating a disease or condition associated with decreased expression of functional GTPB, comprising administering to a patient in need of such treatment the composition.

The invention also provides a method for screening a compound for effectiveness as an agonist of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO:l-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7. The method comprises a) exposing a sample comprising the polypeptide to a compound, and b) detecting agonist activity in the sample. In one alternative, the invention provides a composition comprising an agonist compound identified by the method and a pharmaceutically acceptable excipient. In another alternative, the invention provides a method of treating a disease or condition associated with decreased expression of functional GTPB, comprising administering to a patient in need of such treatment the composition.

Additionally, the invention provides a method for screening a compound for effectiveness as an antagonist of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from t e group consisting of SEQ ED NO:l-7. The method comprises a) exposing a sample comprising the polypeptide to a compound, and b) detecting antagonist activity in the sample. In one alternative, the invention provides a composition comprising an antagonist compound identified by the method and a pharmaceutically acceptable excipient. In another alternative, the invention provides a method of treating a disease or condition associated with overexpression of functional GTPB, comprising administering to a patient in need of such treatment the composition. The invention further provides a method of screening for a compound that specifically binds to a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO:l-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7. The method comprises a) combining the polypeptide with at least one test compound under suitable conditions, and b) detecting binding of the polypeptide to the test compound, thereby identifying a compound that specifically binds to the polypeptide.

The invention further provides a method of screening for a compound that modulates the activity of a polypeptide selected from the group consisting of a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, b) a polypeptide comprising a naturally occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7, c) a biologically active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO.T-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7. The method comprises a) combining the polypeptide with at least one test compound under conditions permissive for the activity of the polypeptide, b) assessing the activity of the polypeptide in the presence of the test compound, and c) comparing the activity of the polypeptide in the presence of the test compound with the activity of the polypeptide in the absence of the test compound, wherein a change in the activity of the polypeptide in the presence of the test compound is indicative of a compound that modulates the activity of the polypeptide. The invention further provides a method for screening a compound for effectiveness in altering expression of a target polynucleotide, wherein said target polynucleotide comprises a sequence selected from the group consisting of SEQ ID NO:8-14, the method comprising a) exposing a sample comprising the target polynucleotide to a compound, and b) detecting altered expression of the target polynucleotide. The invention further provides a method for assessing toxicity of a test compound, said method comprising a) treating a biological sample containing nucleic acids with the test compound; b) hybridizing the nucleic acids of the treated biological sample with a probe comprising at least 20 contiguous nucleotides of a polynucleotide selected from the group consisting of i) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, ii) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ED NO:8-14, iii) a polynucleotide having a sequence complementary to i), iv) a polynucleotide complementary to the polynucleotide of ii), and v) an RNA equivalent of i)-iv). Hybridization occurs under conditions whereby a specific hybridization complex is formed between said probe and a target polynucleotide in the biological sample, said target polynucleotide selected from the group consisting of i) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ID NO:8-14, ii) a polynucleotide comprising a naturally occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ID NO:8-14, iii) a polynucleotide complementary to the polynucleotide of i), iv) a polynucleotide complementary to the polynucleotide of ii), and v) an RNA equivalent of i)-iv). Alternatively, the target polynucleotide comprises a fragment of a polynucleotide sequence selected from the group consisting of i)-v) above; c) quantifying the amount of hybridization complex; and d) comparing the amount of hybridization complex in the treated biological sample with the amount of hybridization complex in an untreated biological sample, wherein a difference in the amount of hybridization complex in the treated biological sample is indicative of toxicity of the test compound.

BRIEF DESCRIPTION OF THE TABLES Table 1 summarizes the nomenclature for the full length polynucleotide and polypeptide sequences of the present invention.

Table 2 shows the GenBank identification number and annotation of the nearest GenBank homolog for polypeptides of the invention. The probability score for the match between each polypeptide and its GenBank homolog is also shown. Table 3 shows structural features of polypeptide sequences of the invention, including predicted motifs and domains, along with the methods, algorithms, and searchable databases used for analysis of the polypeptides.

Table 4 lists the cDNA and/or genomic DNA fragments which were used to assemble polynucleotide sequences of the invention, along with selected fragments of the polynucleotide sequences.

Table 5 shows the representative cDNA library for polynucleotides of the invention. Table 6 provides an appendix which describes the tissues and vectors used for construction of the cDNA libraries shown in Table 5.

Table 7 shows the tools, programs, and algorithms used to analyze the polynucleotides and polypeptides of the invention, along with applicable descriptions, references, and threshold parameters.

DESCRIPTION OF THE INVENTION

Before the present proteins, nucleotide sequences, and methods are described, it is understood that this invention is not limited to the particular machines, materials and methods described, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims.

It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a host cell" includes a plurality of such host cells, and a reference to "an antibody" is a reference to one or more antibodies and equivalents thereof known to those skilled in the art, and so forth. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any machines, materials, and methods similar or equivalent to those described herein can be used to practice or test the present invention, the preferred machines, materials and methods are now described. All publications mentioned herein are cited for the purpose of describing and disclosing the cell lines, protocols, reagents and vectors which are reported in the publications and which might be used in connection with the invention. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention. DEFINITIONS

"GTPB" refers to the amino acid sequences of substantially purified GTPB obtained from any species, particularly a mammalian species, including bovine, ovine, porcine, murine, equine, and human, and from any source, whether natural, synthetic, semi-synthetic, or recombinant.

The term "agonist" refers to a molecule which intensifies or mimics the biological activity of GTPB. Agonists may include proteins, nucleic acids, carbohydrates, small molecules, or any other compound or composition which modulates the activity of GTPB either by directly interacting with GTPB or by acting on components of the biological pathway in which GTPB participates.

An "allelic variant" is an alternative form of the gene encoding GTPB. Allelic variants may result from at least one mutation in the nucleic acid sequence and may result in altered mRNAs or in polypeptides whose structure or function may or may not be altered. A gene may have none, one, or many allelic variants of its naturally occumng form. Common mutational changes which give rise to allelic variants are generally ascribed to natural deletions, additions, or substitutions of nucleotides. Each of these types of changes may occur alone, or in combination with the others, one or more times in a given sequence.

"Altered" nucleic acid sequences encoding GTPB include those sequences with deletions, insertions, or substitutions of different nucleotides, resulting in a polypeptide the same as GTPB or a polypeptide with at least one functional characteristic of GTPB. Included within this definition are polymorphisms which may or may not be readily detectable using a particular oligonucleotide probe of the polynucleotide encoding GTPB, and improper or unexpected hybridization to allelic variants, with a locus other than the normal chromosomal locus for the polynucleotide sequence encoding GTPB. The encoded protein may also be "altered," and may contain deletions, insertions, or substitutions of amino acid residues which produce a silent change and result in a functionally equivalent GTPB. Deliberate amino acid substitutions may be made on the basis of similarity in polarity, charge, solubility, hydrophobicity, hydrophilicity, and/or the amphipathic nature of the residues, as long as the biological or immunological activity of GTPB is retained. For example, negatively charged amino acids may include aspartic acid and glutamic acid, and positively charged amino acids may include lysine and arginine. Amino acids with uncharged polar side chains having similar hydrophilicity values may include: asparagine and glutamine; and serine and threonine. Amino acids with uncharged side chains having similar hydrophilicity values may include: leucine, isoleucine, and valine; glycine and alanine; and phenylalanine and tyrosine.

The terms "amino acid" and "amino acid sequence" refer to an oligopeptide, peptide, polypeptide, or protein sequence, or a fragment of any of these, and to naturally occurring or synthetic molecules. Where "amino acid sequence" is recited to refer to a sequence of a naturally occurring protein molecule, "amino acid sequence" and like terms are not meant to limit the amino acid sequence to the complete native amino acid sequence associated with the recited protein molecule.

"Amplification" relates to the production of additional copies of a nucleic acid sequence. Amplification is generally carried out using polymerase chain reaction (PCR) technologies well known in the art.

The term "antagonist" refers to a molecule which inhibits or attenuates the biological activity of GTPB. Antagonists may include proteins such as antibodies, nucleic acids, carbohydrates, small molecules, or any other compound or composition which modulates the activity of GTPB either by directly interacting with GTPB or by acting on components of the biological pathway in which GTPB participates.

The term "antibody" refers to intact immunoglobulin molecules as well as to fragments thereof, such as Fab, F(ab')₂, and Fv fragments, which are capable of binding an epitopic determinant. Antibodies that bind GTPB polypeptides can be prepared using intact polypeptides or using fragments containing small peptides of interest as the immunizing antigen. The polypeptide or oligopeptide used to immunize an animal (e.g., a mouse, a rat, or a rabbit) can be derived from the translation of RNA, or synthesized chemically, and can be conjugated to a carrier protein if desired. Commonly used carriers that are chemically coupled to peptides include bovine serum albumin, thyroglobulin, and keyhole limpet hemocyanin (KLH). The coupled peptide is then used to immunize the animal.

The term "antigenic determinant" refers to that region of a molecule (i.e., an epitope) that makes contact with a particular antibody. When a protein or a fragment of a protein is used to immunize a host animal, numerous regions of the protein may induce the production of antibodies which bind specifically to antigenic determinants (particular regions or three-dimensional structures on the protein). An antigenic determinant may compete with the intact antigen (i.e., the immunogen used to elicit the immune response) for binding to an antibody. The term "antisense" refers to any composition capable of base-pairing with the "sense"

(coding) strand of a specific nucleic acid sequence. Antisense compositions may include DNA; RNA; peptide nucleic acid (PNA); oligonucleotides having modified backbone linkages such as phosphorothioates, methylphosphonates, or benzylphosphonates; oligonucleotides having modified sugar groups such as 2'-methoxyethyl sugars or 2'-methoxyethoxy sugars; or oligonucleotides having modified bases such as 5-methyl cytosine, 2'-deoxyuracil, or 7-deaza-2'-deoxyguanosine. Antisense molecules may be produced by any method including chemical synthesis or transcription. Once introduced into a cell, the complementary antisense molecule base-pairs with a naturally occurring nucleic acid sequence produced by the cell to form duplexes which block either transcription or translation. The designation "negative" or "minus" can refer to the antisense strand, and the designation "positive" or "plus" can refer to the sense strand of a reference DNA molecule.

The term "biologically active" refers to a protein having structural, regulatory, or biochemical functions of a naturally occurring molecule. Likewise, "immunologically active" or "immunogenic" refers to the capability of the natural, recombinant, or synthetic GTPB, or of any oligopeptide thereof, to induce a specific immune response in appropriate animals or cells and to bind with specific antibodies.

"Complementary" describes the relationship between two single-stranded nucleic acid sequences that anneal by base-pairing. For example, 5 -AGT-3' pairs with its complement, 3'-TCA-5'.

A "composition comprising a given polynucleotide sequence" and a "composition comprising a given amino acid sequence" refer broadly to any composition containing the given polynucleotide or amino acid sequence. The composition may comprise a dry formulation or an aqueous solution. Compositions comprising polynucleotide sequences encoding GTPB or fragments of GTPB may be employed as hybridization probes. The probes may be stored in freeze-dried form and may be associated with a stabilizing agent such as a carbohydrate. In hybridizations, the probe may be deployed in an aqueous solution containing salts (e.g., NaCl), detergents (e.g., sodium dodecyl sulfate; SDS), and other components (e.g., Denhardt's solution, dry milk, salmon sperm DNA, etc.). "Consensus sequence" refers to a nucleic acid sequence which has been subjected to repeated DNA sequence analysis to resolve uncalled bases, extended using the XE -PCR kit (Applied Biosystems, Foster City CA) in the 5' and/or the 3' direction, and resequenced, or which has been assembled from one or more overlapping cDNA, EST, or genomic DNA fragments using a computer program for fragment assembly, such as the GELVEEW fragment assembly system (GCG, Madison WE) or Phrap (University of Washington, Seattle WA). Some sequences have been both extended and assembled to produce the consensus sequence,

"Conservative amino acid substitutions" are those substitutions that are predicted to least interfere with the properties of the original protein, i.e., the structure and especially the function of the protein is conserved and not significantly changed by such substitutions. The table below shows amino acids which may be substituted for an original amino acid in a protein and which are regarded as conservative amino acid substitutions. Original Residue Conservative Substitution

Ala Gly, Ser

Arg His, Lys

Asn Asp, Gin, His Asp Asn, Glu

Cys Ala, Ser

Gin Asn, Glu, His

Glu Asp, Gin, His

Gly Ala His Asn, Arg, Gin, Glu

De E.eu, Val

Leu He, Val

Lys Arg, Gin, Glu

Met Leu, De Phe His, Met, Leu, Trp, Tyr

Ser Cys, Thr

Thr Ser, Val

Trp Phe, Tyr

Tyr His, Phe, Trp Val lie, Leu, Thr

Conservative amino acid substitutions generally maintain (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a beta sheet or alpha helical conformation, (b) the charge or hydrophobicity of the molecule at the site of the substitution, and or (c) the bulk of the side chain.

A "deletion" refers to a change in the amino acid or nucleotide sequence that results in the absence of one or more amino acid residues or nucleotides.

The term "derivative" refers to a chemically modified polynucleotide or polypeptide. Chemical modifications of a polynucleotide can include, for example, replacement of hydrogen by an alkyl, acyl, hydroxyl, or amino group. A derivative polynucleotide encodes a polypeptide which retains at least one biological or immunological function of the natural molecule. A derivative polypeptide is one modified by glycosylation, pegylation, or any similar process that retains at least one biological or immunological function of the polypeptide from which it was derived.

A "detectable label" refers to a reporter molecule or enzyme that is capable of generating a measurable signal and is covalently or noncovalently joined to a polynucleotide or polypeptide.

"Differential expression" refers to increased or upregulated; or decreased, downregulated, or absent gene or protein expression, determined by comparing at least two different samples. Such comparisons may be carried out between, for example, a treated and an untreated sample, or a diseased and a normal sample. A "fragment" is a unique portion of GTPB or the polynucleotide encoding GTPB which is identical in sequence to but shorter in length than the parent sequence. A fragment may comprise up to the entire length of the defined sequence, minus one nucleotide/amino acid residue. For example, a fragment may comprise from 5 to 1000 contiguous nucleotides or amino acid residues. A fragment used as a probe, primer, antigen, therapeutic molecule, or for other purposes, may be at least 5, 10, 15, 16, 20, 25, 30, 40, 50, 60, 75, 100, 150, 250 or at least 500 contiguous nucleotides or amino acid residues in length. Fragments may be preferentially selected from certain regions of a molecule. For example, a polypeptide fragment may comprise a certain length of contiguous amino acids selected from the first 250 or 500 amino acids (or first 25% or 50%) of a polypeptide as shown in a certain defined sequence. Clearly these lengths are exemplary, and any length that is supported by the specification, including the Sequence Listing, tables, and figures, may be encompassed by the present embodiments.

A fragment of SEQ ID NO: 8- 14 comprises a region of unique polynucleotide sequence that specifically identifies SEQ ED NO:8-14, for example, as distinct from any other sequence in the genome from which the fragment was obtained. A fragment of SEQ ED NO:8-14 is useful, for example, in hybridization and amplification technologies and in analogous methods that distinguish SEQ ED NO:8-l 4 from related polynucleotide sequences. The precise length of a fragment of SEQ ED NO:8-14 and the region of SEQ ED NO:8-14 to which the fragment corresponds are routinely determinable by one of ordinary skill in the art based on the intended purpose for the fragment.

A fragment of SEQ ED NO:l-7 is encoded by a fragment of SEQ ED NO:8-14. A fragment of SEQ ED NO: 1-7 comprises a region of unique amino acid sequence that specifically identifies SEQ ED NO: 1-7. For example, a fragment of SEQ ED NO: 1-7 is useful as an immunogenic peptide for the development of antibodies that specifically recognize SEQ ED NO:l-7. The precise length of a fragment of SEQ ED NO: 1-7 and the region of SEQ ED NO: 1-7 to which the fragment corresponds are routinely determinable by one of ordinary skill in the art based on the intended purpose for the fragment.

A "full length" polynucleotide sequence is one containing at least a translation initiation codon (e.g., methionine) followed by an open reading frame and a translation termination codon. A "full length" polynucleotide sequence encodes a "full length" polypeptide sequence.

"Homology" refers to sequence similarity or, interchangeably, sequence identity, between two or more polynucleotide sequences or two or more polypeptide sequences.

The terms "percent identity" and "% identity," as applied to polynucleotide sequences, refer to the percentage of residue matches between at least two polynucleotide sequences aligned using a standardized algoritiim. Such an algorithm may insert, in a standardized and reproducible way, gaps in the sequences being compared in order to optimize alignment between two sequences, and therefore achieve a more meaningful comparison of the two sequences.

Percent identity between polynucleotide sequences may be determined using the default parameters of the CLUSTAL V algorithm as incorporated into the MEGALIGN version 3.12e sequence alignment program. This program is part of the LASERGENE software package, a suite of molecular biological analysis programs (DNASTAR, Madison WI). CLUSTAL V is described in Higgins, D.G. and P.M. Sharp (1989) CABIOS 5:151-153 and in Higgins, D.G. et al. (1992) CABIOS 8:189-191. For pairwise alignments of polynucleotide sequences, the default parameters are set as follows: Ktuple=2, gap penalty=5, window=4, and "diagonals saved"=4. The "weighted" residue weight table is selected as the default. Percent identity is reported by CLUSTAL V as the "percent similarity" between aligned polynucleotide sequences.

Alternatively, a suite of commonly used and freely available sequence comparison algorithms is provided by the National Center for Biotechnology Information (NCBI) Basic Ex)cal Alignment Search Tool (BLAST) (Altschul, S.F. et al. (1990) J. Mol. Biol. 215:403-410), which is available from several sources, including the NCBI, Bethesda, MD, and on the Internet at http://www.ncbi.nlm.nih.gov/BLAST/. The BLAST software suite includes various sequence analysis programs including "blastn," that is used to align a known polynucleotide sequence with other polynucleotide sequences from a variety of databases. Also available is a tool called "BLAST 2 Sequences" that is used for direct pairwise comparison of two nucleotide sequences. "BLAST 2 Sequences" can be accessed and used interactively at http://www.ncbi.nlm.nih.gov/gorf/bl2.htrnl. The "BLAST 2 Sequences" tool can be used for both blastn and blastp (discussed below). BLAST programs are commonly used with gap and other parameters set to default settings. For example, to compare two nucleotide sequences, one may use blastn with the "BLAST 2 Sequences" tool Version 2.0.12 (April-21-2000) set at default parameters. Such default parameters may be, for example:

Matrix: BLOSUM62

Reward for match: 1

Penalty for mismatch: -2 Open Gap: 5 and Extension Gap: 2 penalties

Gap x drop-off: 50

Expect: 10

Word Size: 11

Filter: on Percent identity may be measured over the length of an entire defined sequence, for example, as defined by a particular SEQ ID number, or may be measured over a shorter length, for example, over the length of a fragment taken from a larger, defined sequence, for instance, a fragment of at least 20, at least 30, at least 40, at least 50, at least 70, at least 100, or at least 200 contiguous nucleotides. Such lengths are exemplary only, and it is understood that any fragment length supported by the sequences shown herein, in the tables, figures, or Sequence Listing, may be used to describe a length over which percentage identity may be measured.

Nucleic acid sequences that do not show a high degree of identity may nevertheless encode similar amino acid sequences due to the degeneracy of the genetic code. It is understood that changes in a nucleic acid sequence can be made using this degeneracy to produce multiple nucleic acid sequences that all encode substantially the same protein.

The phrases "percent identity" and "% identity," as applied to polypeptide sequences, refer to the percentage of residue matches between at least two polypeptide sequences aligned using a standardized algorithm. Methods of polypeptide sequence alignment are well-known. Some alignment methods take into account conservative amino acid substitutions. Such conservative substitutions, explained in more detail above, generally preserve the charge andjiydrophobicity at the site of substitution, thus preserving the structure (and therefore function) of the polypeptide.

Percent identity between polypeptide sequences may be determined using the default parameters of the CLUSTAL V algorithm as incorporated into the MEGALIGN version 3.12e sequence alignment program (described and referenced above). For pairwise alignments of polypeptide sequences using CLUSTAL V, the default parameters are set as follows: Ktuple=l, gap penalty=3, window=5, and "diagonals saved"=5. The PAM250 matrix is selected as the default residue weight table. As with polynucleotide alignments, the percent identity is reported by CLUSTAL V as the "percent similarity" between aligned polypeptide sequence pairs. Alternatively the NCBI BLAST software suite may be used. For example, for a pairwise comparison of two polypeptide sequences, one may use the "BLAST 2 Sequences" tool Version 2.0.12 (April-21-2000) with blastp set at default parameters. Such default parameters may be, for example: 5 Matrix: BLOSUM62

Open Gap: 11 and Extension Gap: 1 penalties

Gap x drop-off: 50

Expect: 10

Word Size: 3 10 Filter: on

Percent identity may be measured over the length of an entire defined polypeptide sequence, for example, as defined by a particular SEQ ED number, or may be measured over a shorter length, for example, over the length of a fragment taken from a larger, defined polypeptide sequence, for instance, a fragment of at least 15, at least 20, at least 30, at least 40, at least 50, at least 70 or at least 15 150 contiguous residues. Such lengths are exemplary only, and it is understood that any fragment length supported by the sequences shown herein, in the tables, figures or Sequence Listing, may be used to describe a length over which percentage identity may be measured.

"Human artificial chromosomes" (HACs) are linear microchromosomes which may contain DNA sequences of about 6 kb to 10 Mb in size and which contain all of the elements required for 0 chromosome replication, segregation and maintenance.

The term "humanized antibody" refers to an antibody molecule in which the amino acid sequence in the non-antigen binding regions has been altered so that the antibody more closely resembles a human antibody, and still retains its original binding ability.

"Hybridization" refers to the process by which a polynucleotide strand anneals with a 5 complementary strand through base pairing under defined hybridization conditions. Specific hybridization is an indication that two nucleic acid sequences share a high degree of complementarity. Specific hybridization complexes form under permissive annealing conditions and remain hybridized after the "washing" step(s). The washing step(s) is particularly important in determining the stringency of the hybridization process, with more stringent conditions allowing less non-specific 0 binding, i.e., binding between pairs of nucleic acid strands that are not perfectly matched. Permissive conditions for annealing of nucleic acid sequences are routinely determinable by one of ordinary skill in the art and may be consistent among hybridization experiments, whereas wash conditions may be varied among experiments to achieve the desired stringency, and therefore hybridization specificity. Permissive annealing conditions occur, for example, at 68 °C in the presence of about 6 x SSC, about 1% (w/v) SDS, and about 100 μg/ml sheared, denatured salmon sperm DNA.

Generally, stringency of hybridization is expressed, in part, with reference to the temperature under which the wash step is carried out. Such wash temperatures are typically selected to be about 5°C to 20°C lower than the thermal melting point (T_j-) for the specific sequence at a defined ionic strength and pH. The T_m is the temperature (under defined ionic strength and pH) at which 50% of the target sequence hybridizes to a perfectly matched probe. An equation for calculating T_m and conditions for nucleic acid hybridization are well known and can be found in Sambrook, J. et al. (1989) Molecular Cloning: A Laboratory Manual, 2^nd ed., vol. 1-3, Cold Spring Harbor Press, Plainview NY; specifically see volume 2, chapter 9.

High stringency conditions for hybridization between polynucleotides of the present invention include wash conditions of 68°C in the presence of about 0.2 x SSC and about 0.1 % SDS, for 1 hour. Alternatively, temperatures of about 65°C, 60°C, 55°C, or 42°C may be used. SSC concentration may be varied from about 0.1 to 2 x SSC, with SDS being present at about 0.1 %. Typically, blocking reagents are used to block non-specific hybridization. Such blocking reagents include, for instance, sheared and denatured salmon sperm DNA at about 100-200 μg/ml. Organic solvent, such as formamide at a concentration of about 35-50% v/v, may also be used under particular circumstances, such as for RNA:DNA hybridizations. Useful variations on these wash conditions will be readily apparent to those of ordinary skill in the art. Hybridization, particularly under high stringency conditions, may be suggestive of evolutionary similarity between the nucleotides. Such similarity is strongly indicative of a similar role for the nucleotides and their encoded polypeptides.

