HUMAN BRAINIAC-5

Abstract: The present invention relates to novel Brainiac-5 polypeptides which are members of the Brainiac family. In particular, isolated nucleic acid molecules are provided encoding the human Brainiac-5 polypeptides. Brainiac-5 polypeptides are also provided as are vectors, host cells and recombinant methods for producing the same. The invention further relates to screening methods for identifying agonists and antagonists of Brainiac-5 activities. Also provided are diagnostic methods for detecting immune and nervous system-related disorders and therapeutic methods for treating, preventing, and/or diagnosing immune and nervous system-related disorders.

Description: Human Brainiac-5 Field ofthe Invention The present invention relates to a novel human gene encoding a polypeptide related to the Notch family. More specifically, isolated nucleic acid molecules are provided encoding a human polypeptide named Brainiac-5. Brainiac-5 polypeptides are also provided, as are vectors, host cells and recombinant methods for producing the same. Also provided are diagnostic methods for detecting disorders related to the immune and nervous systems, and therapeutic methods for treating and/or preventing such disorders. The invention further relates to screening methods for identifying agonists and antagonists of Brainiac-5 activity. Background ofthe Invention Control of cell division is a basic aspect of multicellular existence that depends upon a programmed series of events. One factor in cellular proliferation and its control is the presence of various polypeptide growth factors. Growth factors are essential components of growth media for in vitro cell culture and are involved in cell survival in vivo. A partial list of growth factors identified to date include platelet-derived growth factor (PDGF; implicated in the repair of the vascular system in vivo); epidermal growth factor (EGF; which acts as a mitogen for cells of ectodermal and mesodermal origin); transforming growth factor (TGF)-alpha (which acts as a mitogen similarly to EGF, with the exception that it enables normal cells to grow in soft-agar); transforming growth factor (TGF)-beta (a mitogen for some cells and a growth inhibitor for others); and nerve growth factor (NGF; which is involved in the development and maintenance of sympathetic and embryonic neurons). (Watson, et al., Molecular Biology ofthe Gene, p. 975; Benjamin/Cummings (1987).) It is clear that particular cell types require particular growth factors for normal growth and maintenance. Peptide growth factors are produced and secreted from a variety of tissues. The target cells are typically located near the site of release of the growth factor (paracrine response). In addition to growth promoting and differentiation-inducing activities, growth factors elicit a wide variety of effects on their target cells and are involved in processes such as inflammation, immune reactions, and wound repair. (See, Pimentel, E. Handbook of Growth Factors, Volume 1: General Basics (CRC Press 1994).) The Notch family of transmembrane receptor proteins have been demonstrated to mediate cell fate decisions, and mutations in mammalian Notch genes have been implicated in leukemia, cervical cancer, colon cancer, breast cancer, stroke, and dementia. In Drosophila, three genes, fringe, Serrate, and Delta, are involved in the cellular interactions leading to Notch activation. Delta and Serrate encode transmembrane ligands for Notch, whereas fringe encodes a pioneer protein. Human homologs of Notch, Delta, Serrate (termed "Jagged"), and Fringe (termed "Radical Fringe" and "Lunatic Fringe") have been cloned. Expression studies in mouse embryos support a conserved role for mammalian Fringe family members in participation in the Notch signaling pathway. Myocardial hypertrophy refers to a focal or general enlargement of the heart. Normal hypertrophy is a compensatory action which functions to maintain the pumping action of the heart. Abnormal hypertrophy occurs in a number of situations including hypertension, myocardial infarction, valve disease, and cardiomyopathy. (Simpson, P.C. Heart Failure 5: 113 (1989).) The effects of peptide growth factors on cardiac myocytes are reflected in differentiated patterns of gene expression. For example, stimulation of the alpha-adrenergic receptor induces hypertrophy of cultured cardiac myocytes and produces specific changes in gene expression at the level of transcription. (Simpson, P. C. "Cardiac Myocyte Hypertrophy," Molecular Biology of the Cardiovascular System, Roberts, R. et al, ed.: 125-133 (1990).) In cardiac myocytes, the growth factors TGF-beta 1 and basic FGF concomitantly elicit complex and heterogeneous responses: selective inhibition of certain adult transcripts, concurrent with the upregulation of "fetal" contractile protein genes. (Schneider, et al., "Oncogenes and Myogenesis," Molecular Biology ofthe Cardiovascular System, Roberts, R. et al, ed.: 63-71 (1990).) Monitoring of growth factor gene expression in myocytes and other cells of the heart, including connective tissue, would be useful in detecting and studying abnormal hypertrophy both in vitro and in vivo. Organ and clonal cell systems have been developed to analyze cardiomyogenic differentiation. (See, for example, Bader, D. et al., Molecular Biology ofthe Cardiovascular System, Roberts, R. et al., ed.: 41-49 (1990).) Differentiation in these systems can be monitored by in vitro analysis of cardiac myogenesis and monoclonal antibodies that have been raised against muscle-specific protein. Additionally, polypeptide growth factors are very important cell culture reagents for stimulating cellular growth and aiding survival of the cells in vitro. Homology with other members of the Fringe family and indication that mammalian Fringe family members play an evolutionarily conserved role in the Notch signaling pathway suggests that these polypeptides, as well as Brainiac-5 polypeptides, have uses which include the treatment or prevention of disorders of cell fate or differentiation (e.g., cancerous conditions, such as, leukemia, cervical cancer, colon cancer, breast cancer), treatment or prevention of disorders of the nervous system, and stimulation of tissue repair and regeneration. The search continues to exist for polypeptides that stimulate and/or inhibit growth of particular cells for both in vitro and in vivo uses. In addition, the search continues for novel tissue specific markers that can be employed qualitatively to help identify a particular cell or tissue type and employed qualitatively to assess whether cells, tissues or organs are abnormal in their expression of a particular polypeptide. Summary ofthe Invention The present invention provides isolated nucleic acid molecules comprising a polynucleotide encoding at least a portion of the Brainiac-5 polypeptide having the complete amino acid sequence shown in SEQ ID NO:2 or the complete amino acid sequence encoded by the cDNA clone deposited as plasmid DNA as ATCC Deposit Number 203572 on January 11, 1999. The nucleotide sequence determined by sequencing the deposited Brainiac-5 clone, which is shown in Figures 1A and IB (SEQ ID NO:l), contains an open reading frame encoding an apparently incomplete polypeptide of 278 amino acid residues, beginning with an initial valine codon at nucleotide positions 1-3, and a predicted molecular weight of about 30,475 Daltons. Nucleic acid molecules of the invention include those encoding the complete amino acid sequence shown in SEQ ID NO:2 excepting an N-terminal methionine residue, or the complete amino acid sequence encoded by the cDNA clone in ATCC Deposit Number