The term "hybridization complex" refers to a complex formed between two nucleic acid sequences by virtue of the formation of hydrogen bonds between complementary bases. A hybridization complex may be formed in solution (e.g., C₀t or R₀t analysis) or formed between one nucleic acid sequence present in solution and another nucleic acid sequence immobilized on a solid support (e.g., paper, membranes, filters, chips, pins or glass slides, or any other appropriate substrate to which cells or their nucleic acids have been fixed).

The words "insertion" and "addition" refer to changes in an amino acid or nucleotide sequence resulting in the addition of one or more amino acid residues or nucleotides, respectively. "Immune response" can refer to conditions associated with inflammation, trauma, immune disorders, or infectious or genetic disease, etc. These conditions can be characterized by expression of various factors, e.g., cytokines, chemokines, and other signaling molecules, which may affect cellular and systemic defense systems. An "immunogenic fragment" is a polypeptide or oligopeptide fragment of GTPB which is capable of eliciting an immune response when introduced into a living organism, for example, a mammal. The term "immunogenic fragment" also includes any polypeptide or oligopeptide fragment of GTPB which is useful in any of the antibody production methods disclosed herein or known in the art. The term "microarray" refers to an arrangement of a plurality of polynucleotides, polypeptides, or other chemical compounds on a substrate.

The terms "element" and "array element" refer to a polynucleotide, polypeptide, or other chemical compound having a unique and defined position on a microarray.

The term "modulate" refers to a change in the activity of GTPB. For example, modulation may cause an increase or a decrease in protein activity, binding characteristics, or any other biological, functional, or immunological properties of GTPB.

The phrases "nucleic acid" and "nucleic acid sequence" refer to a nucleotide, oligonucleotide, polynucleotide, or any fragment thereof. These phrases also refer to DNA or RNA of genomic or synthetic origin which may be single-stranded or double-stranded and may represent the sense or the antisense strand, to peptide nucleic acid (PNA), or to any DNA-like or RNA-like material.

"Operably linked" refers to the situation in which a first nucleic acid sequence is placed in a functional relationship with a second nucleic acid sequence. For instance, a promoter is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence. Operably linked DNA sequences may be in close proximity or contiguous and, where necessary to join two protein coding regions, in the same reading frame.

"Peptide nucleic acid" (PNA) refers to an antisense molecule or anti-gene agent which comprises an oligonucleotide of at least about 5 nucleotides in length linked to a peptide backbone of amino acid residues ending in lysine. The terminal lysine confers solubility to the composition. PNAs preferentially bind complementary single stranded DNA or RNA and stop transcript elongation, and may be pegylated to extend their lifespan in the cell.

"Post-translational modification" of an GTPB may involve lipidation, glycosylation, phosphorylation, acetylation, racemization, proteolytic cleavage, and other modifications known in the art. These processes may occur synthetically or biochemically. Biochemical modifications will vary by cell type depending on the enzymatic milieu of GTPB. "Probe" refers to nucleic acid sequences encoding GTPB, their complements, or fragments thereof, which are used to detect identical, allelic or related nucleic acid sequences. Probes are isolated oligonucleotides or polynucleotides attached to a detectable label or reporter molecule. Typical labels include radioactive isotopes, ligands, chemiluminescent agents, and enzymes. "Primers" are short nucleic acids, usually DNA oligonucleotides, which may be annealed to a target polynucleotide by complementary base-pairing. The primer may then be extended along the target DNA strand by a DNA polymerase enzyme. Primer pairs can be used for amplification (and identification) of a nucleic acid sequence, e.g., by the polymerase chain reaction (PCR). Probes and primers as used in the present invention typically comprise at least 15 contiguous nucleotides of a known sequence. In order to enhance specificity, longer probes and primers may also be employed, such as probes and primers that comprise at least 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, or at least 150 consecutive nucleotides of the disclosed nucleic acid sequences. Probes and primers may be considerably longer than these examples, and it is understood that any length supported by the specification, including the tables, figures, and Sequence Listing, may be used.

Methods for preparing and using probes and primers are described in the references, for example Sambrook, J. et al. (1989) Molecular Cloning: A Laboratory Manual, 2^nd ed., vol. 1-3, Cold Spring Harbor Press, Plainview NY; Ausubel, F.M. et al. (1 87) Current Protocols in Molecular Biology, Greene Publ. Assoc. & Wiley-Intersciences, New York NY; Innis, M. et al. (1990) PCR Protocols. A Guide to Methods and Applications, Academic Press, San Diego CA. PCR primer pairs can be derived from a known sequence, for example, by using computer programs intended for that purpose such as Primer (Version 0.5, 1991, Whitehead Institute for Biomedical Research, Cambridge MA).

Oligonucleotides for use as primers are selected using software known in the art for such purpose. For example, OLIGO 4.06 software is useful for the selection of PCR primer pairs of up to 100 nucleotides each, and for the analysis of oligonucleotides and larger polynucleotides of up to 5,000 nucleotides from an input polynucleotide sequence of up to 32 kilobases. Similar primer selection programs have incorporated additional features for expanded capabilities. For example, the PrimOU primer selection program (available to the public from the Genome Center at University of Texas South West Medical Center, Dallas TX) is capable of choosing specific primers from megabase sequences and is thus useful for designing primers on a genome-wide scope. The Primer3 primer selection program (available to the public from the Whitehead Institute/MIT Center for Genome Research, Cambridge MA) allows the user to input a "mispriming library," in which sequences to avoid as primer binding sites are user-specified. Primer3 is useful, in particular, for the selection of oligonucleotides for microarrays. (The source code for the latter two primer selection programs may also be obtained from their respective sources and modified to meet the user' s specific needs.) The PrimeGen program (available to the public from the UK Human Genome Mapping Project Resource Centre, Cambridge UK) designs primers based on multiple sequence alignments, thereby allowing selection of primers that hybridize to either the most conserved or least conserved regions of aligned nucleic acid sequences. Hence, this program is useful for identification of both unique and conserved oligonucleotides and polynucleotide fragments. The oligonucleotides and polynucleotide fragments identified by any of the above selection methods are useful in hybridization technologies, for example, as PCR or sequencing primers, microarray elements, or specific probes to identify fully or partially complementary polynucleotides in a sample of nucleic acids. Methods of oligonucleotide selection are not limited to those described above.

A "recombinant nucleic acid" is a sequence that is not naturally occurring or has a sequence that is made by an artificial combination of two or more otherwise separated segments of sequence. This artificial combination is often accomplished by chemical synthesis or, more commonly, by the artificial manipulation of isolated segments of nucleic acids, e.g., by genetic engineering techniques such as those described in Sambrook, supra. The term recombinant includes nucleic acids that have been altered solely by addition, substitution, or deletion of a portion of the nucleic acid. Frequently, a recombinant nucleic acid may include a nucleic acid sequence operably linked to a promoter sequence. Such a recombinant nucleic acid may be part of a vector that is used, for example, to transform a cell.

Alternatively, such recombinant nucleic acids may be part of a viral vector, e.g., based on a vaccinia virus, that could be use to vaccinate a mammal wherein the recombinant nucleic acid is expressed, inducing a protective immunological response in the mammal.

A "regulatory element" refers to a nucleic acid sequence usually derived from untranslated regions of a gene and includes enhancers, promoters, introns, and 5' and 3' untranslated regions (UTRs). Regulatory elements interact with host or viral proteins which control transcription, translation, or RNA stability.

"Reporter molecules" are chemical or biochemical moieties used for labeling a nucleic acid, amino acid, or antibody. Reporter molecules include radionuclides; enzymes; fluorescent, chemiluminescent, or chromogenic agents; substrates; cof actors; inhibitors; magnetic particles; and other moieties known in the art.

An "RNA equivalent," in reference to a DNA sequence, is composed of the same linear sequence of nucleotides as the reference DNA sequence with the exception that all occurrences of the nitrogenous base thymine are replaced with uracil, and the sugar backbone is composed of ribose instead of deoxyribose.

The term "sample" is used in its broadest sense. A sample suspected of containing GTPB, nucleic acids encoding GTPB, or fragments thereof may comprise a bodily fluid; an extract from a cell, chromosome, organelle, or membrane isolated from a cell; a cell; genomic DNA, RNA, or cDNA, in solution or bound to a substrate; a tissue; a tissue print; etc.

The terms "specific binding" and "specifically binding" refer to that interaction between a protein or peptide and an agonist, an antibody, an antagonist, a small molecule, or any natural or synthetic binding composition. The interaction is dependent upon the presence of a particular structure of the protein, e.g., the antigenic determinant or epitope, recognized by the binding molecule. For example, if an antibody is specific for epitope "A," the presence of a polypeptide comprising the epitope A, or the presence of free unlabeled A, in a reaction containing free labeled A and the antibody will reduce the amount of labeled A that binds to the antibody.

The term "substantially purified" refers to nucleic acid or amino acid sequences that are removed from their natural environment and are isolated or separated, and are at least 60% free, preferably at least 75% free, and most preferably at least 90% free from other components with which they are naturally associated.

A "substitution" refers to the replacement of one or more amino acid residues or nucleotides by different amino acid residues or nucleotides, respectively. "Substrate" refers to any suitable rigid or semi-rigid support including membranes, filters, chips, slides, wafers, fibers, magnetic or nonmagnetic beads, gels, tubing, plates, polymers, microparticles and capillaries. The substrate can have a variety of surface forms, such as wells, trenches, pins, channels and pores, to which polynucleotides or polypeptides are bound.

A "transcript image" refers to the collective pattern of gene expression by a particular cell type or tissue under given conditions at a given time.

"Transformation" describes a process by which exogenous DNA is introduced into a recipient cell. Transformation may occur under natural or artificial conditions according to various methods well known in the art, and may rely on any known method for the insertion of foreign nucleic acid sequences into a prokaryotic or eukaryotic host cell. The method for transformation is selected based on the type of host cell being transformed and may include, but is not limited to, bacteriophage or viral infection, electroporation, heat shock, lipofection, and particle bombardment. The term "transformed cells" includes stably transformed cells in which the inserted DNA is capable of replication either as an autonomously replicating plasmid or as part of the host chromosome, as well as transiently transformed cells which express the inserted DNA or RNA for limited periods of time. A "transgenic organism," as used herein, is any organism, including but not limited to animals and plants, in which one or more of the cells of the organism contains heterologous nucleic acid introduced by way of human intervention, such as by transgenic techniques well known in the art. The nucleic acid is introduced into the cell, directly or indirectly by introduction into a precursor of the cell, by way of deliberate genetic manipulation, such as by microinjection or by infection with a recombinant virus. The term genetic manipulation does not include classical cross-breeding, or in vitro fertilization, but rather is directed to the introduction of a recombinant DNA molecule. The transgenic organisms contemplated in accordance with the present invention include bacteria, cyanobacteria, fungi, plants and animals. The isolated DNA of the present invention can be introduced into the host by methods known in the art, for example infection, transfection, transformation or transconjugation. Techniques for transferring the DNA of the present invention into such organisms are widely known and provided in references such as Sambrook et al. (1989), supra.

A "variant" of a particular nucleic acid sequence is defined as a nucleic acid sequence having at least 40% sequence identity to the particular nucleic acid sequence over a certain length of one of the nucleic acid sequences using blastn with the "BLAST 2 Sequences" tool Version 2.0.9 (May-07- 1999) set at default parameters. Such a pair of nucleic acids may show, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% or greater sequence identity over a certain defined length. A variant may be described as, for example, an

"allelic" (as defined above), "splice," "species," or "polymorphic" variant. A splice variant may have significant identity to a reference molecule, but will generally have a greater or lesser number of polynucleotides due to alternative splicing of exons during mRNA processing. The corresponding polypeptide may possess additional functional domains or lack domains that are present in the reference molecule. Species variants are polynucleotide sequences that vary from one species to another. The resulting polypeptides will generally have significant amino acid identity relative to each other. A polymorphic variant is a variation in the polynucleotide sequence of a particular gene between individuals of a given species. Polymorphic variants also may encompass "single nucleotide polymorphisms" (SNPs) in which the polynucleotide sequence varies by one nucleotide base. The presence of SNPs may be indicative of, for example, a certain population, a disease state, or a propensity for a disease state.

A "variant" of a particular polypeptide sequence is defined as a polypeptide sequence having at least 40% sequence identity to the particular polypeptide sequence over a certain length of one of the polypeptide sequences using blastp with the "BLAST 2 Sequences" tool Version 2.0.9 (May-07- 1999) set at default parameters. Such a pair of polypeptides may show, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% or greater sequence identity over a certain defined length of one of the polypeptides. THE INVENTION

The invention is based on the discovery of new human GTP-binding proteins (GTPB), the polynucleotides encoding GTPB, and the use of these compositions for the diagnosis, treatment, or prevention of cell proliferative, autoimmune/inflammatory, and immunodeficiency disorders.

Table 1 summarizes the nomenclature for the full length polynucleotide and polypeptide sequences of the invention. Each polynucleotide and its corresponding polypeptide are correlated to a single Incyte project identification number (Incyte Project ED). Each polypeptide sequence is denoted by both a polypeptide sequence identification number (Polypeptide SEQ D NO:) and an Incyte polypeptide sequence number (Incyte Polypeptide ED) as shown. Each polynucleotide sequence is denoted by both a polynucleotide sequence identification number (Polynucleotide SEQ ED NO:) and an Incyte polynucleotide consensus sequence number (Incyte Polynucleotide ED) as shown.

Table 2 shows sequences with homology to the polypeptides of the invention as identified by BLAST analysis against the GenBank protein (genpept) database. Columns 1 and 2 show the polypeptide sequence identification number (Polypeptide SEQ ED NO:) and the corresponding Incyte polypeptide sequence number (Incyte Polypeptide D) for polypeptides of the invention. Column 3 shows the GenBank identification number (Genbank ID NO:) of the nearest GenBank homolog. Column 4 shows the probability score for the match between each polypeptide and its GenBank homolog. Column 5 shows the annotation of the GenBank homolog along with relevant citations where applicable, all of which are expressly incorporated by reference herein.

Table 3, shows various structural features of the polypeptides of the invention. Columns 1 and

2 show the polypeptide sequence identification number (SEQ ED NO:) and the corresponding Incyte polypeptide sequence number (Incyte Polypeptide ED) for each polypeptide of the invention. Column

3 shows the number of amino acid residues in each polypeptide. Column 4 shows potential phosphorylation sites, and column 5 shows potential glycosylation sites, as determined by the MOTIFS program of the GCG sequence analysis software package (Genetics Computer Group, Madison WE). Column 6 shows amino acid residues comprising signature sequences, domains, and motifs. Column 7 shows analytical methods for protein structure/function analysis and in some cases, searchable databases to which the analytical methods were applied. Together, Tables 2 and 3 summarize the properties of polypeptides of the invention, and these properties establish that the claimed polypeptides are GTP-binding proteins. For example, SEQ ID NO:l is 41 % identical to human centaurin β 1 A, which is an Arf GAP, a positive and negative regulator of Arf activity (GenBank ED g4225944), as determined by the Basic Local Alignment Search Tool (BLAST). (See Table 2.) The BLAST probability score is 1.5e-20, which indicates the probability of obtaining the observed polypeptide sequence alignment by chance. SEQ ID NO:l also contains a GTPase activating protein for Arf domain, a PH domain and a RhoGAP domain, as determined by searching for statistically significant matches in the hidden Markov model (HMM)- based PFAM database of conserved protein family domains. (See Table 3.) These HMMER-PFAM analyses provide further corroborative evidence that SEQ ID NO:l is a GTPase regulatory protein. SEQ ED NO:2-7 were analyzed and annotated in a similar manner. The algorithms and parameters for the analysis of SEQ ED NO:l-7 are described in Table 7.

As shown in Table 4, the full length polynucleotide sequences of the present invention were assembled using cDNA sequences or coding (exon) sequences derived from genomic DNA, or any combination of these two types of sequences. Columns 1 and 2 list the polynucleotide sequence identification number (Polynucleotide SEQ ID NO:) and the corresponding Incyte polynucleotide consensus sequence number (Incyte Polynucleotide ED) for each polynucleotide of the invention. Column 3 shows the length of each polynucleotide sequence in basepairs. Column 4 lists fragments of the polynucleotide sequences which are useful, for example, in hybridization or amplification technologies that identify SEQ ED NO:8-14 or that distinguish between SEQ ED NO:8-14 and related polynucleotide sequences. Column 5 shows identification numbers corresponding to cDNA sequences, coding sequences (exons) predicted from genomic DNA, and/or sequence assemblages comprised of both cDNA and genomic DNA. These sequences were used to assemble the full length polynucleotide sequences of the invention. Columns 6 and 7 of Table 4 show the nucleotide start (5') and stop (3') positions of the cDNA and/or genomic sequences in column 5 relative to their respective full length sequences.

The identification numbers in Column 5 of Table 4 may refer specifically, for example, to Encyte cDNAs along with their corresponding cDNA libraries. For example, 7197891H2 is the identification number of an Incyte cDNA sequence, and LUNGFER04 is the cDNA library from which it is derived. Incyte cDNAs for which cDNA libraries are not indicated were derived from pooled cDNA libraries (e.g., 71093821 VI). Alternatively, the identification numbers in column 5 may refer to GenBank cDNAs or ESTs (e.g., gl 670373) which contributed to the assembly of the full length polynucleotide sequences. In addition, the identification numbers in column 5 may identify sequences derived from the ENSEMBL (The Sanger Centre, Cambridge, UK) database (i.e., those sequences including the designation "ENST"). Alternatively, the identification numbers in column 5 may be derived from the NCBI RefSeq Nucleotide Sequence Records Database (Le., those sequences including the designation "NM" or "NT") or the NCBI RefSeq Protein Sequence Records (i.e., those sequences including the designation "NP"). Alternatively, the identification numbers in column 5 may refer to assemblages of both cDNA and Genscan-predicted exons brought together by an "exon stitching" algorithm. For example, VL_XXXXXX_N₁_N₂_YYYYY_N₃_N₄ represents a "stitched" sequence in which XXXXXX is the identification number of the cluster of sequences to which the algorithm was applied, and YYYYY is the number of the prediction generated by the algorithm, and N_{l 3.}.., if present, represent specific exons that may have been manually edited during analysis (See Example V). Alternatively, the identification numbers in column 5 may refer to assemblages of exons brought together by an "exon-stretching" algorithm. For example, FLXXXXKX_gAAAAA_gBBBBB_l_N is the identification number of a "stretched" sequence, with XXXXXX being the Incyte project identification number, gAAAAA being the GenBank identification number of the human genomic sequence to which the "exon-stretching" algorithm was applied, gBBBBB being the GenBank identification number or NCBI RefSeq identification number of the nearest GenBank protein homolog, and N referring to specific exons (See Example V). In instances where a RefSeq sequence was used as a protein homolog for the "exon-stretching" algorithm, a RefSeq identifier (denoted by "NM," "NP," or "NT") may be used in place of the GenB ank identifier (ie., gBBBBB).

Alternatively, a prefix identifies component sequences that were hand-edited, predicted from genomic DNA sequences, or derived from a combination of sequence analysis methods. The following Table lists examples of component sequence prefixes and corresponding sequence analysis methods associated with the prefixes (see Example IV and Example V).

In some cases, Incyte cDNA coverage redundant with the sequence coverage shown in column 5 was obtained to confirm the final consensus polynucleotide sequence, but the relevant Incyte cDNA identification numbers are not shown.

Table 5 shows the representative cDNA libraries for those full length polynucleotide sequences which were assembled using Incyte cDNA sequences. The representative cDNA library is the Incyte cDNA library which is most frequently represented by the incyte cDNA sequences which were used to assemble and confirm the above polynucleotide sequences. The tissues and vectors which were used to construct the cDNA libraries shown in Table 5 are described in Table 6.

The invention also encompasses GTPB variants. A preferred GTPB variant is one which has at least about 80%, or alternatively at least about 90%, or even at least about 95% amino acid sequence identity to the GTPB amino acid sequence, and which contains at least one functional or structural characteristic of GTPB.

The invention also encompasses polynucleotides which encode GTPB. In a particular embodiment, the invention encompasses a polynucleotide sequence comprising a sequence selected from the group consisting of SEQ ED NO:8-14, which encodes GTPB. The polynucleotide sequences of SEQ ED NO:8-14, as presented in the Sequence Listing, embrace the equivalent RNA sequences, wherein occurrences of the nitrogenous base thymine are replaced with uracil, and the sugar backbone is composed of ribose instead of deoxyribose.

The invention also encompasses a variant of a polynucleotide sequence encoding GTPB. In particular, such a variant polynucleotide sequence will have at least about 70%, or alternatively at least about 85%, or even at least about 95% polynucleotide sequence identity to the polynucleotide sequence encoding GTPB. A particular aspect of the invention encompasses a variant of a polynucleotide sequence comprising a sequence selected from the group consisting of SEQ ED NO:8- 14 which has at least about 70%, or alternatively at least about 85%, or even at least about 95% polynucleotide sequence identity to a nucleic acid sequence selected from the group consisting of SEQ ED NO:8-14. Any one of the polynucleotide variants described above can encode an amino acid sequence which contains at least one functional or structural characteristic of GTPB.

It will be appreciated by those skilled in the art that as a result of the degeneracy of the genetic code, a multitude of polynucleotide sequences encoding GTPB, some bearing minimal similarity to the polynucleotide sequences of any known and naturally occurring gene, may be produced. Thus, the invention contemplates each and every possible variation of polynucleotide sequence that could be made by selecting combinations based on possible codon choices. These combinations are made in accordance with the standard triplet genetic code as applied to the polynucleotide sequence of naturally occurring GTPB, and all such variations are to be considered as being specifically disclosed. Although nucleotide sequences which encode GTPB and its variants are generally capable of hybridizing to the nucleotide sequence of the naturally occurring GTPB under appropriately selected conditions of stringency, it may be advantageous to produce nucleotide sequences encoding GTPB or its derivatives possessing a substantially different codon usage, e.g., inclusion of non-naturally occurring codons. Codons may be selected to increase the rate at which expression of the peptide occurs in a particular prokaryotic or eukaryotic host in accordance with the frequency with which particular codons are utilized by the host. Other reasons for substantially altering the nucleotide sequence encoding GTPB and its derivatives without altering the encoded amino acid sequences include the production of RNA transcripts having more desirable properties, such as a greater half-life, than transcripts produced from the naturally occurring sequence.

The invention also encompasses production of DNA sequences which encode GTPB and GTPB derivatives, or fragments thereof, entirely by synthetic chemistry. After production, the synthetic sequence may be inserted into any of the many available expression vectors and cell systems using reagents well known in the art. Moreover, synthetic chemistry may be used to introduce mutations into a sequence encoding GTPB or any fragment thereof.

Also encompassed by the invention are polynucleotide sequences that are capable of hybridizing to the claimed polynucleotide sequences, and, in particular, to those shown in SEQ ED NO:8-14 and fragments thereof under various conditions of stringency. (See, e.g., Wahl, G.M. and S.L. Berger (1987) Methods Enzymol. 152:399-407; Kimmel, A.R. (1987) Methods Enzymol. 152:507- 511.) Hybridization conditions, including annealing and wash conditions, are described in "Definitions."

Methods for DNA sequencing are well known in the art and may be used to practice any of the embodiments of the invention. The methods may employ such enzymes as the Klenow fragment of DNA polymerase I, SEQUENASE (US Biochemical, Cleveland OH), Taq polymerase (Applied Biosystems), thermostable T7 polymerase (Amersham Pharmacia Biotech, Piscataway NJ), or combinations of polymerases and proofreading exonucleases such as those found in the ELONGASE amplification system (Life Technologies, Gaithersburg MD). Preferably, sequence preparation is automated with machines such as the MICROLAB 2200 liquid transfer system (Hamilton, Reno NV), PTC200 thermal cycler (MI Research, Watertown MA) and ABI CATALYST 800 thermal cycler (Applied Biosystems). Sequencing is then carried out using either the ABI 373 or 377 DNA sequencing system (Applied Biosystems), the MEGABACE 1000 DNA sequencing system (Molecular Dynamics, Sunnyvale CA), or other systems known in the art. The resulting sequences are analyzed using a variety of algorithms which are well known in the art. (See, e.g., Ausubel, F.M. (1997) Short Protocols in Molecular Biology, John Wiley & Sons, New York NY, unit 7.7; Meyers, R.A. (1995) Molecular Biology and Biotechnology, Wiley VCH, New York NY, pp. 856-853.)

The nucleic acid sequences encoding GTPB may be extended utilizing a partial nucleotide sequence and employing various PCR-based methods known in the art to detect upstream sequences, such as promoters and regulatory elements. For example, one method which may be employed, restriction-site PCR, uses universal and nested primers to amplify unknown sequence from genomic DNA within a cloning vector. (See, e.g., Sarkar, G. (1993) PCR Methods Applic. 2:318-322.) Another method, inverse PCR, uses primers that extend in divergent directions to amplify unknown sequence from a circularized template. The template is derived from restriction fragments comprising a known genomic locus and surrounding sequences. (See, e.g., Triglia, T. et al. (1988) Nucleic Acids Res. 16:8186.) A third method, capture PCR, involves PCR amplification of DNA fragments adjacent to known sequences in human and yeast artificial chromosome DNA. (See, e.g., Lagerstrom, M. et al. (1991) PCR Methods Applic. 1:111-119.) In this method, multiple restriction enzyme digestions and ligations may be used to insert an engineered double-stranded sequence into a region of unknown sequence before performing PCR. Other methods which may be used to retrieve unknown sequences are known in the art. (See, e.g., Parker, J.D. et al. (1991) Nucleic Acids Res. 19:3055-3060). Additionally, one may use PCR, nested primers, and PROMOTERFTNDER libraries (Clontech, Palo Alto CA) to walk genomic DNA. This procedure avoids the need to screen libraries and is useful in finding intron/exon junctions. For all PCR-based methods, primers may be designed using commercially available software, such as OLIGO 4.06 primer analysis software (National

Biosciences, Plymouth MN) or another appropriate program, to be about 22 to 30 nucleotides in length, to have a GC content of about 50% or more, and to anneal to the template at temperatures of about 68°C to 72°C.

When screening for full length cDNAs, it is preferable to use libraries that have been size-selected to include larger cDNAs. In addition, random-primed libraries, which often include sequences containing the 5' regions of genes, are preferable for situations in which an oligo d(T) library does not yield a full-length cDNA. Genomic libraries may be useful for extension of sequence into 5' non-transcribed regulatory regions.

Capillary electrophoresis systems which are commercially available may be used to analyze the size or confirm the nucleotide sequence of sequencing or PCR products. In particular, capillary sequencing may employ flowable polymers for electrophoretic separation, four different nucleotide- specific, laser-stimulated fluorescent dyes, and a charge coupled device camera for detection of the emitted wavelengths. Output/light intensity may be converted to electrical signal using appropriate software (e.g., GENOTYPER and SEQUENCE NAVIGATOR, Applied Biosystems), and the entire process from loading of samples to computer analysis and electronic data display may be computer controlled. Capillary electrophoresis is especially preferable for sequencing small DNA fragments which may be present in limited amounts in a particular sample.

In another embodiment of the invention, polynucleotide sequences or fragments thereof which encode GTPB may be cloned in recombinant DNA molecules that direct expression of GTPB, or fragments or functional equivalents thereof, in appropriate host cells. Due to the inherent degeneracy of the genetic code, other DNA sequences which encode substantially the same or a functionally equivalent amino acid sequence may be produced and used to express GTPB. The nucleotide sequences of the present invention can be engineered using methods generally known in the art in order to alter GTPB -encoding sequences for a variety of purposes including, but not limited to, modification of the cloning, processing, and/or expression of the gene product. DNA shuffling by random fragmentation and PCR reassembly of gene fragments and synthetic oligonucleotides may be used to engineer the nucleotide sequences. For example, oligonucleotide- mediated site-directed mutagenesis may be used to introduce mutations that create new restriction sites, alter glycosylation patterns, change codon preference, produce splice variants, and so forth.

The nucleotides of the present invention may be subjected to DNA shuffling techniques such as MOLECULARBREEDING (Maxygen Inc., Santa Clara CA; described in U.S. Patent Number 5,837,458; Chang, C.-C. et al. (1999) Nat. BiotechnoL 17:793-797; Christians, F.C. et al. (1999) Nat. BiotechnoL 17:259-264; and Crameri, A. et al. (1996) Nat. BiotechnoL 14:315-319) to alter or improve the biological properties of GTPB, such as its biological or enzymatic activity or its ability to bind to other molecules or compounds. DNA shuffling is a process by which a library of gene variants is produced using PCR-mediated recombination of gene fragments. The library is then subjected to selection or screening procedures that identify those gene variants with the desired properties. These preferred variants may then be pooled and further subjected to recursive rounds of DNA shuffling and selection screening. Thus, genetic diversity is created through "artificial" breeding and rapid molecular evolution. For example, fragments of a single gene containing random point mutations may be recombined, screened, and then reshuffled until the desired properties are optimized. Alternatively, fragments of a given gene may be recombined with fragments of homologous genes in the same gene family, either from the same or different species, thereby maximizing the genetic diversity of multiple naturally occurring genes in a directed and controllable manner.

In another embodiment, sequences encoding GTPB may be synthesized, in whole or in part, using chemical methods well known in the art. (See, e.g., Caruthers, M.H. et al. (1980) Nucleic Acids Symp. Ser. 7:215-223; and Horn, T. et al. (1980) Nucleic Acids Symp. Ser. 7:225-232.) Alternatively, GTPB itself or a fragment thereof may be synthesized using chemical methods. For example, peptide synthesis can be performed using various solution-phase or solid-phase techniques. (See, e.g., Creighton, T. (1984) Proteins, Structures and Molecular Properties, WH Freeman, New York NY, pp. 55-60; and Roberge, J.Y. et al. (1995) Science 269:202-204.) Automated synthesis maybe achieved using the ABI 431 A peptide synthesizer (Applied Biosystems). Additionally, the amino acid sequence of GTPB, or any part thereof, may be altered during direct synthesis and/or combined with sequences from other proteins, or any part thereof, to produce a variant polypeptide or a polypeptide having a sequence of a naturally occurring polypeptide. The peptide may be substantially purified by preparative high performance liquid chromatography. (See, e.g., Chiez, R.M. and F.Z. Regnier (1990) Methods Enzymol. 182:392-421.) The composition of the synthetic peptides may be confirmed by amino acid analysis or by sequencing. (See, e.g., Creighton, supra, pp. 28-53.)

En order to express a biologically active GTPB, the nucleotide sequences encoding GTPB or derivatives thereof may be inserted into an appropriate expression vector, Le., a vector which contains the necessary elements for transcriptional and translational control of the inserted coding sequence in a suitable host. These elements include regulatory sequences, such as enhancers, constitutive and inducible promoters, and 5' and 3 ' untranslated regions in the vector and in polynucleotide sequences encoding GTPB. Such elements may vary in their strength and specificity. Specific initiation signals may also be used to achieve more efficient translation of sequences encoding GTPB. Such signals include the ATG initiation codon and adjacent sequences, e.g. the Kozak sequence. In cases where sequences encoding GTPB and its initiation codon and upstream regulatory sequences are inserted into the appropriate expression vector, no additional transcriptional or translational control signals may be needed. However, in cases where only coding sequence, or a fragment thereof, is inserted, exogenous translational control signals including an in-frame ATG initiation codon should be provided by the vector. Exogenous translational elements and initiation codons may be of various origins, both natural and synthetic. The efficiency of expression may be enhanced by the inclusion of enhancers appropriate for the particular host cell system used. (See, e.g., Scharf, D. et al. (1994) Results Probl. CeU Differ. 20:125-162.) Methods which are well known to those skilled in the art may be used to construct expression vectors containing sequences encoding GTPB and appropriate transcriptional and translational control elements. These methods include in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. (See, e.g., Sambrook, J. et al. (1989) Molecular Cloning. A Laboratory Manual, Cold Spring Harbor Press, Plainview NY, ch. 4, 8, and 16-17; Ausubel, F.M. et al. (1995) Current Protocols in Molecular Biology, John Wiley & Sons, New York NY, ch. 9, 13, and 16.)

A variety of expression vector/host systems may be utilized to contain and express sequences encoding GTPB. These include, but are not limited to, microorganisms such as bacteria transformed with recombinant bacteriophage, plasmid, or cosmid DNA expression vectors; yeast transformed with yeast expression vectors; insect cell systems infected with viral expression vectors (e.g., baculovirus); plant cell systems transformed with viral expression vectors (e.g., cauliflower mosaic virus, CaMV, or tobacco mosaic virus, TMV) or with bacterial expression vectors (e.g., Ti or pBR322 plasmids); or animal cell systems. (See, e.g., Sambrook, supra; Ausubel, supra; Van Heeke, G. and S.M. Schuster (1989) J. Biol. Chem. 264:5503-5509; Engelhard, E.K. et al. (1994) Proc. Natl. Acad. Sci. USA 91:3224-3227; Sandig, V. et al. (1996) Hum. Gene Ther. 7:1937-1945; Takamatsu, N. (1987) EMBO J. 6:307-311 : The McGraw Hill Yearbook of Science and Technology (1992) McGraw Hill, New York NY, pp. 191-196; Logan, J. and T. Shenk (1984) Proc. Natl. Acad. Sci. USA 81:3655-3659; and Harrington, J.J. et al. (1997) Nat. Genet. 15:345-355.) Expression vectors derived from retroviruses, adenoviruses, or herpes or vaccinia viruses, or from various bacterial plasmids, may be used for delivery of nucleotide sequences to the targeted organ, tissue, or cell population. (See, e.g., Di Nicola, M. et al. (1998) Cancer Gen. Ther. 5(6):350-356; Yu, M. et al. (1993) Proc. Natl. Acad. Sci. USA 90(13):6340-6344; Buller, R.M. et al. (1985) Nature 317(6040):813-815; McGregor, D.P. et al. (1994) Mol. Immunol. 31(3):219-226; and Ver a, I.M. and N. Somia (1997) Nature 389:239-242.) The invention is not limited by the host cell employed.

In bacterial systems, a number of cloning and expression vectors may be selected depending upon the use intended for polynucleotide sequences encoding GTPB. For example, routine cloning, subcloning, and propagation of polynucleotide sequences encoding GTPB can be achieved using a multifunctional E. coli vector such as PBLUESCREPT (Stratagene, La Jolla CA) or PSPORT1 plasmid (Life Technologies). Ligation of sequences encoding GTPB into the vector's multiple cloning site disrupts the lacZ gene, allowing a colorimetric screening procedure for identification of transformed bacteria containing recombinant molecules. In addition, these vectors may be useful for in vitro transcription, dideoxy sequencing, single strand rescue with helper phage, and creation of nested deletions in the cloned sequence. (See, e.g., Van Heeke, G. and S.M. Schuster (1989) J. Biol. Chem. 264:5503-5509.) When large quantities of GTPB are needed, e.g. for the production of antibodies, vectors which direct high level expression of GTPB may be used. For example, vectors containing the strong, inducible SP6 or T7 bacteriophage promoter may be used.

Yeast expression systems may be used for production of GTPB. A number of vectors containing constitutive or inducible promoters, such as alpha factor, alcohol oxidase, and PGH promoters, may be used in the yeast Saccharomyces cerevisiae or Pichia pastoris. In addition, such vectors direct either the secretion or intracellular retention of expressed proteins and enable integration of foreign sequences into the host genome for stable propagation. (See, e.g., Ausubel, 1995, supra; Bitter, G.A. et al. (1987) Methods Enzymol. 153:516-544; and Scorer, CA. et al. (1994) BioTechnology 12:181-184.)

Plant systems may also be used for expression of GTPB. Transcription of sequences encoding GTPB may be driven by viral promoters, e.g., the 35S and 19S promoters of CaMV used alone or in combination with the omega leader sequence from TMV (Takamatsu, N. (1987) EMBO J. 6:307-311). Alternatively, plant promoters such as the small subunit of RUBISCO or heat shock promoters may be used. (See, e.g., Coruzzi, G. et al. (1984) EMBO J. 3:1671-1680; Broglie, R. et al. (1984) Science 224:838-843; and Winter, J. et al. (1991) Results Probl. CeU Differ. 17:85-105.) These constructs can be introduced into plant cells by direct DNA transformation or pathogen-mediated transfection. (See, e.g., The McGraw Hill Yearbook of Science and Technology (1992) McGraw Hill, New YorkNY, pp. 191-196.)

In mammalian cells, a number of viral-based expression systems may be utilized. In cases where an adenovirus is used as an expression vector, sequences encoding GTPB may be ligated into an adenovirus transcription/translation complex consisting of the late promoter and tripartite leader sequence. Insertion in a non-essential El or E3 region of the viral genome may be used to obtain infective virus which expresses GTPB in host cells. (See, e.g., Logan, J. and T. Shenk (1984) Proc. Natl. Acad. Sci. USA 81. '3655-3659.) In addition, transcription enhancers, such as the Rous sarcoma virus (RSV) enhancer, may be used to increase expression in mammalian host cells. SV40 or EB V- based vectors may also be used for high-level protein expression.

Human artificial chromosomes (HACs) may also be employed to deliver larger fragments of DNA than can be contained in and expressed from a plasmid. HACs of about 6 kb to 10 Mb are constructed and delivered via conventional delivery methods (liposomes, polycationic amino polymers, or vesicles) for therapeutic purposes. (See, e.g., Harrington, J.J. et al. (1997) Nat. Genet. 15:345- 355.)

For long term production of recombinant proteins in mammalian systems, stable expression of GTPB in cell lines is preferred. For example, sequences encoding GTPB can be transformed into cell lines using expression vectors which may contain viral origins of replication and/or endogenous expression elements and a selectable marker gene on the same or on a separate vector. Following the introduction of the vector, cells may be allowed to grow for about 1 to 2 days in enriched media before being switched to selective media. The purpose of the selectable marker is to confer resistance to a selective agent, and its presence allows growth and recovery of cells which successfully express the introduced sequences. Resistant clones of stably transformed cells may be propagated using tissue culture techniques appropriate to the cell type.

Any number of selection systems may be used to recover transformed cell lines. These include, but are not limited to, the herpes simplex virus thymidine kinase and adenine phosphoribosyltransferase genes, for use in tk and apr cells, respectively. (See, e.g., Wigler, M. et al. (1977) Cell 11:223-232; Lowy, I. et al. (1980) CeU 22:817-823.) Also, antimetaboHte, antibiotic, or herbicide resistance can be used as the basis for selection. For example, dhfr confers resistance to methotrexate; neo confers resistance to the aminoglycosides neomycin and G-418; and als and pat confer resistance to cMorsulfuron and phosphinotricin acetyltransferase, respectively. (See, e.g., Wigler, M. et al. (1980) Proc. Natl. Acad. Sci. USA 77:3567-3570; Colbere-Garapin, F. et al. (1981) J. Mol. Biol 150:1-14.) Additional selectable genes have been described, e.g., trpB and hisD, which alter ceUular requirements for metaboUtes. (See, e.g., Hartman, S.C. and R.C. Mulligan (1988) Proc. Natl. Acad. Sci. USA 85:8047-8051.) Visible markers, e.g., anthocyanins, green fluorescent proteins (GFP; Clontech), β glucuronidase and its substrate β-glucuronide, or luciferase and its substrate luciferin may be used. These markers can be used not only to identify transformants, but also to quantify the amount of transient or stable protein expression attributable to a specific vector system. (See, e.g., Rhodes, CA. (1995) Methods Mol. Biol. 55:121-131.) Although the presence/absence of marker gene expression suggests that the gene of interest is also present, the presence and expression of the gene may need to be confirmed. For example, if the sequence encoding GTPB is inserted within a marker gene sequence, transformed cells containing sequences encoding GTPB can be identified by the absence of marker gene function. Alternatively, a marker gene can be placed in tandem with a sequence encoding GTPB under the control of a single promoter. Expression of the marker gene in response to induction or selection usuaUy indicates expression of the tandem gene as weU.

In general, host ceUs that contain the nucleic acid sequence encoding GTPB and that express GTPB may be identified by a variety of procedures known to those of skiU in the art. These procedures include, but are not limited to, DNA-DNA or DNA-RNA hybridizations, PCR amplification, and protein bioassay or immunoassay techniques which include membrane, solution, or chip based technologies for the detection and/or quantification of nucleic acid or protein sequences.

Immunological methods for detecting and measuring the expression of GTPB using either specific polyclonal or monoclonal antibodies are known in the art. Examples of such techniques include enzyme-Unked immunosorbent assays (ELISAs), radioimmunoassays (REAs), and fluorescence activated ceU sorting (FACS). A two-site, monoclonal-based immunoassay utilizing monoclonal antibodies reactive to two non-interfering epitopes on GTPB is preferred, but a competitive binding assay may be employed. These and other assays are weU known in the art. (See, e.g., Hampton, R. et al. (1990) Serological Methods, a Laboratory Manual, APS Press, St. Paul MN, Sect. IV; CoUgan, J.E. et al. (1997) Current Protocols in Immunology, Greene Pub. Associates and Wiley-Enterscience, New York NY; and Pound, J.D. (1998) Immunochemical Protocols, Humana Press, Totowa NJ.)

A wide variety of labels and conjugation techniques are known by those skiUed in the art and may be used in various nucleic acid and amino acid assays. Means for producing labeled hybridization or PCR probes for detecting sequences related to polynucleotides encoding GTPB include oligolabeling, nick translation, end-labeling, or PCR ampUfication using a labeled nucleotide. Alternatively, the sequences encoding GTPB, or any fragments thereof, may be cloned into a vector for the production of an mRNA probe. Such vectors are known in the art, are commerciaUy available, and may be used to synthesize RNA probes in vitro by addition of an appropriate RNA polymerase such as T7, T3, or SP6 and labeled nucleotides. These procedures may be conducted using a variety of commercially available kits, such as those provided by Amersham Pharmacia Biotech, Promega (Madison WE), and US Biochemical. Suitable reporter molecules or labels which may be used for ease of detection include radionuclides, enzymes, fluorescent, chemiluminescent, or chromogenic agents, as weU as substrates, cofactors, inhibitors, magnetic particles, and the Uke.

Host cells transformed with nucleotide sequences encoding GTPB may be cultured under conditions suitable for the expression and recovery of the protein from cell culture. The protein produced by a transformed ceU may be secreted or retained intraceUularly depending on the sequence and/or the vector used. As wiU be understood by those of skiU in the art, expression vectors containing polynucleotides which encode GTPB may be designed to contain signal sequences which direct secretion of GTPB through a prokaryotic or eukaryotic cell membrane.

In addition, a host ceU strain may be chosen for its abihty to modulate expression of the inserted sequences or to process the expressed protein in the desired fashion. Such modifications of the polypeptide include, but are not limited to, acetylation, carboxylation, glycosylation, phosphorylation, Upidation, and acylation. Post-translational processing which cleaves a "prepro" or "pro" form of the protein may also be used to specify protein targeting, folding, and/or activity. Different host ceUs which have specific ceUular machinery and characteristic mechanisms for post-translational activities (e.g., CHO, HeLa, MDCK, HEK293, and WI38) are available from the American Type Culture CoUection (ATCC, Manassas VA) and may be chosen to ensure the correct modification and processing of the foreign protein.

En another embodiment of the invention, natural, modified, or recombinant nucleic acid sequences encoding GTPB may be ligated to a heterologous sequence resulting in translation of a fusion protein in any of the aforementioned host systems. For example, a chimeric GTPB protein containing a heterologous moiety that can be recognized by a commerciaUy available antibody may facihtate the screening of peptide Ubraries for inhibitors of GTPB activity. Heterologous protein and peptide moieties may also facihtate purification of fusion proteins using commerciaUy available affinity matrices. Such moieties include, but are not Umited to, glutathione S-transferase (GST), maltose binding protein (MBP), thioredoxin (Trx), calmoduUn binding peptide (CBP), 6-His, FLAG, c-myc, and hemagglutinin (HA). GST, MBP, Trx, CBP, and 6-His enable purification of their cognate fusion proteins on immobiUzed glutathione, maltose, phenylarsine oxide, caknoduUn, and metal-chelate resins, respectively. FLAG, c-myc, and hemagglutinin (HA) enable immunoaffinity purification of fusion proteins using commerciaUy available monoclonal and polyclonal antibodies that specificaUy recognize these epitope tags. A fusion protein may also be engineered to contain a proteolytic cleavage site located between the GTPB encoding sequence and the heterologous protein sequence, so that GTPB may be cleaved away from the heterologous moiety foUowing purification. Methods for fusion protein expression and purification are discussed in Ausubel (1995, supra, ch. 10). A variety of commerciaUy available kits may also be used to faciUtate expression and purification of fusion proteins. In a further embodiment of the invention, synthesis of radiolabeled GTPB may be achieved in vitro using the TNT rabbit reticulocyte lysate or wheat germ extract system (Promega). These systems couple transcription and translation of protein-coding sequences operably associated with the T7, T3, or SP6 promoters. Translation takes place in the presence of a radiolabeled amino acid precursor, for example, ³⁵S-methionine. GTPB of the present invention or fragments thereof may be used to screen for compounds that specificaUy bind to GTPB. At least one and up to a pluranty of test compounds may be screened for specific binding to GTPB. Examples of test compounds include antibodies, oUgonucleotides, proteins (e.g., receptors), or smaU molecules.

In one embodiment, the compound thus identified is closely related to the natural Ugand of GTPB, e.g., a Ugand or fragment thereof, a natural substrate, a structural or functional mimetic, or a natural binding partner. (See, e.g., CoUgan, J.E. et al. (1991) Current Protocols in Immunology 1(2): Chapter 5.) Similarly, the compound can be closely related to the natural receptor to which GTPB binds, or to at least a fragment of the receptor, e.g., the Ugand binding site. In either case, the compound can be rationaUy designed using known techniques. In one embodiment, screening for these compounds involves producing appropriate ceUs which express GTPB, either as a secreted protein or on the ceU membrane. Preferred ceUs include ceUs from mammals, yeast, Drosophila, or E. coU. CeUs expressing GTPB or ceU membrane fractions which contain GTPB are then contacted with a test compound and binding, stimulation, or inhibition of activity of either GTPB or the compound is analyzed.

An assay may simply test binding of a test compound to the polypeptide, wherein binding is detected by a fluorophore, radioisotope, enzyme conjugate, or other detectable label. For example, the assay may comprise the steps of combining at least one test compound with GTPB, either in solution or affixed to a soUd support, and detecting the binding of GTPB to the compound. Alternatively, the assay may detect or measure binding of a test compound in the presence of a labeled competitor. AdditionaUy, the assay may be carried out using ceU-free preparations, chemical Ubraries, or natural product mixtures, and the test compound(s) may be free in solution or affixed to a solid support. GTPB of the present invention or fragments thereof may be used to screen for compounds that modulate the activity of GTPB. Such compounds may include agonists, antagonists, or partial or inverse agonists. In one embodiment, an assay is performed under conditions permissive for GTPB activity, wherein GTPB is combined with at least one test compound, and the activity of GTPB in the presence of a test compound is compared with the activity of GTPB in the absence of the test compound. A change in the activity of GTPB in the presence of the test compound is indicative of a compound that modulates the activity of GTPB . Alternatively, a test compound is combined with an in vitro or ceU-free system comprising GTPB under conditions suitable for GTPB activity, and the assay is performed. In either of these assays, a test compound which modulates the activity of GTPB may do so indirectly and need not come in direct contact with the test compound. At least one and up to a plurality of test compounds may be screened. In another embodiment, polynucleotides encoding GTPB or their mammaUan homologs may be

"knocked out" in an animal model system using homologous recombination in embryonic stem (ES) ceUs. Such techniques are weU known in the art and are useful for the generation of animal models of human disease. (See, e.g., U.S. Patent Number 5,175,383 and U.S. Patent Number 5,767,337.) For example, mouse ES ceUs, such as the mouse 129/SvJ ceU Une, are derived from the early mouse embryo and grown in culture. The ES ceUs are transformed with a vector containing the gene of interest disrupted by a marker gene, e.g., the neomycin phosphotransferase gene (neo; Capecchi, M.R. (1989) Science 244:1288-1292). The vector integrates into the corresponding region of the host genome by homologous recombination. Alternatively, homologous recombination takes place using the Cre-loxP system to knockout a gene of interest in a tissue- or developmental stage-specific manner (Marth, J.D. (1996) CUn. Invest. 97:1999-2002; Wagner, K.U. et al. (1997) Nucleic Acids Res.

25:4323-4330). Transformed ES ceUs are identified and microinjected into mouse ceU blastocysts such as those from the C57BL/6 mouse strain. The blastocysts are surgicaUy transferred to pseudopregnant dams, and the resulting chimeric progeny are genotyped and bred to produce heterozygous or homozygous strains. Transgenic animals thus generated may be tested with potential therapeutic or toxic agents.

Polynucleotides encoding GTPB may also be manipulated in vitro in ES cells derived from human blastocysts. Human ES ceUs have the potential to differentiate into at least eight separate ceU Uneages including endoderm, mesoderm, and ectodermal ceU types. These ceU Uneages differentiate into, for example, neural ceUs, hematopoietic Uneages, and cardiomyocytes (Thomson, J.A. et al. (1998) Science 282:1145-1147).

Polynucleotides encoding GTPB can also be used to create "knockin" humanized animals (pigs) or transgenic animals (mice or rats) to model human disease. With knockin technology, a region of a polynucleotide encoding GTPB is injected into animal ES ceUs, and the injected sequence integrates into the animal ceU genome. Transformed ceUs are injected into blastulae, and the blastulae are implanted as described above. Transgenic progeny or inbred Unes are studied and treated with potential pharmaceutical agents to obtain information on freatment of a human disease. Alternatively, a mammal inbred to overexpress GTPB, e.g., by secreting GTPB in its milk, may also serve as a convenient source of that protein (Janne, J. et al. (1998) BiotechnoL Annu. Rev. 4:55-74). THERAPEUTICS

Chemical and structural similarity, e.g., in the context of sequences and motifs, exists between regions of GTPB and GTP-binding proteins. In addition, the expression of GTPB is closely associated with bladder tumor, arterial, dermal, and pituitary tissues. Therefore, GTPB appears to play a role in ceU proUferative, autoimmune/inflammatory, and immunodeficiency disorders. In the treatment of disorders associated with increased GTPB expression or activity, it is desirable to decrease the expression or activity of GTPB. In the treatment of disorders associated with decreased GTPB expression or activity, it is desirable to increase the expression or activity of GTPB.

Therefore, in one embodiment, GTPB or a fragment or derivative thereof may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of GTPB. Examples of such disorders include, but are not Umited to, a ceU proUferative disorder, such as actinic keratosis, arteriosclerosis, atherosclerosis, bursitis, cirrhosis, hepatitis, mixed connective tissue disease (MCTD), myelofibrosis, paroxysmal nocturnal hemoglobinuria, polycythemia vera, psoriasis, primary thrombocythemia, and cancers including adenocarcinoma, leukemia, lymphoma, melanoma, myeloma, sarcoma, teratocarcinoma, and, in particular, cancers of the adrenal gland, bladder, bone, bone marrow, brain, breast, cervix, gaU bladder, gangUa, gastrointestinal tract, heart, kidney, Uver, lung, muscle, ovary, pancreas, parathyroid, penis, prostate, saUvary glands, skin, spleen, testis, thymus, thyroid, and uterus, an autoimmune/inflammatory disorder, such as acquired immunodeficiency syndrome (AEDS), Addison's disease, adult respiratory distress syndrome, aUergies, ankylosing spondyUtis, amyloidosis, anemia, asthma, atherosclerosis, autoimmune hemolytic anemia, autoimmune thyroiditis, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), bronchitis, cholecystitis, contact dermatitis, Crohn's disease, atopic dermatitis, dermatomyositis, diabetes meUitus, emphysema, episodic lymphopenia with lymphocytotoxins, erythroblastosis fetaUs, erythema nodosum, atrophic gastritis, glomerulonephritis, Goodpasture's syndrome, gout, Graves' disease, Hashimoto's thyroiditis, hypereosinophiUa, irritable bowel syndrome, multiple sclerosis, myasthenia gravis, myocardial or pericardial inflammation, osteoarthritis, osteoporosis, pancreatitis, polymyositis, psoriasis, Reiter' s syndrome, rheumatoid arthritis, scleroderma, Sjogren's syndrome, systemic anaphylaxis, systemic lupus erythematosus, systemic sclerosis, thrombocytopenic purpura, ulcerative coUtis, uveitis, Werner syndrome, compUcations of cancer, hemodialysis, and extracorporeal circulation, viral, bacterial, fungal, parasitic, protozoal, and helminthic infections, and trauma, and an immunodeficiency disorder, such as acquired immunodeficiency syndrome (AEDS), X-Unked agammaglobinemia of Bruton, common variable immunodeficiency (CVE), DiGeorge's syndrome (thymic hypoplasia), thymic dysplasia, isolated IgA deficiency, severe combined immunodeficiency disease (SCID), immunodeficiency with thrombocytopenia and eczema (Wiskott- Aldrich syndrome), Chediak-Higashi syndrome, chronic granulomatous diseases, hereditary angioneurotic edema, and immunodeficiency associated with Cushing's disease.

In another embodiment, a vector capable of expressing GTPB or a fragment or derivative thereof may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of GTPB including, but not Umited to, those described above.

In a further embodiment, a composition comprising a substantiaUy purified GTPB in conjunction with a suitable pharmaceutical earner may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of GTPB including, but not Umited to, those provided above.

In stiU another embodiment, an agonist which modulates the activity of GTPB may be administered to a subject to treat or prevent a disorder associated with decreased expression or activity of GTPB including, but not Umited to, those Usted above.

In a further embodiment, an antagonist of GTPB may be administered to a subject to treat or prevent a disorder associated with increased expression or activity of GTPB. Examples of such disorders include, but are not Umited to, those ceU proUferative, autoimmune/inflammatory, and immunodeficiency disorders described above. In one aspect, an antibody which specificaUy binds GTPB may be used directly as an antagonist or indirectly as a targeting or deUvery mechanism for bringing a pharmaceutical agent to ceUs or tissues which express GTPB.

In an additional embodiment, a vector expressing the complement of the polynucleotide encoding GTPB may be administered to a subject to treat or prevent a disorder associated with increased expression or activity of GTPB including, but not Umited to, those described above. In other embodiments, any of the proteins, antagonists, antibodies, agonists, complementary sequences, or vectors of the invention may be administered in combination with other appropriate therapeutic agents. Selection of the appropriate agents for use in combination therapy may be made by one of ordinary skfil in the art, according to conventional pharmaceutical principles. The combination of therapeutic agents may act synergisticaUy to effect the treatment or prevention of the various disorders described above. Using this approach, one may be able to achieve therapeutic efficacy with lower dosages of each agent, thus reducing the potential for adverse side effects.

An antagonist of GTPB may be produced using methods which are generaUy known in the art. In particular, purified GTPB may be used to produce antibodies or to screen Ubraries of pharmaceutical agents to identify those which specificaUy bind GTPB. Antibodies to GTPB may also be generated using methods that are well known in the art. Such antibodies may include, but are not Umited to, polyclonal, monoclonal, chimeric, and single chain antibodies, Fab fragments, and fragments produced by a Fab expression Ubrary. NeutraUzing antibodies (i.e., those which inhibit dimer formation) are generaUy preferred for therapeutic use.

For the production of antibodies, various hosts including goats, rabbits, rats, mice, humans, and others may be immunized by injection with GTPB or with any fragment or oUgopeptide thereof which has immunogenic properties. Depending on the host species, various adjuvants may be used to increase immunological response. Such adjuvants include, but are not Umited to, Freund's, mineral gels such as aluminum hydroxide, and surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, KLH, and dinitrophenol. Among adjuvants used in humans, BCG (baciUi Calmette-Guerin) and Corvnebacterium parvum are especiaUy preferable.

It is preferred that the oUgopeptides, peptides, or fragments used to induce antibodies to GTPB have an amino acid sequence consisting of at least about 5 amino acids, and generaUy wiU consist of at least about 10 amino acids. It is also preferable that these oUgopeptides, peptides, or fragments are identical to a portion of the amino acid sequence of the natural protein. Short stretches of GTPB amino acids may be fused with those of another protein, such as KLH, and antibodies to the chimeric molecule may be produced.

Monoclonal antibodies to GTPB may be prepared using any technique which provides for the production of antibody molecules by continuous ceU Unes in culture. These include, but are not Umited to, the hybridoma technique, the human B-ceU hybridoma technique, and the EBV-hybridoma technique. (See, e.g., Kohler, G. et al. (1975) Nature 256:495-497; Kozbor, D. et al. (1985) J. Immunol. Methods 81:31-42; Cote, R.J. et al. (1983) Proc. Natl. Acad. Sci. USA 80:2026-2030; and Cole, S.P. et al. (1984) Mol. CeU Biol. 62:109-120.) In addition, techniques developed for the production of "chimeric antibodies," such as the spUcing of mouse antibody genes to human antibody genes to obtain a molecule with appropriate antigen specificity and biological activity, can be used. (See, e.g., Morrison, S.L. et al. (1984) Proc. Natl. Acad. Sci. USA 81:6851-6855; Neuberger, M.S. et al. (1984) Nature 312:604-608; and Takeda, S. et al. (1985) Nature 314:452-454.) Alternatively, techniques described for the production of single chain antibodies may be adapted, using methods known in the art, to produce GTPB-specific single chain antibodies. Antibodies with related specificity, but of distinct idiotypic composition, may be generated by chain shuffling from random combinatorial immunoglobuUn Ubraries. (See, e.g., Burton, D.R. (1991) Proc. Natl. Acad. Sci. USA 88:10134-10137.)

Antibodies may also be produced by inducing in vivo production in the lymphocyte population or by screening immunoglobuUn Ubraries or panels of highly specific binding reagents as disclosed in the Uterature. (See, e.g., Oήmdi, R. et al. (1989) Proc. Natl. Acad. Sci. USA 86:3833-3837; Winter, G. et al. (1991) Nature 349:293-299.)

Antibody fragments which contain specific binding sites for GTPB may also be generated. For example, such fragments include, but are not Umited to, F(ab')₂ fragments produced by pepsin digestion of the antibody molecule and Fab fragments generated by reducing the disulfide bridges of the F(ab')2 fragments. Alternatively, Fab expression Ubraries may be constructed to aUow rapid and easy identification of monoclonal Fab fragments with the desired specificity. (See, e.g., Huse, W.D. et al. (1989) Science 246:1275-1281.)

Various immunoassays may be used for screening to identify antibodies having the desired specificity. Numerous protocols for competitive binding or immunoradiometric assays using either polyclonal or monoclonal antibodies with estabUshed specificities are weU known in the art. Such immunoassays typicaUy involve the measurement of complex formation between GTPB and its specific antibody. A two-site, monoclonal-based immunoassay utilizing monoclonal antibodies reactive to two non-interfering GTPB epitopes is generaUy used, but a competitive binding assay may also be employed (Pound, supra).

Various methods such as Scatchard analysis in conjunction with radioimmunoassay techniques may be used to assess the affinity of antibodies for GTPB. Affinity is expressed as an association constant, K_^, which is defined as the molar concentration of GTPB -antibody complex divided by the molar concentrations of free antigen and free antibody under equiUbrium conditions. The K_^ determined for a preparation of polyclonal antibodies, which are heterogeneous in their affinities for multiple GTPB epitopes, represents the average affinity, or avidity, of the antibodies for GTPB. The K_j determined for a preparation of monoclonal antibodies, which are monospecific for a particular GTPB epitope, represents a true measure of affinity. High-affinity antibody preparations with K_^ ranging from about 10⁹ to 10¹² L/mole are preferred for use in immunoassays in which the GTPB- antibody complex must withstand rigorous manipulations. E-Ow-affinity antibody preparations with JL, ranging from about 10⁶ to 10⁷ L/mole are preferred for use in immunopurification and similar procedures which ultimately require dissociation of GTPB, preferably in active form, from the antibody (Catty, D. (1988) Antibodies, Volume I: A Practical Approach, IRL Press, Washington DC; LiddeU, J.E. and A. Cryer (1991) A Practical Guide to Monoclonal Antibodies, John Wiley & Sons, New York NY).

The liter and avidity of polyclonal antibody preparations may be further evaluated to determine the quaUty and suitabiUty of such preparations for certain downstream appUcations. For example, a polyclonal antibody preparation containing at least 1-2 mg specific antibody/ml, preferably 5-10 mg specific antibody/ml, is generaUy employed in procedures requiring precipitation of GTPB -antibody complexes. Procedures for evaluating antibody specificity, liter, and avidity, and guideUnes for antibody quaUty and usage in various appUcations, are generaUy available. (See, e.g., Catty, supra, and CoUgan et al. supra.) In another embodiment of the invention, the polynucleotides encoding GTPB, or any fragment or complement thereof, may be used for therapeutic purposes. In one aspect, modifications of gene expression can be achieved by designing complementary sequences or antisense molecules (DNA, RNA, PNA, or modified oUgonucleotides) to the coding or regulatory regions of the gene encoding GTPB. Such technology is weU known in the art, and antisense oUgonucleotides or larger fragments can be designed from various locations along the coding or confrol regions of sequences encoding GTPB. (See, e.g., Agrawal, S., ed. (1996) Antisense Therapeutics, Humana Press Inc., Totawa NJ.)

In therapeutic use, any gene deUvery system suitable for introduction of the antisense sequences into appropriate target ceUs can be used. Antisense sequences can be deUvered intraceUularly in the form of an expression plasmid which, upon transcription, produces a sequence complementary to at least a portion of the ceUular sequence encoding the target protein. (See, e.g., Slater, J.E. et al. (1998) J. AUergy CUn. Immunol. 102(3):469-475; and Scanlon, K.J. et al. (1995) 9(13):1288-1296.) Antisense sequences can also be introduced intraceUularly through the use of viral vectors, such as retrovirus and adeno-associated virus vectors. (See, e.g., MiUer, A.D. (1990) Blood 76:271; Ausubel, supra; Uckert, W. and W. Walther (1994) Pharmacol. Ther. 63(3):323-347.) Other gene deUvery mechanisms include Uposome-derived systems, artificial viral envelopes, and other systems known in the art. (See, e.g., Rossi, J.J. (1995) Br. Med. BuU. 51(l):217-225; Boado, R.J. et al. (1998) J. Pharm. Sci. 87(11):1308-1315; and Morris, M.C. et al. (1997) Nucleic Acids Res. 25(14):2730-2736.)

E another embodiment of the invention, polynucleotides encoding GTPB may be used for somatic or germline gene therapy. Gene therapy may be performed to (i) correct a genetic deficiency (e.g., in the cases of severe combined immunodeficiency (SCED)-Xl disease characterized by X- Unked inheritance (Cavazzana-Calvo, M. et al. (2000) Science 288:669-672), severe combined immunodeficiency syndrome associated with an inherited adenosine deaminase (ADA) deficiency (Blaese, R.M. et al. (1995) Science 270:475-480; Bordignon, C. et al. (1995) Science 270:470-475), cystic fibrosis (Zabner, J. et al. (1993) CeU 75:207-216; Crystal, R.G. et al. (1995) Hum. Gene Therapy 6:643-666; Crystal, R.G. et al. (1995) Hum. Gene Therapy 6:667-703), thalassamias, famiUal hypercholesterolemia, and hemophiUa resulting from Factor VUI or Factor IX deficiencies (Crystal, R.G. (1995) Science 270:404-410; Verma, I.M. and N. Somia (1997) Nature 389:239-242)), (ii) express a conditionaUy lethal gene product (e.g., in the case of cancers which result from unregulated ceUproUferation), or (iii) express a protein which affords protection against intracehular parasites (e.g., against human retroviruses, such as human immunodeficiency virus (HIV) (Baltimore, D. (1988) Nature 335:395-396; Poeschla, E. et al. (1996) Proc. Natl. Acad. Sci. USA. 93:11395-11399), hepatitis B or C virus (HBV, HCV); fungal parasites, such as Candida albicans and Paracoccidioides brasiUensis; and protozoan parasites such as Plasmodium falciparum and Trypanosoma cruzi). In the case where a genetic deficiency in GTPB expression or regulation causes disease, the expression of GTPB from an appropriate population of transduced ceUs may alleviate the cUnical manifestations caused by the genetic deficiency. In a further embodiment of the invention, diseases or disorders caused by deficiencies in

GTPB are treated by constructing mammaUan expression vectors encoding GTPB and introducing these vectors by mechanical means into GTPB -deficient ceUs. Mechanical transfer technologies for use with ceUs in vivo or ex vitro include (i) direct DNA microinjection into individual ceUs, (n) ballistic gold particle deUvery, (in) Uposome-mediated transfection, (iv) receptor-mediated gene transfer, and (v) the use of DNA transposons (Morgan, R.A. and W.F. Anderson (1993) Annu. Rev. Biochem. 62:191-217; Ivies, Z. (1997) CeU 91:501-510; Boulay, J-L. and H. Recipon (1998) Curr. Opin. BiotechnoL 9:445-450).

Expression vectors that may be effective for the expression of GTPB include, but are not Umited to, the PCDNA 3.1, EPITAG, PRCCMV2, PREP, PVAX vectors (Invitrogen, Carlsbad CA), PCMV-SCREPT, PCMV-TAG, PEGSH/PERV (Stratagene, La JoUa CA), and PTET-OFF, PTET-ON, PTRE2, PTRE2-LUC, PTK-HYG (Clontech, Palo Alto CA). GTPB may be expressed using (i) a constitutively active promoter, (e.g., from cytomegalovirus (CMV), Rous sarcoma virus (RSV), SV40 virus, thymidine kinase (TK), or β-actin genes), (n) an inducible promoter (e.g., the tetracycUne-regulated promoter (Gossen, M. and H. Bujard (1992) Proc. Natl. Acad. Sci. USA 89:5547-5551; Gossen, M. et al. (1995) Science 268:1766-1769; Rossi, F.M.V. and H.M. Blau (1998) Curr. Opin. BiotechnoL 9:451-456), commerciaUy available in the T-REX plasmid (Invitrogen)); the ecdysone-inducible promoter (available in the plasmids PVGRXR and PESfD; Invitrogen); the FK506/rapamycin inducible promoter; or the RU486/mifepristone inducible promoter (Rossi, F.M.V. and Blau, H.M. supra)), or (in) a tissue-specific promoter or the native promoter of the endogenous gene encoding GTPB from a normal individual.

CommerciaUy available Uposome transformation kits (e.g., the PERFECT LEPED TRANSFECTION KIT, available from Invitrogen) aUow one with ordinary skiU in the art to deUver polynucleotides to target ceUs in culture and require minimal effort to optimize experimental parameters. In the alternative, transformation is performed using the calcium phosphate method (Graham, F.L. and A.J. Eb (1973) Virology 52:456-467), or by electroporation (Neumann, E. et al. (1982) EMBO J. 1 :841-845). The introduction of DNA to primary ceUs requires modification of these standardized mammaUan transfection protocols. In another embodiment of the invention, diseases or disorders caused by genetic defects with respect to GTPB expression are treated by constructing a retrovirus vector consisting of (i) the polynucleotide encoding GTPB under the control of an independent promoter or the retrovirus long terminal repeat (LTR) promoter, (n) appropriate RNA packaging signals, and (in) a Rev-responsive element (RRE) along with additional retrovirus cw-acting RNA sequences and coding sequences required for efficient vector propagation. Retrovirus vectors (e.g., PFB and PFBNEO) are commerciaUy available (Stratagene) and are based on pubUshed data (Riviere, I. et al. (1995) Proc. Natl. Acad. Sci. USA 92:6733-6737), incorporated by reference herein. The vector is propagated in an appropriate vector producing ceU Une (VPCL) that expresses an envelope gene with a fropism for receptors on the target ceUs or a promiscuous envelope protein such as VSVg (Armentano, D. et al. (1987) J. Virol. 61:1647-1650; Bender, M.A. et al. (1987) J. Virol. 61:1639-1646; Adam, M.A. and A.D. MiUer (1988) J. Virol. 62:3802-3806; DuU, T. et al. (1998) J. Virol. 72:8463-8471 ; Zufferey, R. et al. (1998) J. Virol. 72:9873-9880). U.S. Patent Number 5,910,434 to Rigg ("Method for obtaining retrovirus packaging ceU Unes producing high transducing efficiency retroviral supernatant") discloses a method for obtaining retrovirus packaging ceU Unes and is hereby incorporated by reference. Propagation of retrovirus vectors, transduction of a population of ceUs (e.g., CD4⁺ T-ceUs), and the return of transduced ceUs to a patient are procedures weU known to persons skilled in the art of gene therapy and have been weU documented (Ranga, U. et al. (1997) J. Virol. 71:7020-7029; Bauer, G. et al. (1997) Blood 89:2259-2267; Bonyhadi, M.L. (1997) J. Virol. 71:4707-4716; Ranga, U. et al. (1998) Proc. Natl. Acad. Sci. USA 95:1201-1206; Su, L. (1997) Blood 89:2283-2290).

In the alternative, an adenovirus-based gene therapy deUvery system is used to deUver polynucleotides encoding GTPB to ceUs which have one or more genetic abnormaUti.es with respect to the expression of GTPB. The construction and packaging of adenovirus-based vectors are weU known to those with ordinary skiU in the art. RepUcation defective adenovirus vectors have proven to be versatile for importing genes encoding immunoregulatory proteins into intact islets in the pancreas (Csete, M.E. et al. (1995) Transplantation 27:263-268). PotentiaUy useful adenoviral vectors are described in U.S. Patent Number 5,707,618 to Armentano ("Adenovirus vectors for gene therapy"), hereby incorporated by reference. For adenoviral vectors, see also Antinozzi, P. A. et al. (1999) Annu. Rev. Nutr. 19:511-544 and Verma, I.M. and N. Somia (1997) Nature 18:389:239-242, both incorporated by reference herein.

In another alternative, a herpes-based, gene therapy deUvery system is used to deUver polynucleotides encoding GTPB to target ceUs which have one or more genetic abnormaUties with respect to the expression of GTPB. The use of herpes simplex virus (HSV)-based vectors may be especiaUy valuable for introducing GTPB to ceUs of the central nervous system, for which HSV has a tropism. The construction and packaging of herpes-based vectors are weU known to those with ordinary skiU in the art. A repUcation-competent herpes simplex virus (HSV) type 1 -based vector has been used to deUver a reporter gene to the eyes of primates (Liu, X. et al. (1999) Exp. Eye Res. 169:385-395). The construction of a HSV-1 virus vector has also been disclosed in detail in U.S. Patent Number 5,804,413 to DeLuca ("Herpes simplex virus strains for gene transfer"), which is hereby incorporated by reference. U.S. Patent Number 5,804,413 teaches the use of recombinant HSV d92 which consists of a genome containing at least one exogenous gene to be transferred to a ceU under the control of the appropriate promoter for purposes including human gene therapy. Also taught by this patent are the construction and use of recombinant HSV strains deleted for ICP4, ICP27 and ICP22. For HSV vectors, see also Goins, W.F. et al. (1999) J. Virol. 73:519-532 and Xu, H. et al. (1994) Dev. Biol. 163:152-161, hereby incorporated by reference. The manipulation of cloned herpesvirus sequences, the generation of recombinant virus foUowing the transfection of multiple plasmids containing different segments of the large herpesvirus genomes, the growth and propagation of herpesvirus, and the infection of ceUs with herpesvirus are techniques weU known to those of ordinary skiU in the art.

En another alternative, an alphavirus (positive, single-stranded RNA virus) vector is used to deUver polynucleotides encoding GTPB to target ceUs. The biology of the prototypic alphavirus, SemUki Forest Virus (SFV), has been studied extensively and gene transfer vectors have been based on the SFV genome (Garoff, H. and K.-J. Li (1998) Curr. Opin. BiotechnoL 9:464-469). During alphavirus RNA repUcation, a subgenomic RNA is generated that normaUy encodes the viral capsid proteins. This subgenomic RNA repUcates to higher levels than the fuU length genomic RNA, resulting in the overproduction of capsid proteins relative to the viral proteins with enzymatic activity (e.g., protease and polymerase). Similarly, inserting the coding sequence for GTPB into the alphavirus genome in place of the capsid-coding region results in the production of a large number of GTPB- coding RNAs and the synthesis of high levels of GTPB in vector transduced ceUs. While alphavirus infection is typically associated with ceU lysis within a few days, the abiUty to estabUsh a persistent infection in hamster normal kidney ceUs (BHK-21) with a variant of Sindbis virus (SEN) indicates that the lytic repUcation of alphaviruses can be altered to suit the needs of the gene therapy appUcation (Dryga, S.A. et al. (1997) Virology 228:74-83). The wide host range of alphaviruses will allow the introduction of GTPB into a variety of ceU types. The specific transduction of a subset of ceUs in a population may require the sorting of ceUs prior to transduction. The methods of manipulating infectious cDNA clones of alphaviruses, performing alphavirus cDNA and RNA transfections, and performing alphavirus infections, are weU known to those with ordinary skill in the art.

OUgonucleotides derived from the transcription initiation site, e.g., between about positions -10 and +10 from the start site, may also be employed to inhibit gene expression. Similarly, inhibition can be achieved using triple heUx base-pairing methodology. Triple heUx pairing is useful because it causes inhibition of the abiUty of the double heUx to open sufficiently for the binding of polymerases, transcription factors, or regulatory molecules. Recent therapeutic advances using triplex DNA have been described in the Uterature. (See, e.g., Gee, J.E. et al. (1994) in Huber, B.E. and B.I. Carr, Molecular and Imrnunologic Approaches, Futura PubUshing, Mt. Kisco NY, pp. 163-177.) A complementary sequence or antisense molecule may also be designed to block translation of mRNA by preventing the transcript from binding to ribosomes. Ribozymes, enzymatic RNA molecules, may also be used to catalyze the specific cleavage of

RNA. The mechanism of ribozyme action involves sequence-specific hybridization of the ribozyme molecule to complementary target RNA, foUowed by endonucleolytic cleavage. For example, engineered hammerhead motif ribozyme molecules may specificaUy and efficiently catalyze endonucleolytic cleavage of sequences encoding GTPB.

Specific ribozyme cleavage sites within any potential RNA target are initiaUy identified by scanning the target molecule for ribozyme cleavage sites, including the following sequences: GUA, GUU, and GUC. Once identified, short RNA sequences of between 15 and 20 ribonucleotides, corresponding to the region of the target gene containing the cleavage site, may be evaluated for secondary structural features which may render the oUgonucleotide inoperable. The suitability of candidate targets may also be evaluated by testing accessibiUty to hybridization with complementary oUgonucleotides using ribonuclease protection assays.

Complementary ribonucleic acid molecules and ribozymes of the invention may be prepared by any method known in the art for the synthesis of nucleic acid molecules. These include techniques for chemicaUy synthesizing oUgonucleotides such as soUd phase phosphoramidite chemical synthesis. Alternatively, RNA molecules may be generated by in vitro and in vivo franscription of DNA sequences encoding GTPB. Such DNA sequences may be incorporated into a wide variety of vectors with suitable RNA polymerase promoters such as T7 or SP6. Alternatively, these cDNA constructs that synthesize complementaiy RNA, constitutively or inducibly, can be introduced into ceU Unes, ceUs, or tissues.

RNA molecules may be modified to increase intraceUular stabiUty and half-Ufe. Possible modifications include, but are not Umited to, the addition of flanking sequences at the 5' and/or 3' ends ■ of the molecule, or the use of phosphorothioate or 2' O-methyl rather than phosphodiesterase Unkages within the backbone of the molecule. This concept is inherent in the production of PNAs and can be extended in aU of these molecules by the inclusion of nontraditional bases such as inosine, queosine, and wybutosine, as weU as acetyl-, methyl-, thio-, and similarly modified forms of adenine, cytidine, guanine, thymine, and uridine which are not as easily recognized by endogenous endonucleases. An additional embodiment of the invention encompasses a method for screening for a compound which is effective in altering expression of a polynucleotide encoding GTPB. Compounds which may be effective in altering expression of a specific polynucleotide may include, but are not Umited to, oUgonucleotides, antisense oUgonucleotides, triple heUx-forming oUgonucleotides, transcription factors and other polypeptide transcriptional regulators, and non-macromolecular chemical entities which are capable of interacting with specific polynucleotide sequences. Effective compounds may alter polynucleotide expression by acting as either inhibitors or promoters of polynucleotide expression. Thus, in the treatment of disorders associated with increased GTPB expression or activity, a compound which specificaUy inhibits expression of the polynucleotide encoding GTPB may be therapeuticaUy useful, and in the freatment of disorders associated with decreased GTPB expression or activity, a compound which specificaUy promotes expression of the polynucleotide encoding GTPB may be therapeuticaUy useful.

At least one, and up to a pluraUty, of test compounds may be screened for effectiveness in altering expression of a specific polynucleotide. A test compound may be obtained by any method commonly known in the art, including chemical modification of a compound known to be effective in altering polynucleotide expression; selection from an existing, commerciaUy-available or proprietary Ubrary of naturaUy-occurring or non-natural chemical compounds; rational design of a compound based on chemical and/or structural properties of the target polynucleotide; and selection from a Ubrary of chemical compounds created combinatoriaUy or randomly. A sample comprising a polynucleotide encoding GTPB is exposed to at least one test compound thus obtained. The sample may comprise, for example, an intact or permeabiUzed ceU, or an in vitro ceU-free or reconstituted biochemical system. Alterations in the expression of a polynucleotide encoding GTPB are assayed by any method commonly known in the art. TypicaUy, the expression of a specific nucleotide is detected by hybridization with a probe having a nucleotide sequence complementary to the sequence of the polynucleotide encoding GTPB. The amount of hybridization may be quantified, thus forming the basis for a comparison of the expression of the polynucleotide both with and without exposure to one or more test compounds. Detection of a change in the expression of a polynucleotide exposed to a test compound indicates that the test compound is effective in altering the expression of the polynucleotide. A screen for a compound effective in altering expression of a specific polynucleotide can be carried out, for example, using a Schizosaccharomyces pombe gene expression system (Atkins, D. et al. (1999) U.S. Patent No. 5,932,435; Arndt, G.M. et al. (2000) Nucleic Acids Res. 28:E15) or a human ceU Une such as HeLa ceU (Clarke, M.L. et al. (2000) Biochem. Biophys. Res. Commun. 268:8-13). A particular embodiment of the present invention involves screening a combinatorial Ubrary of oUgonucleotides (such as deoxyribonucleotides, ribonucleotides, peptide nucleic acids, and modified oUgonucleotides) for antisense activity against a specific polynucleotide sequence (Bruice, T.W. et al. (1997) U.S. Patent No. 5,686,242; Bruice, T.W. et al. (2000) U.S. Patent No. 6,022,691).

Many methods for introducing vectors into ceUs or tissues are available and equaUy suitable for use in vivo, in vitro, and ex vivo. For ex vivo therapy, vectors may be introduced into stem ceUs taken from the patient and clonaUy propagated for autologous transplant back into that same patient. DeUvery by transfection, by Uposome injections, or by polycatiomc amino polymers may be achieved using methods which are weU known in the art. (See, e.g., Goldman, C.K. et al. (1997) Nat. BiotechnoL 15:462-466.)

Any of the therapeutic methods described above may be appUed to any subject in need of such therapy, including, for example, mammals such as humans, dogs, cats, cows, horses, rabbits, and monkeys.

An additional embodiment of the invention relates to the administration of a composition which generaUy comprises an active ingredient formulated with a pharmaceuticaUy acceptable excipient. Excipients may include, for example, sugars, starches, ceUuloses, gums, and proteins. Various formulations are commonly known and are thoroughly discussed in the latest edition of Remington's Pharmaceutical Sciences (Maack PubUshing, Easton PA). Such compositions may consist of GTPB, antibodies to GTPB, and mimetics, agonists, antagonists, or inhibitors of GTPB.

The compositions utilized in this invention may be administered by any number of routes including, but not Umited to, oral, intravenous, intramuscular, infra-arterial intrameduUary, intrathecal, intraventricular, pulmonary, transdermal, subcutaneous, intraperitoneal, intranasal, enteral, topical, subUngual, or rectal means.

Compositions for pulmonary administration may be prepared in Uquid or dry powder form. These compositions are generaUy aerosoUzed immediately prior to inhalation by the patient. In the case of smaU molecules (e.g. traditional low molecular weight organic drugs), aerosol deUvery of fast- acting formulations is weU-known in the art. In the case of macromolecules (e.g. larger peptides and proteins), recent developments in the field of pulmonary deUvery via the alveolar region of the lung have enabled the practical deUvery of drugs such as insuUn to blood circulation (see, e.g., Patton, J.S. et al, U.S. Patent No. 5,997,848). Pulmonary deUvery has the advantage of administration without needle injection, and obviates the need for potentiaUy toxic penetration enhancers.

Compositions suitable for use in the invention include compositions wherein the active ingredients are contained in an effective amount to achieve the intended purpose. The determination of an effective dose is weU within the capability of those skiUed in the art.

SpeciaUzed forms of compositions may be prepared for direct infraceUular deUvery of macromolecules comprising GTPB or fragments thereof. For example, Uposome preparations containing a ceU-impermeable macromolecule may promote cell fusion and infraceUular deUvery of the macromolecule. Alternatively, GTPB or a fragment thereof may be joined to a short cationic N- terminal portion from the HIV Tat-1 protein. Fusion proteins thus generated have been found to transduce into the ceUs of aU tissues, including the brain, in a mouse model system (Schwarze, S.R. et al. (1999) Science 285:1569-1572).

For any compound, the therapeuticaUy effective dose can be estimated initiaUy either in ceU culture assays, e.g., of neoplastic ceUs, or in animal models such as mice, rats, rabbits, dogs, monkeys, or pigs. An animal model may also be used to determine the appropriate concentration range and route of administration. Such information can then be used to determine useful doses and routes for administration in humans.

A therapeuticaUy effective dose refers to that amount of active ingredient, for example GTPB or fragments thereof, antibodies of GTPB, and agonists, antagonists or inhibitors of GTPB, which ameUorates the symptoms or condition. Therapeutic efficacy and toxicity may be determined by standard pharmaceutical procedures in ceU cultures or with experimental animals, such as by calculating the ED₅₀ (the dose therapeuticaUy effective in 50% of the population) or LD₅₀ (the dose lethal to 50% of the population) statistics. The dose ratio of toxic to therapeutic effects is the therapeutic index, which can be expressed as the LD₅₀ ED₅₀ ratio. Compositions which exhibit large therapeutic indices are preferred. The data obtained from ceU culture assays and animal studies are used to formulate a range of dosage for human use. The dosage contained in such compositions is preferably within a range of circulating concentrations that includes the ED₅₀ with Uttle or no toxicity. The dosage varies within this range depending upon the dosage form employed, the sensitivity of the patient, and the route of administration. The exact dosage wiU be determined by the practitioner, in Ught of factors related to the subject requiring treatment. Dosage and administration are adjusted to provide sufficient levels of the active moiety or to maintain the desired effect. Factors which may be taken into account include the severity of the disease state, the general health of the subject, the age, weight, and gender of the subject, time and frequency of administration, drug combination(s), reaction sensitivities, and response to therapy. Long-acting compositions may be administered every 3 to 4 days, every week, or biweekly depending on the half-Ufe and clearance rate of the particular formulation.

Normal dosage amounts may vary from about 0.1 μg to 100,000 μg, up to a total dose of about 1 gram, depending upon the route of administration. Guidance as to particular dosages and methods of deUvery is provided in the Uterature and generally available to practitioners in the art. Those skilled in the art wiU employ different formulations for nucleotides than for proteins or their inhibitors. Similarly, deUvery of polynucleotides or polypeptides wiU be specific to particular ceUs, conditions, locations, etc. DIAGNOSTICS

In another embodiment, antibodies which specificaUy bind GTPB may be used for the diagnosis of disorders characterized by expression of GTPB, or in assays to monitor patients being treated with GTPB or agonists, antagonists, or inhibitors of GTPB. Antibodies useful for diagnostic purposes may be prepared in the same manner as described above for therapeutics. Diagnostic assays for GTPB include methods which utiUze the antibody and a label to detect GTPB in human body fluids or in extracts of ceUs or tissues. The antibodies may be used with or without modification, and may be labeled by covalent or non-covalent attachment of a reporter molecule. A wide variety of reporter molecules, several of which are described above, are known in the art and may be used.

A variety of protocols for measuring GTPB, including ELISAs, RIAs, and FACS, are known in the art and provide a basis for diagnosing altered or abnormal levels of GTPB expression. Normal or standard values for GTPB expression are estabUshed by combining body fluids or ceU extracts taken from normal mammaUan subjects, for example, human subjects, with antibodies to GTPB under conditions suitable for complex formation. The amount of standard complex formation may be quantitated by various methods, such as photometric means. Quantities of GTPB expressed in subject, control and disease samples from biopsied tissues are compared with the standard values. Deviation between standard and subject values estabUshes the parameters for diagnosing disease.

In another embodiment of the invention, the polynucleotides encoding GTPB may be used for diagnostic purposes. The polynucleotides which may be used include oUgonucleotide sequences, complementary RNA and DNA molecules, and PNAs. The polynucleotides may be used to detect and quantify gene expression in biopsied tissues in which expression of GTPB may be correlated with disease. The diagnostic assay may be used to determine absence, presence, and excess expression of GTPB, and to monitor regulation of GTPB levels during therapeutic intervention.

In one aspect, hybridization with PCR probes which are capable of detecting polynucleotide sequences, including genomic sequences, encoding GTPB or closely related molecules may be used to identify nucleic acid sequences which encode GTPB. The specificity of the probe, whether it is made from a highly specific region, e.g., the 5' regulatory region, or from a less specific region, e.g., a conserved motif, and the stringency of the hybridization or ampUfication wiU determine whether the probe identifies only naturaUy occurring sequences encoding GTPB, alleUc variants, or related sequences. Probes may also be used for the detection of related sequences, and may have at least 50% sequence identity to any of the GTPB encoding sequences. The hybridization probes of the subject invention may be DNA or RNA and may be derived from the sequence of SEQ ED NO:8-14 or from genomic sequences including promoters, enhancers, and introns of the GTPB gene.

Means for producing specific hybridization probes for DNAs encoding GTPB include the cloning of polynucleotide sequences encoding GTPB or GTPB derivatives into vectors for the production of mRNA probes. Such vectors are known in the art, are commerciaUy available, and may be used to synthesize RNA probes in vitro by means of the addition of the appropriate RNA polymerases and the appropriate labeled nucleotides. Hybridization probes may be labeled by a variety of reporter groups, for example, by radionucUdes such as ³²P or ³⁵S, or by enzymatic labels, such as alkaUne phosphatase coupled to the probe via avidin biotin coupUng systems, and the Uke.

Polynucleotide sequences encoding GTPB may be used for the diagnosis of disorders associated with expression of GTPB. Examples of such disorders include, but are not Umited to, a ceU proUferative disorder, such as actinic keratosis, arteriosclerosis, atherosclerosis, bursitis, cirrhosis, hepatitis, mixed connective tissue disease (MCTD), myelofibrosis, paroxysmal nocturnal hemoglobinuria, polycythemia vera, psoriasis, primary thrombocythemia, and cancers including adenocarcinoma, leukemia, lymphoma, melanoma, myeloma, sarcoma, teratocarcinoma, and, in particular, cancers of the adrenal gland, bladder, bone, bone marrow, brain, breast, cervix, gaU bladder, gangUa, gasfrointestinal tract, heart, kidney, Uver, lung, muscle, ovary, pancreas, parathyroid, penis, prostate, saUvary glands, skin, spleen, testis, thymus, thyroid, and uterus, an autoimmune/inflammatory disorder, such as acquired immunodeficiency syndrome (AIDS), Addison's disease, adult respiratory distress syndrome, aUergies, ankylosing spondyUtis, amyloidosis, anemia, asthma, atherosclerosis, autoimmune hemolytic anemia, autoimmune thyroiditis, autoimmune polyendocrinopathy-candidiasis- ectodermal dystrophy (APECED), bronchitis, cholecystitis, contact dermatitis, Crohn's disease, atopic dermatitis, dermatomyositis, diabetes meUitus, emphysema, episodic lymphopenia with lymphocytotoxins, erythroblastosis fetaUs, erythema nodosum, atrophic gastritis, glomerulonephritis, Goodpasture's syndrome, gout, Graves' disease, Hashimoto's thyroiditis, hypereosinophiUa, irritable bowel syndrome, multiple sclerosis, myasthenia gravis, myocardial or pericardial inflammation, osteoarthritis, osteoporosis, pancreatitis, polymyositis, psoriasis, Reiter' s syndrome, rheumatoid arthritis, scleroderma, Sjδgren's syndrome, systemic anaphylaxis, systemic lupus erythematosus, systemic sclerosis, thrombocytopenic purpura, ulcerative coUtis, uveitis, Werner syndrome, compUcations of cancer, hemodialysis, and extracorporeal circulation, viral, bacterial, fungal, parasitic, protozoal, and heUninthic infections, and trauma, and an immunodeficiency disorder, such as acquired immunodeficiency syndrome (AEDS), X-Unked agammaglobinemia of Bruton, common variable immunodeficiency (CVE), DiGeorge's syndrome (thymic hypoplasia), thymic dysplasia, isolated IgA deficiency, severe combined immunodeficiency disease (SOD), immunodeficiency with thrombocytopenia and eczema (Wiskott- Aldrich syndrome), Chediak-Higashi syndrome, chronic granulomatous diseases, hereditary angioneurotic edema, and immunodeficiency associated with Cushing's disease. The polynucleotide sequences encoding GTPB may be used in Southern or northern analysis, dot blot, or other membrane-based technologies; in PCR technologies; in dipstick, pin, and multiformat ELISA-Uke assays; and in microarrays utiUzing fluids or tissues from patients to detect altered GTPB expression. Such quaUtative or quantitative methods are weU known in the ait. In a particular aspect, the nucleotide sequences encoding GTPB may be useful in assays that detect the presence of associated disorders, particularly those mentioned above. The nucleotide sequences encoding GTPB may be labeled by standard methods and added to a fluid or tissue sample from a patient under conditions suitable for the formation of hybridization complexes. After a suitable incubation period, the sample is washed and the signal is quantified and compared with a standard value. If the amount of signal in the patient sample is significantly altered in comparison to a control sample then the presence of altered levels of nucleotide sequences encoding GTPB in the sample indicates the presence of the associated disorder. Such assays may also be used to evaluate the efficacy of a particular therapeutic freatment regimen in animal studies, in cUnical trials, or to monitor the treatment of an individual patient.

In order to provide a basis for the diagnosis of a disorder associated with expression of GTPB, a normal or standard profile for expression is estabUshed. This may be accompUshed by combining body fluids or ceU extracts taken from normal subjects, either animal or human, with a sequence, or a fragment thereof, encoding GTPB, under conditions suitable for hybridization or ampUfication. Standard hybridization may be quantified by comparing the values obtained from normal subjects with values from an experiment in which a known amount of a substantiaUy purified polynucleotide is used. Standard values obtained in this manner may be compared with values obtained from samples from patients who are symptomatic for a disorder. Deviation from standard values is used to estabUsh the presence of a disorder. Once the presence of a disorder is estabUshed and a treatment protocol is initiated, hybridization assays may be repeated on a regular basis to determine if the level of expression in the patient begins to approximate that which is observed in the normal subject. The results obtained from successive assays may be used to show the efficacy of treatment over a period ranging from several days to months. With respect to cancer, the presence of an abnormal amount of transcript (either under- or overexpressed) in biopsied tissue from an individual may indicate a predisposition for the development of the disease, or may provide a means for detecting the disease prior to the appearance of actual clinical symptoms. A more definitive diagnosis of this type may aUow health professionals to employ preventative measures or aggressive freatment earUer thereby preventing the development or further progression of the cancer.

Additional diagnostic uses for oUgonucleotides designed from the sequences encoding GTPB may involve the use of PCR. These oUgomers may be chemicaUy synthesized, generated enzymaticaUy, or produced in vitro. OUgomers wiU preferably contain a fragment of a polynucleotide encoding GTPB, or a fragment of a polynucleotide complementary to the polynucleotide encoding GTPB, and wiU be employed under optimized conditions for identification of a specific gene or condition. OUgomers may also be employed under less stringent conditions for detection or quantification of closely related DNA or RNA sequences. In a particular aspect, oUgonucleotide primers derived from the polynucleotide sequences encoding GTPB may be used to detect single nucleotide polymorphisms (SNPs). SNPs are substitutions, insertions and deletions that are a frequent cause of inherited or acquired genetic disease in humans. Methods of SNP detection include, but are not Umited to, single-stranded conformation polymorphism (SSCP) and fluorescent SSCP (fSSCP) methods. In SSCP, oUgonucleotide primers derived from the polynucleotide sequences encoding GTPB are used to ampUfy DNA using the polymerase chain reaction (PCR). The DNA may be derived, for example, from diseased or normal tissue, biopsy samples, bodily fluids, and the Uke. SNPs in the DNA cause differences in the secondary and tertiary structures of PCR products in single-stranded form, and these differences are detectable using gel electrophoresis in non-denaturing gels. In fSCCP, the oUgonucleotide primers are fluorescently labeled, which aUows detection of the ampUmers in high-throughput equipment such as DNA sequencing machines. AdditionaUy, sequence database analysis methods, termed in siUco SNP (isSNP), are capable of identifying polymorphisms by comparing the sequence of individual overlapping DNA fragments which assemble into a common consensus sequence. These computer- based methods filter out sequence variations due to laboratory preparation of DNA and sequencing errors using statistical models and automated analyses of DNA sequence chromatograms. In the alternative, SNPs may be detected and characterized by mass spectrometry using, for example, the high throughput MASSARRAY system (Sequenom, Inc., San Diego CA).

Methods which may also be used to quantify the expression of GTPB include radiolabeUng or biotinylating nucleotides, coampUfication of a control nucleic acid, and interpolating results from standard curves. (See, e.g., Melby, P.C. et al. (1993) J. Immunol. Methods 159:235-244; Duplaa, C. et al. (1993) Anal. Biochem. 212:229-236.) The speed of quantisation of multiple samples may be accelerated by running the assay in a high-throughput format where the oUgomer or polynucleotide of interest is presented in various dilutions and a spectrophotomefric or colorimetric response gives rapid quantitation. In further embodiments, oUgonucleotides or longer fragments derived from any of the polynucleotide sequences described herein may be used as elements on a microarray. The microarray can be used in transcript imaging techniques which monitor the relative expression levels of large numbers of genes simultaneously as described below. The microarray may also be used to identify genetic variants, mutations, and polymorphisms. This information may be used to determine gene function, to understand the genetic basis of a disorder, to diagnose a disorder, to monitor progression/regression of disease as a function of gene expression, and to develop and monitor the activities of therapeutic agents in the treatment of disease. In particular, this information may be used to develop a pharmacogenomic profile of a patient in order to select the most appropriate and effective freatment regimen for that patient. For example, therapeutic agents which are highly effective and display the fewest side effects may be selected for a patient based on his/her pharmacogenomic profile.

In another embodiment, GTPB, fragments of GTPB, or antibodies specific for GTPB may be used as elements on a microarray. The microarray may be used to monitor or measure protein-protein interactions, drug-target interactions, and gene expression profiles, as described above.

A particular embodiment relates to the use of the polynucleotides of the present invention to generate a transcript image of a tissue or ceU type. A transcript image represents the global pattern of gene expression by a particular tissue or cell type. Global gene expression patterns are analyzed by quantifying the number of expressed genes and their relative abundance under given conditions and at a given time. (See Seilhamer et al, "Comparative Gene Transcript Analysis," U.S. Patent Number 5,840,484, expressly incorporated by reference herein.) Thus a transcript image may be generated by hybridizing the polynucleotides of the present invention or their complements to the totaUty of transcripts or reverse transcripts of a particular tissue or ceU type. In one embodiment, the hybridization takes place in high-throughput format, wherein the polynucleotides of the present invention or their complements comprise a subset of a pluraUty of elements on a microarray. The resultant transcript image would provide a profile of gene activity.

Transcript images may be generated using transcripts isolated from tissues, ceU Unes, biopsies, or other biological samples. The transcript image may thus reflect gene expression in vivo, as in the case of a tissue or biopsy sample, or in vitro, as in the case of a ceU Une.

Transcript images which profile the expression of the polynucleotides of the present invention may also be used in conjunction with in vitro model systems and precUnical evaluation of pharmaceuticals, as weU as toxicological testing of industrial and naturaUy-occurring environmental compounds. AU compounds induce characteristic gene expression patterns, frequently termed molecular fingeφrints or toxicant signatures, which are indicative of mechanisms of action and toxicity (Nuwaysir, E.F. et al. (1999) Mol. Carcinog. 24:153-159; Steiner, S. and N.L. Anderson (2000) Toxicol. Lett. 112-113:467-471, expressly incoφorated by reference herein). If atest compound has a signature similar to that of a compound with known toxicity, it is Ukely to share those toxic properties. These fingeφrints or signatures are most useful and refined when they contain expression information from a large number of genes and gene famiUes. IdeaUy, a genome-wide measurement of expression provides the highest quaUty signature. Even genes whose expression is not altered by any tested compounds are important as weU, as the levels of expression of these genes are used to normaUze the rest of the expression data. The normaUzation procedure is useful for comparison of expression data after treatment with different compounds. While the assignment of gene function to elements of a toxicant signature aids in inteφretation of toxicity mechanisms, knowledge of gene function is not necessary for the statistical matching of signatures which leads to prediction of toxicity. (See, for example, Press Release 00-02 from the National Institute of Environmental Health Sciences, released February 29, 2000, available at http://www.niehs.nih.gov/oc/news/toxchip.htm.) Therefore, it is important and desirable in toxicological screening using toxicant signatures to include aU expressed gene sequences.

In one embodiment, the toxicity of a test compound is assessed by treating a biological sample containing nucleic acids with the test compound. Nucleic acids that are expressed in the treated biological sample are hybridized with one or more probes specific to the polynucleotides of the present invention, so that transcript levels corresponding to the polynucleotides of the present invention may be quantified. The transcript levels in the treated biological sample are compared with levels in an untreated biological sample. Differences in the transcript levels between the two samples are indicative of a toxic response caused by the test compound in the treated sample. Another particular embodiment relates to the use of the polypeptide sequences of the present invention to analyze the proteome of a tissue or ceU type. The term proteome refers to the global pattern of protein expression in a particular tissue or ceU type. Each protein component of a proteome can be subjected individuaUy to further analysis. Proteome expression patterns, or profiles, are analyzed by quantifying the number of expressed proteins and their relative abundance under given conditions and at a given time. A profile of a ceU' s proteome may thus be generated by separating and analyzing the polypeptides of a particular tissue or cell type. In one embodiment, the separation is achieved using two-dimensional gel electrophoresis, in which proteins from a sample are separated by isoelectric focusing in the first dimension, and then according to molecular weight by sodium dodecyl sulfate slab gel electrophoresis in the second dimension (Steiner and Anderson, supra). The proteins are visuaUzed in the gel as discrete and uniquely positioned spots, typicaUy by staining the gel with an agent such as Coomassie Blue or silver or fluorescent stains. The optical density of each protein spot is generaUy proportional to the level of the protein in the sample. The optical densities of equivalently positioned protein spots from different samples, for example, from biological samples either treated or untreated with a test compound or therapeutic agent, are compared to identify any changes in protein spot density related to the freatment. The proteins in the spots are partiaUy sequenced using, for example, standard methods employing chemical or enzymatic cleavage foUowed by mass spectrometry. The identity of the protein in a spot may be determined by comparing its partial sequence, preferably of at least 5 contiguous amino acid residues, to the polypeptide sequences of the present invention. In some cases, further sequence data may be obtained for definitive protein identification.

A proteomic profile may also be generated using antibodies specific for GTPB to quantify the levels of GTPB expression. In one embodiment, the antibodies are used as elements on a microarray, and protein expression levels are quantified by exposing the microarray to the sample and detecting the levels of protein bound to each array element (Lueking, A. et al. (1999) Anal. Biochem. 270:103- 111; Mendoze, L.G. et al. (1999) Biotechniques 27:778-788). Detection may be performed by a variety of methods known in the art, for example, by reacting the proteins in the sample with a thiol- or amino-reactive fluorescent compound and detecting the amount of fluorescence bound at each array element.

Toxicant signatures at the proteome level are also useful for toxicological screening, and should be analyzed in paraUel with toxicant signatures at the transcript level. There is a poor correlation between transcript and protein abundances for some proteins in some tissues (Anderson, N.L. and J. Seilhamer (1997) Electrophoresis 18:533-537), so proteome toxicant signatures may be useful in the analysis of compounds which do not significantly affect the transcript image, but which alter the proteomic profile. In addition, the analysis of transcripts in body fluids is difficult, due to rapid degradation of mRNA, so proteomic profiling may be more reUable and informative in such cases.

In another embodiment, the toxicity of a test compound is assessed by treating a biological sample containing proteins with the test compound. Proteins that are expressed in the treated biological sample are separated so that the amount of each protein can be quantified. The amount of each protein is compared to the amount of the corresponding protein in an untreated biological sample. A difference in the amount of protein between the two samples is indicative of a toxic response to the test compound in the treated sample. Individual proteins are identified by sequencing the amino acid residues of the individual proteins and comparing these partial sequences to the polypeptides of the present invention.

In another embodiment, the toxicity of a test compound is assessed by treating a biological sample containing proteins with the test compound. Proteins from the biological sample are incubated with antibodies specific to the polypeptides of the present invention. The amount of protein recognized by the antibodies is quantified. The amount of protein in the treated biological sample is compared with the amount in an untreated biological sample. A difference in the amount of protein between the two samples is indicative of a toxic response to the test compound in the treated sample.

Microarrays may be prepared, used, and analyzed using methods known in the ait. (See, e.g., Brennan, T.M. et al. (1995) U.S. Patent No. 5,474,796; Schena, M. et al. (1996) Proc. Natl. Acad. Sci. USA 93:10614-10619; Baldeschweiler et al. (1995) PCT appUcation W095/251116; Shalon, D. et al. (1995) PCT appUcation WO95/35505; HeUer, R.A. et al. (1997) Proc. Natl. Acad. Sci. USA 94:2150-2155; and HeUer, M.J. et al. (1997) U.S. Patent No. 5,605,662.) Various types of microarrays are well known and thoroughly described in DNA Microarrays: A Practical Approach, M. Schena, ed. (1999) Oxford University Press, London, hereby expressly incoφorated by reference.

In another embodiment of the invention, nucleic acid sequences encoding GTPB may be used to generate hybridization probes useful in mapping the naturaUy occurring genomic sequence. Either coding or noncoding sequences may be used, and in some instances, noncoding sequences may be preferable over coding sequences. For example, conservation of a coding sequence among members of a multi-gene family may potentiaUy cause undesired cross hybridization during chromosomal mapping. The sequences may be mapped to a particular chromosome, to a specific region of a chromosome, or to artificial chromosome constructions, e.g., human artificial chromosomes (HACs), . yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs), bacterial PI constructions, or single chromosome cDNA Ubraries. (See, e.g., Harrington, J.J. et al. (1997) Nat. Genet. 15:345-355; Price, CM. (1993) Blood Rev. 7.T27-134; and Trask, B J. (1991) Trends Genet. 7:149-154.) Once mapped, the nucleic acid sequences of the invention may be used to develop genetic Unkage maps, for example, which correlate the inheritance of a disease state with the inheritance of a particular chromosome region or restriction fragment length polymoiphism (RFLP). (See, for example, Lander, E.S. and D. Botstein (1986) Proc. Natl. Acad. Sci. USA 83:7353-7357.) Fluorescent in situ hybridization (FISH) may be correlated with other physical and genetic map data. (See, e.g., Heinz-Ulrich, et al. (1995) in Meyers, supra, pp. 965-968.) Examples of genetic map data can be found in various scientific journals or at the Online MendeUan Inheritance in Man (OMEM) World Wide Web site. Correlation between the location of the gene encoding GTPB on a physical map and a specific disorder, or a predisposition to a specific disorder, may help define the region of DNA associated with that disorder and thus may further positional cloning efforts.

In situ hybridization of chromosomal preparations and physical mapping techniques, such as Unkage analysis using estabUshed chromosomal markers, may be used for extending genetic maps. Often the placement of a gene on the chromosome of another mammaUan species, such as mouse, may reveal associated markers even if the exact chromosomal locus is not known. This information is valuable to investigators searching for disease genes using positional cloning or other gene discovery techniques. Once the gene or genes responsible for a disease or syndrome have been crudely locaUzed by genetic Unkage to a particular genomic region, e.g., ataxia-telangiectasia to 1 lq22-23, any sequences mapping to that area may represent associated or regulatory genes for fuither investigation. (See, e.g., Gatti, R.A. et al. (1988) Nature 336:577-580.) The nucleotide sequence of the instant invention may also be used to detect differences in the chromosomal location due to franslocation, inversion, etc., among normal, carrier, or affected individuals.

In another embodiment of the invention, GTPB, its catalytic or immunogenic fragments, or oUgopeptides thereof can be used for screening Ubraries of compounds in any of a variety of drag screening techniques. The fragment employed in such screening may be free in solution, affixed to a soUd support, borne on a ceU surface, or located intraceUularly. The formation of binding complexes between GTPB and the agent being tested may be measured.

Another technique for drag screening provides for high throughput screening of compounds having suitable binding affinity to the protein of interest. (See, e.g., Geysen, et al. (1984) PCT appUcation WO84/03564.) In this method, large numbers of different smaU test compounds are synthesized on a soUd substrate. The test compounds are reacted with GTPB, or fragments thereof, and washed. Bound GTPB is then detected by methods weU known in the art. Purified GTPB can also be coated directly onto plates for use in the aforementioned drag screening techniques. Alternatively, non-neufraUzing antibodies can be used to capture the peptide and immobiUze it on a soUd support.

In another embodiment, one may use competitive drug screening assays in which neutraUzing antibodies capable of binding GTPB specificaUy compete with a test compound for binding GTPB. In this manner, antibodies can be used to detect the presence of any peptide which shares one or more antigenic determinants with GTPB.

In additional embodiments, the nucleotide sequences which encode GTPB may be used in any molecular biology techniques that have yet to be developed, provided the new techniques rely on properties of nucleotide sequences that are currently known, including, but not Umited to, such properties as the triplet genetic code and specific base pair interactions. Without further elaboration, it is beUeved that one skiUed in the art can, using the preceding description, utiUze the present invention to its fullest extent. The foUowing embodiments are, therefore, to be construed as merely iUusfrative, and not Umitative of the remainder of the disclosure in any way whatsoever. The disclosures of aU patents, appUcations and pubUcations, mentioned above and below, including U.S. Ser. No. 60/216,795, are expressly incoφorated by reference herein.

EXAMPLES I. Construction of cDNA Libraries

Incyte cDNAs were derived from cDNA Ubraries described in the LEFESEQ GOLD database (Encyte Genomics, Palo Alto CA) and shown in Table 4, column 5. Some tissues were homogenized and lysed in guanidinium isothiocyanate, while others were homogenized and lysed in phenol or in a suitable mixture of denaturants, such as TRIZOL (Life Technologies), a monophasic solution of phenol and guanidine isothiocyanate. The resulting lysates were centrifuged over CsCl cushions or extracted with chloroform. RNA was precipitated from the lysates with either isopropanol or sodium acetate and ethanol, or by other routine methods.

Phenol extraction and precipitation of RNA were repeated as necessary to increase RNA purity. In some cases, RNA was treated with DNase. For most Ubraries, poly(A)+ RNA was isolated using oUgo d(T)-coupled paramagnetic particles (Promega), OLIGOTEX latex particles (QIAGEN, Chatsworth CA), or an OLIGOTEX mRNA purification kit (QIAGEN). Alternatively, RNA was isolated directly from tissue lysates using other RNA isolation kits, e.g., the POLY(A)PURE mRNA purification kit (Ambion, Austin TX).

In some cases, Stratagene was provided with RNA and constructed the corresponding cDNA Ubraries. Otherwise, cDNA was synthesized and cDNA Ubraries were constructed with the

UNEZAP vector system (Sfratagene) or SUPERSCRIPT plasmid system (Life Technologies), using the recommended procedures or similar methods known in the ait. (See, e.g., Ausubel, 1997, supra, units 5.1-6.6.) Reverse transcription was initiated using oUgo d(T) or random primers. Synthetic oUgonucleotide adapters were Ugated to double stranded cDNA, and the cDNA was digested with the appropriate restriction enzyme or enzymes. For most Ubraries, the cDNA was size-selected (300- 1000 bp) using SEPHACRYL S1000, SEPHAROSE CL2B, or SEPHAROSE CL4B column chromatography (Amersham Pharmacia Biotech) or preparative agarose gel electrophoresis. cDNAs were Ugated into compatible restriction enzyme sites of the polyUnker of a suitable plasmid, e.g., PBLUESCREPT plasmid (Sfratagene), PSPORT1 plasmid (Life Technologies), PCDNA2.1 plasmid (Invifrogen, Carlsbad CA), PBK-CMV plasmid (Sfratagene), or pENCY (Incyte Genomics, Palo Alto CA), or derivatives thereof. Recombinant plasmids were transformed into competent E. coU ceUs including XLl-Blue, XLl-BlueMRF, or SOLR from Stratagene or DH5α, DH10B, or ElectroMAX DH10B from Life Technologies. II. Isolation of cDNA Clones

Plasmids obtained as described in Example I were recovered from host ceUs by in vivo excision using the UNIZAP vector system (Stratagene) or by ceU lysis. Plasmids were purified using at least one of the foUowing: a Magic or WIZARD Minipreps DNA purification system (Promega); an AGTC Miniprep purification kit (Edge Biosystems, Gaithersburg MD); and QIAWELL 8 Plasmid, QIAWELL 8 Plus Plasmid, QIAWELL 8 Ultra Plasmid purification systems or the R.E.A.L. PREP 96 plasmid purification kit from QEAGEN. FoUowing precipitation, plasmids were resuspended in 0.1 ml of distiUed water and stored, with or without lyophiUzation, at 4°C

Alternatively, plasmid DNA was ampUfied from host ceU lysates using direct Unk PCR in a high-throughput format (Rao, NB. (1994) Anal. Biochem. 216:1-14). Host ceU lysis and thermal cycUng steps were carried out in a single reaction mixture. Samples were processed and stored in 384-weU plates, and the concentration of ampUfied plasmid DΝA was quantified fluoromefricaUy using PICOGREEΝ dye (Molecular Probes, Eugene OR) and a FLUOROSKAΝ H fluorescence scanner (Labsystems Oy, Helsinki, Finland). III. Sequencing and Analysis

Incyte cDΝA recovered in plasmids as described in Example EC were sequenced as foUows. Sequencing reactions were processed using standard methods or high-throughput instrumentation such as the ABI CATALYST 800 (AppUed Biosystems) thermal cycler or the PTC-200 thermal cycler (MJ Research) in conjunction with the HYDRA microdispenser (Robbins Scientific) or the MICROLAB 2200 (Hamilton) Hquid transfer system. cDΝA sequencing reactions were prepared using reagents provided by Amersham Pharmacia Biotech or suppUed in ABI sequencing kits such as the ABI PRISM BIGDYE Terminator cycle sequencing ready reaction kit (AppUed Biosystems). Electrophoretic separation of cDΝA sequencing reactions and detection of labeled polynucleotides were carried out using the MEGABACE 1000 DΝA sequencing system (Molecular Dynamics); the ABI PRISM 373 or 377 sequencing system (AppUed Biosystems) in conjunction with standard ABI protocols and base calling software; or other sequence analysis systems known in the art. Reading frames within the cDΝA sequences were identified using standard methods (reviewed in Ausubel, 1997, supra, unit 7.7). Some of the cDΝA sequences were selected for extension using the techniques disclosed in Example VUI. The polynucleotide sequences derived from Incyte cDΝAs were vaUdated by removing vector, Unker, and poly(A) sequences and by masking ambiguous bases, using algorithms and programs based on BLAST, dynamic programming, and dinucleotide nearest neighbor analysis. The Incyte cDΝA sequences or translations thereof were then queried against a selection of pubUc databases such as the GenBank primate, rodent, mammaUan, vertebrate, and eukaryote databases, and BLOCKS, PRINTS, DOMO, PRODOM, and hidden Markov model (HMM)-based protein family databases such as PFAM. (HMM is a probabiUstic approach which analyzes consensus primaiy structures of gene families. See, for example, Eddy, S.R. (1996) Curr. Opin. Struct. Biol. 6:361-365.) The queries were performed using programs based on BLAST, FASTA, BLIMPS, and HMMER. The Incyte cDNA sequences were assembled to produce full length polynucleotide sequences. Alternatively, GenBank cDNAs, GenBank ESTs, stitched sequences, stretched sequences, or Genscan-predicted coding sequences (see Examples IN and V) were used to extend Incyte cDΝA assemblages to fuU length. Assembly was performed using programs based on Phred, Phrap, and Consed, and cDΝA assemblages were screened for open reading frames using programs based on GeneMark, BLAST, and FASTA. The fuU length polynucleotide sequences were translated to derive the corresponding fuU length polypeptide sequences. Alternatively, a polypeptide of the invention may begin at any of the methionine residues of the fuU length franslated polypeptide. FuU length polypeptide sequences were subsequently analyzed by querying against databases such as the GenBank protein databases (genpept), SwissProt, BLOCKS, PRINTS, DOMO, PRODOM, Prosite, and hidden Markov model (HMM)-based protein family databases such as PFAM. FuU length polynucleotide sequences are also analyzed using MACDNASIS PRO software (Hitachi Software Engineering, South San Francisco CA) and LASERGENE software (DNASTAR). Polynucleotide and polypeptide sequence aUgnments are generated using default parameters specified by the CLUSTAL algorithm as incoφorated into the MEGALIGN multisequence aUgnment program (DNASTAR), which also calculates the percent identity between aUgned sequences.

Table 7 summarizes the tools, programs, and algorithms used for the analysis and assembly of Incyte cDNA and fuU length sequences and provides appUcable descriptions, references, and threshold parameters. The first column of Table 7 shows the tools, programs, and algorithms used, the second column provides brief descriptions thereof, the third column presents appropriate references, aU of which are incoφorated by reference herein in their entirety, and the fourth column presents, where appUcable, the scores, probabiUty values, and other parameters used to evaluate the strength of a match between two sequences (the higher the score or the lower the probabiUty value, the greater the identity between two sequences). The programs described above for the assembly and analysis of full length polynucleotide and polypeptide sequences were also used to identify polynucleotide sequence fragments from SEQ JD NO:8-14. Fragments from about 20 to about 4000 nucleotides which are useful in hybridization and ampUfication technologies are described in Table 4, column 4. IV. Identification and Editing of Coding Sequences from Genomic DNA

Putative GTP-binding proteins were initiaUy identified by running the Genscan gene identification program against pubUc genomic sequence databases (e.g., gbpri and gbhtg). Genscan is a general-p pose gene identification program which analyzes genomic DNA sequences from a variety of organisms (See Burge, C and S. KarUn (1997) J. Mol. Biol. 268:78-94, and Burge, C. and S. KarUn (1998) Curr. Opin. Struct. Biol. 8:346-354). The program concatenates predicted exons to form an assembled cDNA sequence extending from a methionine to a stop codon. The output of Genscan is a FASTA database of polynucleotide and polypeptide sequences. The maximum range of sequence for Genscan to analyze at once was set to 30 kb. To determine which of these Genscan predicted cDNA sequences encode GTP-binding proteins, the encoded polypeptides were analyzed by querying against PFAM models for GTP-binding proteins. Potential GTP-binding proteins were also identified by homology to Incyte cDNA sequences that had been annotated as GTP-binding proteins. These selected Genscan-predicted sequences were then compared by BLAST analysis to the genpept and gbpri pubUc databases. Where necessary, the Genscan-predicted sequences were then edited by comparison to the top BLAST hit from genpept to correct errors in the sequence predicted by

Genscan, such as extra or omitted exons. BLAST analysis was also used to find any Incyte cDNA or pubUc cDNA coverage of the Genscan-predicted sequences, thus providing evidence for transcription. When Incyte cDNA coverage was available, this information was used to correct or confirm the Genscan predicted sequence. FuU length polynucleotide sequences were obtained by assembUng Genscan-predicted coding sequences with Incyte cDNA sequences and/or pubUc cDNA sequences using the assembly process described in Example HI. Alternatively, fuU length polynucleotide sequences were derived entirely from edited or unedited Genscan-predicted coding sequences.

V. Assembly of Genomic Sequence Data with cDNA Sequence Data "Stitched" Sequences Partial cDNA sequences were extended with exons predicted by the Genscan gene identification program described in Example TV. Partial cDNAs assembled as described in Example EH were mapped to genomic DNA and parsed into clusters containing related cDNAs and Genscan exon predictions from one or more genomic sequences. Each cluster was analyzed using an algorithm based on graph theory and dynamic programming to integrate cDNA and genomic information, generating possible spUce variants that were subsequently confirmed, edited, or extended to create a fuU length sequence. Sequence intervals in wliich the entire length of the interval was present on more than one sequence in the cluster were identified, and intervals thus identified were considered to be equivalent by transitivity. For example, if an interval was present on a cDNA and two genomic sequences, then aU three intervals were considered to be equivalent. This process aUows unrelated but consecutive genomic sequences to be brought together, bridged by cDNA sequence. Intervals thus identified were then "stitched" together by the stitching algorithm in the order that they appear along their parent sequences to generate the longest possible sequence, as weU as sequence variants. Linkages between intervals wliich proceed along one type of parent sequence (cDNA to cDNA or genomic sequence to genomic sequence) were given preference over Unkages which change parent type (cDNA to genomic sequence). The resultant stitched sequences were translated and compared by BLAST analysis to the genpept and gbpri pubUc databases. Incorrect exons predicted by Genscan were corrected by comparison to the top BLAST hit from genpept. Sequences were further extended with additional cDNA sequences, or by inspection of genomic DNA, when necessary. "Stretched" Sequences

Partial DNA sequences were extended to fuU length with an algorithm based on BLAST analysis. First, partial cDNAs assembled as described in Example HI were queried against pubUc databases such as the GenBank primate, rodent, mammaUan, vertebrate, and eukaryote databases using the BLAST program. The nearest GenBank protein homolog was then compared by BLAST analysis to either Incyte cDNA sequences or GenScan exon predicted sequences described in Example TV. A chimeric protein was generated by using the resultant high-scoring segment pairs (HSPs) to map the translated sequences onto the GenB ank protein homolog. Insertions or deletions may occur in the chimeric protein with respect to the original GenBank protein homolog. The GenBank protein homolog, the chimeric protein, or both were used as probes to search for homologous genomic sequences from the pubUc human genome databases. Partial DNA sequences were therefore "stretched" or extended by the addition of homologous genomic sequences. The resultant stretched sequences were examined to determine whether it contained a complete gene. VI. Chromosomal Mapping of GTPB Encoding Polynucleotides The sequences wliich were used to assemble SEQ ID NO:8-14 were compared with sequences from the Incyte LEFESEQ database and pubUc domain databases using BLAST and other implementations of the Smith- Waterman algorithm. Sequences from these databases that matched SEQ ED NO:8-14 were assembled into clusters of contiguous and overlapping sequences using assembly algorithms such as Phrap (Table 7). Radiation hybrid and genetic mapping data available from pubUc resources such as the Stanford Human Genome Center (SHGC), Whitehead Institute for Genome Research (WIGR), and Genethon were used to determine if any of the clustered sequences had been previously mapped. Inclusion of a mapped sequence in a cluster resulted in the assignment of aU sequences of that cluster, including its particular SEQ ID NO:, to that map location. Map locations are represented by ranges, or intervals, of human chromosomes. The map position of an interval, in centiMorgans, is measured relative to the terminus of the chromosome's p- arm. (The centiMorgan (cM) is a unit of measurement based on recombination frequencies between chromosomal markers. On average, 1 cM is roughly equivalent to 1 megabase (Mb) of DNA in humans, although this can vary widely due to hot and cold spots of recombination.) The cM distances are based on genetic markers mapped by Genethon which provide boundaries for radiation hybrid markers whose sequences were included in each of the clusters. Human genome maps and other resources available to the pubUc, such as the NCBI "GeneMap'99" World Wide Web site (htφ://www.ncbi.nlm.nih.gov/genemap/), can be employed to determine if previously identified disease genes map within or in proximity to the intervals indicated above.

In this manner, SEQ ED NO:8 was mapped to chromosome 3 within the interval from 142.20 to 148.70 centiMorgans, and to chromosome 10 within the interval from 28.90 to 32.00 centiMorgans. SEQ ID NO:14 was mapped to chromosome 10 within the intervals from 81.70 to 83.30 centiMorgans and from 75.40 to 84.90 centiMorgans. More than one map location is reported for SEQ ED NO:8, indicating that sequences having different map locations were assembled into a single cluster. This situation occurs, for example, when sequences having strong similarity, but not complete identity, are assembled into a single cluster. VII. Analysis of Polynucleotide Expression

Northern analysis is a laboratory technique used to detect the presence of a transcript of a gene and involves the hybridization of a labeled nucleotide sequence to a membrane on which RNAs from a particular ceU type or tissue have been bound. (See, e.g., Sambrook, supra, ch. 7; Ausubel (1995) supra, ch. 4 and 16.)

Analogous computer techniques applying BLAST were used to search for identical or related molecules in cDNA databases such as GenBank or LEFESEQ (Incyte Genomics). This analysis is much faster than multiple membrane-based hybridizations. In addition, the sensitivity of the computer search can be modified to determine whether any particular match is categorized as exact or similar. The basis of the search is the product score, which is defined as:

BLAST Score x Percent Identity 5 x minimum {length(Seq. 1), length(Seq. 2) }

The product score takes into account both the degree of similarity between two sequences and the length of the sequence match. The product score is a normaUzed value between 0 and 100, and is calculated as foUows: the BLAST score is multipUed by the percent nucleotide identity and the product is divided by (5 times the length of the shorter of the two sequences). The BLAST score is calculated by assigning a score of +5 for every base that matches in a high-scoring segment pair (HSP), and -4 for every mismatch. Two sequences may share more than one HSP (separated by gaps) . If there is more than one HSP, then the pair with the highest BLAST score is used to calculate the product score. The product score represents a balance between fractional overlap and quaUty in a BLAST aUgnment. For example, a product score of 100 is produced only for 100% identity over the entire length of the shorter of the two sequences being compared. A product score of 70 is produced either by 100% identity and 70% overlap at one end, or by 88% identity and 100% overlap at the other. A product score of 50 is produced either by 100% identity and 50% overlap at one end, or 79% identity and 100% overlap.

Alternatively, polynucleotide sequences encoding GTPB are analyzed with respect to the tissue sources from which they were derived. For example, some full length sequences are assembled, at least in part, with overlapping Incyte cDNA sequences (see Example HE). Each cDNA sequence is derived from a cDNA Ubrary constructed from a human tissue. Each human tissue is classified into one of the following organ/tissue categories: cardiovascular system; connective tissue; ' digestive system; embryonic structures; endocrine system; exocrine glands; genitaUa, female; genitaUa, male; germ ceUs; hemic and immune system; Uver; musculoskeletal system; nervous system; pancreas; respiratory system; sense organs; skin; stomatognathic system; unclassified/mixed; or urinary tract. The number of Ubraries in each category is counted and divided by the total number of Ubraries across aU categories. Similarly, each human tissue is classified into one of the foUowing disease/condition categories: cancer, ceU Une, developmental, inflammation, neurological, trauma, cardiovascular, pooled, and other, and the number of Ubraries in each category is counted and divided by the total number of Ubraries across aU categories. The resulting percentages reflect the tissue- and disease-specific expression of cDNA encoding GTPB. cDNA sequences and cDNA Ubrary/tissue information are found in the LIFESEQ GOLD database (Incyte Genomics, Palo Alto CA). VIII. Extension of GTPB Encoding Polynucleotides

FuU length polynucleotide sequences were also produced by extension of an appropriate fragment of the fuU length molecule using oUgonucleotide primers designed from this fragment. One primer was synthesized to initiate 5' extension of the known fragment, and the other primer was synthesized to initiate 3' extension of the known fragment. The initial primers were designed using OLIGO 4.06 software (National Biosciences), or another appropriate program, to be about 22 to 30 nucleotides in length, to have a GC content of about 50% or more, and to anneal to the target sequence at temperatures of about 68 °C to about 72 °C. Any stretch of nucleotides which would result in haiφin structures and primer-primer dimerizations was avoided.

Selected human cDNA Ubraries were used to extend the sequence. If more than one extension was necessary or desired, additional or nested sets of primers were designed. High fideUty ampUfication was obtained by PCR using methods weU known in the art. PCR was performed in 96-weU plates using the PTC-200 thermal cycler (MJ Research, Inc.). The reaction mix contained DNA template, 200 nmol of each primer, reaction buffer containing Mg²⁺, (NH₄)₂S0₄, and 2-mercaptoethanol, Taq DNA polymerase (Amersham Pharmacia Biotech), ELONGASE enzyme (Life Technologies), and Pfu DNA polymerase (Stratagene), with the following parameters for primer pair PCI A and PCI B: Step 1 : 94°C, 3 min; Step 2: 94°C, 15 sec; Step 3: 60°C, 1 min; Step 4: 68 °C, 2 min; Step 5: Steps 2, 3, and 4 repeated 20 times; Step 6: 68 °C, 5 min; Step 7: storage at 4°C In the alternative, the parameters for primer pair T7 and SK+ were as foUows: Step 1 : 94°C, 3 min; Step 2: 94°C, 15 sec; Step 3: 57°C, 1 min; Step 4: 68°C, 2 min; Step 5: Steps 2, 3, and 4 repeated 20 times; Step 6: 68°C, 5 min; Step 7: storage at 4°C The concentration of DNA in each weU was determined by dispensing 100 μl PICOGREEN quantisation reagent (0.25% (v/v) PICOGREEN; Molecular Probes, Eugene OR) dissolved in IX TE and 0.5 μl of undiluted PCR product into each well of an opaque fluorimeter plate (Corning Costar, Acton MA), aUowing the DNA to bind to the reagent. The plate was scanned in a Fluoroskan π (Labsystems Oy, Helsinki, Finland) to measure the fluorescence of the sample and to quantify the concentration of DNA. A 5 μl to 10 μl aUquot of the reaction mixture was analyzed by electrophoresis on a 1 % agarose gel to determine which reactions were successful in extending the sequence.

The extended nucleotides were desalted and concentrated, transferred to 384-weU plates, digested with CviJI cholera virus endonuclease (Molecular Biology Research, Madison WE), and sonicated or sheared prior to reUgation into pUC 18 vector (Amersham Pharmacia Biotech). For shotgun sequencing, the digested nucleotides were separated on low concentration (0.6 to 0.8%) agarose gels, fragments were excised, and agar digested with Agar ACE (Promega). Extended clones were reUgated using T4 Ugase (New England Biolabs, Beverly MA) into pUC 18 vector (Amersham Pharmacia Biotech), treated with Pfu DNA polymerase (Stratagene) to fiU-in restriction site overhangs, and transfected into competent E. coU ceUs. Transformed ceUs were selected on antibiotic-containing media, and individual colonies were picked and cultured overnight at 37 °C in 384- weU plates in LB/2x carb Uquid media.

The ceUs were lysed, and DNA was ampUfied by PCR using Taq DNA polymerase (Amersham Pharmacia Biotech) and Pfu DNA polymerase (Stratagene) with the foUowing parameters: Step 1: 94°C, 3 min; Step 2: 94°C, 15 sec; Step 3: 60°C, 1 min; Step 4: 72°C, 2 min; Step 5: steps 2, 3, and 4 repeated 29 times; Step 6: 72 °C, 5 min; Step 7: storage at 4°C DNA was quantified by PICOGREEN reagent (Molecular Probes) as described above. Samples with low DNA recoveries were reampUfied using the same conditions as described above. Samples were diluted with 20% dimethysuUoxide (1:2, v/v), and sequenced using DYENAMIC energy transfer sequencing primers and the DYENAMIC DIRECT kit (Amersham Pharmacia Biotech) or the ABI PRISM BIGDYE Terminator cycle sequencing ready reaction kit (AppUed Biosystems).

In Uke manner, fuU length polynucleotide sequences are verified using the above procedure or are used to obtain 5' regulatory sequences using the above procedure along with oUgonucleotides designed for such extension, and an appropriate genomic Ubrary. IX. Labeling and Use of Individual Hybridization Probes

Hybridization probes derived from SEQ ED NO:8-14 are employed to screen cDNAs, genomic DNAs, or mRNAs. Although the labeUng of oUgonucleotides, consisting of about 20 base pairs, is specificaUy described, essentiaUy the same procedure is used with larger nucleotide fragments. OUgonucleotides are designed using state-of-the-art software such as OLIGO 4.06 software (National Biosciences) and labeled by combining 50 pmol of each oUgomer, 250 Ci of [γ_³²pj adenosine triphosphate (Amersham Pharmacia Biotech), and T4 polynucleotide kinase (DuPont NEN, Boston MA). The labeled oUgonucleotides are substantiaUy purified using a SEPHADEX G-25 superfine size exclusion dextran bead column (Amersham Pharmacia. Biotech). An aUquot containing 10⁷ counts per minute of the labeled probe is used in a typical membrane-based hybridization analysis of human genomic DNA digested with one of the foUowing endonucleases: Ase I, Bgl π, Eco RI, Pst I, Xba I, or Pvu E (DuPont NEN).

The DNA from each digest is fractionated on a 0.7% agarose gel and transferred to nylon membranes (Nytran Plus, Schleicher & SchueU, Durham NH). Hybridization is carried out for 16 hours at 40 °C. To remove nonspecific signals, blots are sequentiaUy washed at room temperature under conditions of up to, for example, 0.1 x saUne sodium citrate and 0.5% sodium dodecyl sulfate. Hybridization patterns are visuaUzed using autoradiography or an alternative imaging means and compared. X. Microarrays

The Unkage or synthesis of array elements upon a microarray can be achieved utilizing photoUthography, piezoelectric printing (ink-jet printing, See, e.g., Baldeschweiler, supra.), mechanical microspotting technologies, and derivatives thereof. The substrate in each of the aforementioned technologies should be uniform and soUd with a non-porous surface (Schena (1999), supra). Suggested substrates include siUcon, siUca, glass sUdes, glass chips, and siUcon wafers. Alternatively, a procedure analogous to a dot or slot blot may also be used to arrange and Unk elements to the surface of a substrate using thermal, UN chemical, or mechanical bonding procedures. A typical array may be produced using available methods and machines weU known to those of ordinary skiU in the art and may contain any appropriate number of elements. (See, e.g., Schena, M. et al. (1995) Science 270:467-470; Shalon, D. et al. (1996) Genome Res. 6:639-645; MarshaU, A. and J. Hodgson (1998) Nat. BiotechnoL 16 :27-31.)

FuU length cDNAs, Expressed Sequence Tags (ESTs), or fragments or oUgomers thereof may comprise the elements of the microarray. Fragments or oUgomers suitable for hybridization can be selected using software weU known in the art such as LASERGENE software (DNASTAR). The array elements are hybridized with polynucleotides in a biological sample. The polynucleotides in the biological sample are conjugated to a fluorescent label or other molecular tag for ease of detection. After hybridization, nonhybridized nucleotides from the biological sample are removed, and a fluorescence scanner is used to detect hybridization at each array element. Alternatively, laser desorbtion and mass spectrometry may be used for detection of hybridization. The degree of complementarity and the relative abundance of each polynucleotide which hybridizes to an element on the microarray may be assessed. En one embodiment, microarray preparation and usage is described in detail below. Tissue or Cell Sample Preparation

Total RNA is isolated from tissue samples using the guanidinium thiocyanate method and poly(A)⁺ RNA is purified using the oUgo-(dT) ceUulose method. Each poly(A)⁺ RNA sample is reverse transcribed using MMLV reverse-ttanscriptase, 0.05 pg/μl oUgo-(dT) primer (21mer), IX first strand buffer, 0.03 units/μl RNase inhibitor, 500 μM dATP, 500 μM dGTP, 500 μM dTTP, 40 μM dCTP, 40 μM dCTP-Cy3 (BDS) or dCTP-Cy5 (Amersham Pharmacia Biotech). The reverse franscription reaction is performed in a 25 ml volume containing 200 ng poly(A)⁺ RNA with GEMBRIGHT kits (Incyte). Specific confrol poly(A)⁺ RNAs are synthesized by in vitro transcription from non-coding yeast genomic DNA. After incubation at 37° C for 2 br, each reaction sample (one with Cy3 and another with Cy5 labeUng) is treated with 2.5 ml of 0.5M sodium hydroxide and incubated for 20 minutes at 85° C to the stop the reaction and degrade the RNA. Samples are purified using two successive CHROMA SPIN 30 gel filtration spin columns (CLONTECH Laboratories, Inc. (CLONTECH), Palo Alto CA) and after combining, both reaction samples are ethanol precipitated using 1 ml of glycogen (1 mg/ml), 60 ml sodium acetate, and 300 ml of 100% ethanol. The sample is then dried to completion using a SpeedVAC (Savant Instruments Inc., HolbrookNY) and resuspended in 14 μl 5X SSC/0.2% SDS. Microarray Preparation

Sequences of the present invention are used to generate array elements. Each array element is ampUfied from bacterial ceUs containing vectors with cloned cDNA inserts. PCR ampUfication uses primers complementary to the vector sequences flanking the cDNA insert. Array elements are ampUfied in thirty cycles of PCR from an initial quantity of 1 -2 ng to a final quantity greater than 5 μg. AmpUfied array elements are then purified using SEPHACRYL-400 (Amersham Pharmacia Biotech). Purified array elements are immobiUzed on polymer-coated glass sUdes. Glass microscope sUdes (Corning) are cleaned by ultrasound in 0.1 % SDS and acetone, with extensive distiUed water washes between and after treatments. Glass sUdes are etched in 4% hydrofluoric acid (VWR Scientific Products Coφoration (VWR), West Chester PA), washed extensively in distilled water, and coated with 0.05% aminopropyl silane (Sigma) in 95% ethanol. Coated sUdes are cured in a 110°C oven. Array elements are appUed to the coated glass substrate using a procedure described in US

Patent No. 5,807,522, incoφorated herein by reference. 1 μl of the array element DNA, at an average concentration of 100 ng/μl, is loaded into the open capiUary printing element by a high-speed robotic apparatus. The apparatus then deposits about 5 nl of array element sample per sUde.

Microarrays are UV-crossUnked using a STRATALINKER UV-crossUnker (Stratagene). Microarrays are washed at room temperature once in 0.2% SDS and three times in distiUed water. Non-specific binding sites are blocked by incubation of microarrays in 0.2% casein in phosphate buffered saUne (PBS) (Tropix, Inc., Bedford MA) for 30 minutes at 60° C foUowed by washes in 0.2% SDS and distiUed water as before. Hybridization Hybridization reactions contain 9 μl of sample mixture consisting of 0.2 μg each of Cy3 and

Cy5 labeled cDNA synthesis products in 5X SSC, 0.2% SDS hybridization buffer. The sample mixture is heated to 65° C for 5 minutes and is aUquoted onto the microarray surface and covered with an 1.8 cm² coversUp. The arrays are transferred to a wateφroof chamber having a cavity just sUghtly larger than a microscope sUde. The chamber is kept at 100% humidity internaUy by the addition of 140 μl of 5X SSC in a corner of the chamber. The chamber containing the arrays is incubated for about 6.5 hours at 60° C. The arrays are washed for 10 min at 45°C in a first wash buffer (IX SSC, 0.1% SDS), three times for 10 minutes each at 45° C in a second wash buffer (0.1X SSC), and dried. Detection Reporter-labeled hybridization complexes are detected with a microscope equipped with an Innova 70 mixed gas 10 W laser (Coherent, Inc., Santa Clara CA) capable of generating spectral Unes at 488 nm for excitation of Cy3 and at 632 nm for excitation of Cy5. The excitation laser Ught is focused on the array using a 20X microscope objective (Nikon, Inc., MelviUe NY). The sUde containing the array is placed on a computer-confroUed X-Y stage on the microscope and raster- scanned past the objective. The 1.8 cm x 1.8 cm array used in the present example is scanned with a resolution of 20 micrometers.

In two separate scans, a mixed gas multiUne laser excites the two fluorophores sequentiaUy. Emitted Ught is spUt, based on wavelength, into two photomultipUer tube detectors (PMT R1477, Hamamatsu Photonics Systems, Bridgewater NJ) corresponding to the two fluorophores. Appropriate filters positioned between the array and the photomultipUer tubes are used to filter the signals. The emission maxima of the fluorophores used are 565 nm for Cy3 and 650 nm for Cy5. Each array is typicaUy scanned twice, one scan per fluorophore using the appropriate filters at the laser source, although the apparatus is capable of recording the spectra from both fluorophores simultaneously. The sensitivity of the scans is typicaUy caUbrated using the signal intensity generated by a cDNA control species added to the sample mixture at a known concentration. A specific location on the array contains a complementary DNA sequence, aUowing the intensity of the signal at that location to be correlated with a weight ratio of hybridizing species of 1 : 100,000. When two samples from different sources (e.g., representing test and control ceUs), each labeled with a different fluorophore, are hybridized to a single array for the puφose of identifying genes that are differentiaUy expressed, the calibration is done by labeUng samples of the caUbrating cDNA with the two fluorophores and adding identical amounts of each to the hybridization mixture.

The output of the photomultipUer tube is digitized using a 12-bit RTI-835H analog-to-digital (A/D) conversion board (Analog Devices, Inc., Norwood MA) instaUed in an IBM-compatible PC computer. The digitized data are displayed as an image where the signal intensity is mapped using a Unear 20-color transformation to a pseudocolor scale ranging from blue (low signal) to red (high signal). The data is also analyzed quantitatively. Where two different fluorophores are excited and measured simultaneously, the data are first corrected for optical crosstalk (due to overlapping emission spectra) between the fluorophores using each fluorophore's emission spectrum. A grid is superimposed over the fluorescence signal image such that the signal from each spot is centered in each element of the grid. The fluorescence signal within each element is then integrated to obtain a numerical value corresponding to the average intensity of the signal. The software used for signal analysis is the GEMTOOLS gene expression analysis program (Incyte). XI. Complementary Polynucleotides

Sequences complementary to the GTPB-encoding sequences, or any parts thereof, are used to detect, decrease, or inhibit expression of naturaUy occurring GTPB. Although use of oUgonucleotides comprising from about 15 to 30 base pairs is described, essentiaUy the same procedure is used with smaUer or with larger sequence fragments. Appropriate oUgonucleotides are designed using OLIGO 4.06 software (National Biosciences) and the coding sequence of GTPB. To inhibit transcription, a complementary oUgonucleotide is designed from the most unique 5' sequence and used to prevent promoter binding to the coding sequence. To inhibit translation, a complementary oUgonucleotide is designed to prevent ribosomal binding to the GTPB-encoding transcript. XII. Expression of GTPB

Expression and purification of GTPB is achieved using bacterial or virus-based expression systems. For expression of GTPB in bacteria, cDNA is subcloned into an appropriate vector containing an antibiotic resistance gene and an inducible promoter that directs high levels of cDNA transcription. Examples of such promoters include, but are not Umited to, the trp-lac (tac) hybrid promoter and the T5 or T7 bacteriophage promoter in conjunction with the lac operator regulatory element. Recombinant vectors are transformed into suitable bacterial hosts, e.g., BL21 (DE3). Antibiotic resistant bacteria express GTPB upon induction with isopropyl beta-D-thiogalactopyranoside (EPTG). Expression of GTPB in eukaryotic ceUs is achieved by infecting insect or mammaUan ceU Unes with recombinant Autographica caUfornica nuclear polyhedrosis virus (AcMNPV), commonly known as baculoviras. The nonessential polyhedrin gene of baculovirus is replaced with cDNA encoding GTPB by either homologous recombination or bacterial-mediated transposition involving transfer plasmid intermediates. Viral infectivity is maintained and the strong polyhedrin promoter drives high levels of cDNA transcription. Recombinant baculovirus is used to infect Spodoptera frugiperda (Sf9) insect ceUs in most cases, or human hepatocytes, in some cases. Infection of the latter requires additional genetic modifications to baculovirus. (See Engelhard, E.K. et al. (1994) Proc. Natl. Acad. Sci. USA 91:3224-3227; Sandig, V. et al. (1996) Hum. Gene Ther. 7:1937-1945.)

En most expression systems, GTPB is synthesized as a fusion protein with, e.g., glutathione S- transferase (GST) or a peptide epitope tag, such as FLAG or 6-His, permitting rapid, single-step, affinity-based purification of recombinant fusion protein from crude ceU lysates. GST, a 26-kilodalton enzyme from Schistosoma iaponicum, enables the purification of fusion proteins on immobiUzed glutathione under conditions that maintain protein activity and antigenicity (Amersham Pharmacia Biotech). FoUowing purification, the GST moiety can be proteolyticaUy cleaved from GTPB at specificaUy engineered sites. FLAG, an 8-amino acid peptide, enables immunoaffinity purification using commerciaUy available monoclonal and polyclonal anti-FLAG antibodies (Eastman Kodak). 6- His, a stretch of six consecutive histidine residues, enables purification on metal-chelate resins (QIAGEN). Methods for protein expression and purification are discussed in Ausubel (1995, supra, ch. 10 and 16) . Purified GTPB obtained by these methods can be used directly in the assays shown in Examples XVI and XVII, where appUcable. XIII. Functional Assays

GTPB function is assessed by expressing the sequences encoding GTPB at physiologicaUy elevated levels in mammaUan ceU culture systems. cDNA is subcloned into a mammaUan expression vector containing a strong promoter that drives high levels of cDNA expression. Vectors of choice include PCMV SPORT (Ufe Technologies) and PCR3.1 (Invitrogen, Carlsbad CA), both of which contain the cytomegalo virus promoter. 5-10 μg of recombinant vector are transiently transfected into a human ceU Une, for example, an endotheUal or hematopoietic ceU Une, using either Uposome formulations or elecfroporation. 1-2 μg of an additional plasmid containing sequences encoding a marker protein are co-transfected. Expression of a marker protein provides a means to distinguish transfected ceUs from nontransfected ceUs and is a reUable predictor of cDNA expression from the recombinant vector. Marker proteins of choice include, e.g., Green Fluorescent Protein (GFP; Clontech), CD64, or a CD64-GFP fusion protein. Flow cytometry (FCM), an automated, laser optics- based technique, is used to identify transfected ceUs expressing GFP or CD64-GFP and to evaluate the apoptotic state of the ceUs and other ceUular properties. FCM detects and quantifies the uptake of fluorescent molecules that diagnose events preceding or coincident with ceU death. These events include changes in nuclear DNA content as measured by staining of DNA with propidium iodide; changes in ceU size and granularity as measured by forward Ught scatter and 90 degree side Ught scatter; down-regulation of DNA synthesis as measured by decrease in bromodeoxyuridine uptake; alterations in expression of ceU surface and infraceUular proteins as measured by reactivity with specific antibodies; and alterations in plasma membrane composition as measured by the binding of fluorescein-conjugated Annexin V protein to the ceU surface. Methods in flow cytometry are discussed in Ormerod, M.G. (1994) Flow Cytometry, Oxford, New York NY.

The influence of GTPB on gene expression can be assessed using highly purified populations of ceUs transfected with sequences encoding GTPB and either CD64 or CD64-GFP. CD64 and CD64-GFP are expressed on the surface of transfected ceUs and bind to conserved regions of human immunoglobuUn G (IgG). Transfected ceUs are efficiently separated from nontransfected ceUs using magnetic beads coated with either human IgG or antibody against CD64 (DYNAL, Lake Success NY). mRNA can be purified from the ceUs using methods weU known by those of skiU in the art. Expression of mRNA encoding GTPB and other genes of interest can be analyzed by northern analysis or microarray techniques.

XIV. Production of GTPB Specific Antibodies

GTPB substantiaUy purified using polyacrylamide gel electrophoresis (PAGE; see, e.g., Harrington, M.G. (1990) Methods Enzymol. 182:488-495), or other purification techniques, is used to immunize rabbits and to produce antibodies using standard protocols.

Alternatively, the GTPB amino acid sequence is analyzed using LASERGENE software (DNASTAR) to determine regions of high immunogenicity, and a corresponding oUgopeptide is synthesized and used to raise antibodies by means known to those of skiU in the art. Methods for selection of appropriate epitopes, such as those near the C-terminus or in hydrophiUc regions are weU described in the art. (See, e.g., Ausubel, 1995, supra, ch. 11.)

TypicaUy, oUgopeptides of about 15 residues in length are synthesized using an ABI 431 A peptide synthesizer (AppUed Biosystems) using FMOC chemistry and coupled to KLH (Sigma- Aldrich, St. Louis MO) by reaction with N-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS) to increase immunogenicity. (See, e.g., Ausubel, 1995, supra.) Rabbits are immunized with the oUgopeptide-KLH complex in complete Freund's adjuvant. Resulting antisera are tested for antipeptide and anti-GTPB activity by, for example, binding the peptide or GTPB to a substrate, blocking with 1% BSA, reacting with rabbit antisera, washing, and reacting with radio-iodinated goat anti-rabbit IgG. XV. Purification of Naturally Occurring GTPB Using Specific Antibodies

Naturally occurring or recombinant GTPB is substantiaUy purified by immunoaffinity chromatography using antibodies specific for GTPB. An immunoaffinity column is constructed by covalently coupUng anti-GTPB antibody to an activated chromatographic resin, such as CNBr-activated SEPHAROSE (Amersham Pharmacia Biotech). After the coupUng, the resin is blocked and washed according to the manufacturer's instructions.

Media containing GTPB are passed over the immunoaffinity column, and the column is washed under conditions that aUow the preferential absorbance of GTPB (e.g., high ionic strength buffers in the presence of detergent). The column is eluted under conditions that disrupt antibody/GTPB binding (e.g., a buffer of pH 2 to pH 3, or a high concenfration of a chaofrope, such as urea or thiocyanate ion), and GTPB is coUected.

XVI. Identification of Molecules Which Interact with GTPB

GTPB, or biologicaUy active fragments thereof, are labeled with ¹²⁵I Bolton-Hunter reagent. (See, e.g., BoltonA.E. and W.M. Hunter (1973) Biochem. J. 133:529-539.) Candidate molecules previously arrayed in the weUs of a multi-weU plate are incubated with the labeled GTPB, washed, and any weUs with labeled GTPB complex are assayed. Data obtained using different concentrations of GTPB are used to calculate values for the number, affinity, and association of GTPB with the candidate molecules. Alternatively, molecules interacting with GTPB are analyzed using the yeast two-hybrid system as described in Fields, S. and O. Song (1989) Nature 340:245-246, or using commerciaUy available kits based on the two-hybrid system, such as the MATCHMAKER system (Clontech).

GTPB may also be used in the PATHCALLE G process (CuraGen Coip., New Haven CT) which employs the yeast two-hybrid system in a high-throughput manner to determine aU interactions between the proteins encoded by two large Ubraries of genes (Nandabalan, K. et al. (2000) U.S. Patent No. 6,057,101). XVII. Demonstration of GTPB Activity

The role of GTPB can be assayed in vitro by monitoring the mobiUzation of Ca^"1-1" as part of the signal transduction pathway. (See, e.g., Grynkievicz, G. et al. (1985) J. Biol. Chem. 260:3440; McCoU, S. et al. (1993) J. Immunol. 150:4550-4555; and Aussel, C et al. (1988) J. Immunol. 140:215-220.) The assay requires preloading neutrophils or T cells with a fluorescent dye such as FURA-2. Upon binding Ca⁺⁺, FURA-2 exhibits an absoφtion shift that can be observed by scanning the excitation spectrum between 300 and 400 nm, while monitoring the emission at 510 nm. When the cells are exposed to one or more activating stimuU artificiaUy (i.e., anti-CD3 antibody Ugation of the T cell receptor) or physiologicaUy (i.e., by aUogeneic stimulation), Ca⁺⁺ flux takes place. Ca⁺⁺ flux results from the release of Ca⁺⁺ from infraceUular organeUes or from Ca⁺⁺ entry into the ceU through activated Ca⁺⁺ channels. This flux can be observed and quantified by assaying the ceUs in a fluorometer or fluorescence activated ceU sorter. Measurements of Ca⁺⁺ flux are compared between ceUs in their normal state and those preloaded with GTPB. Increased mobiUzation attributable to increased GTPB availabiUty results in increased emission.

Alternatively, GTPB activity is measured by quantifying the amount of a non-hydrolyzable GTP analogue, GTPγS, bound over a 10 minute incubation period. Varying amounts of GTPB are incubated at 30°C in 50mM Tris buffer, pH 7.5, containing ImM dithiothreitol, ImM EDTA and lμM [³⁵S]GTPγS. Samples are passed through nitroceUulose filters and washed twice with a buffer consisting of 50mM Tris-HCl, pH 7.8, ImM NaN₃, lOmM MgCl₂, ImM EDTA, 0.5mM dithiothreitol, O.OlmM PMSF, and 200mM NaCl. The filter-bound counts are measured by Uquid scintiUation to quantify the amount of bound [³⁵S]GTPγS. GTPB activity may also be measured as the amount of GTP hydrolysed over a 10 minute incubation period at 37°C GTPB is incubated in 50mM Tris-HCl buffer, pH 7.8, containing ImM dithiothreitol, 2mM EDTA, lOμM [a-³²P]GTP, and lμM H-rab protein. GTPase activity is initiated by adding MgCl₂ to a final concentration of 10 mM. Samples are removed at various time points, mixed with an equal volume of ice-cold 0.5mM EDTA, and frozen. AUquots are spotted onto polyethyleneimine-ceUulose thin layer chromatography plates, which are developed in IM LiCl, dried, and autoradiographed. The signal detected is proportional to GTPB activity.

Alternatively, GTPB activity may be demonstrated as the abiUty to interact with its associated Gα or LMW GTPase in an in vitro binding assay. The candidate Gα or LMW GTPases are expressed as fusion proteins with glutathione S-fransferase (GST), and purified by affinity chromatography on glutathione-Sepharose. The Gα or LMW GTPases are loaded with GDP by incubating 20 mM Tris buffer, pH 8.0, containing 100 mM NaCl, 2 mM EDTA, 5 mM MgC12, 0.2 mM DTT, 100 μM AMP-PNP and 10 μM GDP at 30°C for 20 minutes. GTPB is expressed as a FLAG fusion protein in a baculovirus system. Extracts of these baculovirus cells containing GTPB-FLAG fusion proteins are precleared with GST beads, then incubated with GST-GTPase fusion proteins. The complexes formed are precipitated by glutathione-Sepharose and separated by SDS- polyacrylamide gel electrophoresis. The separated proteins are blotted onto nitroceUulose membranes and probed with commerciaUy available anti-FLAG antibodies. GTPB activity is proportional to the amount of GTPB-FLAG fusion protein detected in the complex.

Another alternative assay to detect GTPB activity is the use of a yeast two-hybrid system (Zalcman, G. et al. (1996) J. Biol. Chem. 271 :30366-30374). SpecificaUy, a plasmid such as pGADl 318 which may contain the coding region of GTPB can be used to transform reporter L40 yeast ceUs which contain the reporter genes LacZ and HIS3 downstream from the binding sequences for LexA. These yeast ceUs have been previously transformed with a pLexA-Rab6-GDP (mouse) plasmid or with a plasmid which contains pLexA-la in C. The pLEXA-lamin C ceUs serve as a negative control. The fransformed ceUs are plated on a histidine-free medium and incubated at 30 °C for 3 days. His⁺ colonies are subsequently patched on selective plates and assayed for β- galactosidase activity by a filter assay. GTPB binding with Rab6-GDP is indicated by positive His⁺/lacZ⁺ activity for the ceUs transformed with the plasmid containing the mouse Rab6-GDP and negative His⁺/lacZ⁺ activity for those fransformed with the plasmid containing lamin C

Various modifications and variations of the described methods and systems of the invention wiU be apparent to those skiUed in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with certain embodiments, it should be understood that the invention as claimed should not be unduly Umited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention wliich are obvious to those skiUed in molecular biology or related fields are intended to be within the scope of the foUowing claims.

Table 1

Table 2

Table 3

∞ t

Table 3 cont.

Table 4

Table 4 (cont.)

Table 5

oo

ON

Table 6

Table 7

Program Description Reference Parameter Threshold

ABI FACTURA A program that removes vector sequences and Applied Biosystems, Foster City, CA. masks ambiguous bases in nucleic acid sequences.

ABI PARACELFDF A Fast Data Finder useful in comparing and Applied Biosystems, Foster City, CA; Mismatch <50% annotating amino acid or nucleic acid sequences. Paracel Inc., Pasadena, CA. ABI AutoAssembler A program that assembles nucleic acid sequences. Applied Biosystems, Foster City, CA.

BLAST A Basic Local Alignment Search Tool useful in Altschul, S.F. et al. (1990) J. Mol. Biol. ESTs: ProbabiUty value= 1.0E-8 sequence similarity search for amino acid and 215:403-410; Altschul, S.F. et al. (1997) or less nucleic acid sequences. BLAST includes five Nucleic Acids Res. 25:3389-3402. Full Length sequences: Probabili functions: blastp, blastn, blastx, tblastn, and tblastx. value= l.OE-10 or less

FASTA A Pearson and Lipman algorithm that searches for Pearson, W.R. and D.J. Lipman (1988) Proc. ESTs: fasta E value=1.06E-6 similarity between a query sequence and a group of Natl. Acad Sci. USA 85:2444-2448; Pearson, Assembled ESTs: fasta Identity= sequences of the same type. FASTA comprises as W.R. (1990) Methods Enzymol. 183:63-98; 95% or greater and least five functions: fasta, tfasta, fastx, tfastx, and and Smith, T.F. and M.S. Waterman (1981) Match length=200 bases or great ssearch. Adv. Appl. Math. 2:482-489. fastx E value=1.0E-8 or less

Full Length sequences: fastx score=100 or greater

BLIMPS A BLocks IMProved Searcher that matches a Henikoff, S. and J.G. Henikoff (1991) Nucleic ProbabiUty value= 1.0E-3 or less sequence against those in BLOCKS, PRINTS, Acids Res. 19:6565-6572; Henikoff, J.G. and DOMO, PRODOM, and PFAM databases to search S. Henikoff (1996) Methods Enzymol. for gene families, sequence homology, and structural 266:88-105; and Attwood, T.K. et al. (1997) J. fingerprint regions. Chem. Inf. Comput. Sci. 37:417-424.

HMMER An algorithm for searching a query sequence against Krogh, A. et al. (1994) J. Mol. Biol. PFAM hits: ProbabiUty value= hidden Markov model (HMM)-based databases of 235:1501-1531; Sonnhammer, E.L.L. et al. 1.0E-3 or less protein family consensus sequences, such as PFAM. (1988) Nucleic Acids Res. 26:320-322; Signal peptide hits: Score= 0 or Durbin, R. et al. (1998) Our World View, in a greater Nutshell, Cambridge Univ. Press, pp. 1-350.

Table 7 (cont.)

Program Description Reference Parameter Threshold

ProfileScan An algorithm that searches for structural and sequence Gribskov, M. et al. (1988) CABIOS 4:61-66; Normalized quality score≥GC motifs in protein sequences that match sequence patterns Gribskov, M. et al. (1989) Methods Enzymol. specified "HIGH" value for th defined in Prosite. 183:146-159; Bairoch, A. et al. (1997) particular Prosite motif. Nucleic Acids Res. 25:217-221. Generally, score=l .4-2.1.

Phred A base-caUing algorithm that examines automated Ewing, B. et al. (1998) Genome Res. sequencer traces with high sensitivity and probability. 8:175-185; Ewing, B. and P. Green (1998) Genome Res. 8:186-194.

Phrap A Phils Revised Assembly Program including SWAT and Smith, T.F. and M.S. Waterman (1981) Adv. Score= 120 or greater; CrossMatch, programs based on efficient implementation Appl. Math. 2:482-489; Smith, T.F. and M.S. Match length= 56 or greater of the Smith-Waterman algorithm, useful in searching Waterman (1981) J. Mol. Biol. 147:195-197; sequence homology and assembUng DNA sequences. and Green, P., University of Washington, Seattle, WA.

Consed A graphical tool for viewing and editing Phrap assemblies. Gordon, D. et al. (1998) Genome Res. 8:195-202. SPScan A weight matrix analysis program that scans protein Nielson, H. et al. (1997) Protein Engineering Score=3.5 or greater sequences for the presence of secretory signal peptides. 10:1-6; Claverie, J.M. and S. Audic (1997) CABIOS 12:431-439.

TMAP A program that uses weight matrices to delineate Persson, B. and P. Argos (1994) J. Mol. Biol. transmembrane segments on protein sequences and 237:182-192; Persson, B. and P. Argos (1996) determine orientation. Protein Sci. 5:363-371.

TMHMMER A program that uses a hidden Markov model (HMM) to Sonnhammer, E.L. et al. (1998) Proc. Sixth Intl. deUneate transmembrane segments on protein sequences Conf. on InteHigent Systems for Mol. Biol., and determine orientation. Glasgow et al., eds., The Am. Assoc. for Artificial Intelligence Press, Menlo Park, CA, pp. 175-182.

Motifs A program that searches amino acid sequences for patterns Bairoch, A. et al. (1997) Nucleic Acids Res. 25:217-221; that matched those defined in Prosite.

Wisconsin Package Program Manual, version 9, page M51-59, Genetics Computer Group, Madison, WI.

Claims

What is claimed is:

1. An isolated polypeptide selected from the group consisting of: a) a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, b) a polypeptide comprising a naturaUy occurring amino acid sequence at least 90% identical to an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7, c) a biologicaUy active fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-7, and d) an immunogenic fragment of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7.

2. An isolated polypeptide of claim 1 selected from the group consisting of SEQ ID NO: 1-7.

3. An isolated polynucleotide encoding a polypeptide of claim 1.

4. An isolated polynucleotide encoding a polypeptide of claim 2.

5. An isolated polynucleotide of claim 4 selected from the group consisting of SEQ ED NO:8- 14.

6. A recombinant polynucleotide comprising a promoter sequence operably Unked to a polynucleotide of claim 3.

7. A ceU transformed with a recombinant polynucleotide of claim 6.

8. A transgenic organism comprising a recombinant polynucleotide of claim 6.

9. A method for producing a polypeptide of claim 1 , the method comprising: a) culturing a ceU under conditions suitable for expression of the polypeptide, wherein said ceU is transformed with a recombinant polynucleotide, and said recombinant polynucleotide comprises a promoter sequence operably Unked to a polynucleotide encoding the polypeptide of claim 1, and b) recovering the polypeptide so expressed.

10. An isolated antibody which specificaUy binds to a polypeptide of claim 1.

11. An isolated polynucleotide selected from the group consisting of: a) a polynucleotide comprising a polynucleotide sequence selected from the group consisting of SEQ ID NO:8-14, b) a polynucleotide comprising a naturaUy occurring polynucleotide sequence at least 90% identical to a polynucleotide sequence selected from the group consisting of SEQ ID NO:8-14, c) a polynucleotide complementary to a polynucleotide of a), d) a polynucleotide complementary to a polynucleotide of b), and e) an RNA equivalent of a)-d).

12. An isolated polynucleotide comprising at least 60 contiguous nucleotides of a polynucleotide of claim 11.

13. A method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide of claim 11, the method comprising: a) hybridizing the sample with a probe comprising at least 20 contiguous nucleotides comprising a sequence complementary to said target polynucleotide in the sample, and which probe specificaUy hybridizes to said target polynucleotide, under conditions whereby a hybridization complex is formed between said probe and said target polynucleotide or fragments thereof, and b) detecting the presence or absence of said hybridization complex, and, optionaUy, if present, the amount thereof.

14. A method of claim 13, wherein the probe comprises at least 60 contiguous nucleotides.

15. A method for detecting a target polynucleotide in a sample, said target polynucleotide having a sequence of a polynucleotide of claim 11, the method comprising: a) ampUfying said target polynucleotide or fragment thereof using polymerase chain reaction ampUfication, and b) detecting the presence or absence of said ampUfied target polynucleotide or fragment thereof, and, optionaUy, if present, the amount thereof.

16. A composition comprising a polypeptide of claim 1 and a pharmaceutically acceptable excipient.

17. A composition of claim 16, wherein the polypeptide has an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7.

18. A method for treating a disease or condition associated with decreased expression of functional GTPB, comprising administering to a patient in need of such freatment the composition of claim 16.

19. A method for screening a compound for effectiveness as an agonist of a polypeptide of claim 1, the method comprising: a) exposing a sample comprising a polypeptide of claim 1 to a compound, and b) detecting agonist activity in the sample.

20. A composition comprising an agonist compound identified by a method of claim 19 and a pharmaceuticaUy acceptable excipient.

21. A method for treating a disease or condition associated with decreased expression of functional GTPB, comprising administering to a patient in need of such freatment a composition of claim 20.

22. A method for screening a compound for effectiveness as an antagonist of a polypeptide of claim 1, the method comprising: a) exposing a sample comprising a polypeptide of claim 1 to a compound, and b) detecting antagonist activity in the sample.

23. A composition comprising an antagonist compound identified by a method of claim 22 and a pharmaceuticaUy acceptable excipient.

24. A method for treating a disease or condition associated with overexpression of functional

GTPB, comprising administering to a patient in need of such treatment a composition of claim 23.

25. A method of screening for a compound that specificaUy binds to the polypeptide of claim 1, said method comprising the steps of: a) combining the polypeptide of claim 1 with at least one test compound under suitable conditions, and b) detecting binding of the polypeptide of claim 1 to the test compound, thereby identifying a compound that specificaUy binds to the polypeptide of claim 1.

26. A method of screening for a compound that modulates the activity of the polypeptide of claim 1, said method comprising: a) combining the polypeptide of claim 1 with at least one test compound under conditions permissive for the activity of the polypeptide of claim 1 , b) assessing the activity of the polypeptide of claim 1 in the presence of the test compound, and c) comparing the activity of the polypeptide of claim 1 in the presence of the test compound with the activity of the polypeptide of claim 1 in the absence of the test compound, wherein a change in the activity of the polypeptide of claim 1 in the presence of the test compound is indicative of a compound that modulates the activity of the polypeptide of claim 1.

27. A method for screening a compound for effectiveness in altering expression of a target polynucleotide, wherein said target polynucleotide comprises a sequence of claim 5, the method comprising: a) exposing a sample comprising the target polynucleotide to a compound, under conditions suitable for the expression of the target polynucleotide, b) detecting altered expression of the target polynucleotide, and c) comparing the expression of the target polynucleotide in the presence of varying amounts of the compound and in the absence of the compound.

28. A method for assessing toxicity of a test compound, said method comprising: a) treating a biological sample containing nucleic acids with the test compound; b) hybridizing the nucleic acids of the treated biological sample with a probe comprising at least 20 contiguous nucleotides of a polynucleotide of claim 11 under conditions whereby a specific hybridization complex is formed between said probe and a target polynucleotide in the biological sample, said target polynucleotide comprising a polynucleotide sequence of a polynucleotide of claim 11 or fragment thereof; c) quantifying the amount of hybridization complex; and d) comparing the amount of hybridization complex in the treated biological sample with the amount of hybridization complex in an untreated biological sample, wherein a difference in the amount of hybridization complex in the treated biological sample is indicative of toxicity of the test compound.

29. A diagnostic test for a condition or disease associated with the expression of GTPB in a biological sample comprising the steps of: a) combining the biological sample with an antibody of claim 10, under conditions suitable for the antibody to bind the polypeptide and form an antibody:polypeptide complex; and b) detecting the complex, wherein the presence of the complex correlates with the presence of the polypeptide in the biological sample.

30. The antibody of claim 10, wherein the antibody is: a) a chimeric antibody, b) a single chain antibody, c) a Fab fragment, d) a F(ab')₂ fragment, or e) a humanized antibody.

31. A composition comprising an antibody of claim 10 and an acceptable excipient.

32. A method of diagnosing a condition or disease associated with the expression of GTPB in a subject, comprising administering to said subject an effective amount of the composition of claim 31.

33. A composition of claim 31, wherein the antibody is labeled.

34. A method of diagnosing a condition or disease associated with the expression of GTPB in a subject, comprising administering to said subject an effective amount of the composition of claim 33.

35. A method of preparing a polyclonal antibody with the specificity of the antibody of claim

10 comprising: a) immunizing an animal with a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO.1-7, or an immunogenic fragment thereof, under conditions to eUcit an antibody response; b) isolating antibodies from said animal; and c) screening the isolated antibodies with the polypeptide, thereby identifying a polyclonal antibody which binds specificaUy to a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO : 1 -7.

36. An antibody produced by a method of claim 35.

37. A composition comprising the antibody of claim 36 and a suitable carrier.

38. A method of making a monoclonal antibody with the specificity of the antibody of claim 10 comprising: a) immunizing an animal with a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO:l-7, or an immunogenic fragment thereof, under conditions to eUcit an antibody response; b) isolating antibody producing ceUs from the animal; c) fusing the antibody producing ceUs with immortaUzed ceUs to form monoclonal antibody- producing hybridoma ceUs; d) culturing the hybridoma ceUs; and e) isolating from the culture monoclonal antibody which binds specificaUy to a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7.

39. A monoclonal antibody produced by a method of claim 38.

40. A composition comprising the antibody of claim 39 and a suitable carrier.

41. The antibody of claim 10, wherein the antibody is produced by screening a Fab expression Ubrary.

42. The antibody of claim 10, wherein the antibody is produced by screening a recombinant immunoglobuUn Ubrary.

43. A method for detecting a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7 in a sample, comprising the steps of: a) incubating the antibody of claim 10 with a sample under conditions to aUow specific binding of the antibody and the polypeptide; and b) detecting specific binding, wherein specific binding indicates the presence of a polypeptide having an amino acid sequence selected from the group consisting of SEQ ED NO: 1-7 in the sample.

44. A method of purifying a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO:l-7 from a sample, the method comprising: a) incubating the antibody of claim 10 with a sample under conditions to aUow specific binding of the antibody and the polypeptide; and b) separating the antibody from the sample and obtaining the purified polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1-7.

45. A polypeptide of claim 1 , comprising the amino acid sequence of SEQ ID NO: 1.

46. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ED NO:2.

47. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:3.

48. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:4.

49. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ED NO:5.

50. A polypeptide of claim 1, comprising the amino acid sequence of SEQ ID NO:6.

51. A polypeptide of claim 1 , comprising the amino acid sequence of SEQ ID NO:7.

52. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ED NO:8.

53. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ED NO:9.

54. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ED NO:10.

55. A polynucleotide of claim 11 , comprising the polynucleotide sequence of SEQ ID NO:l 1.

56. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO: 12.

57. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ED NO:13.

58. A polynucleotide of claim 11, comprising the polynucleotide sequence of SEQ ID NO: 14.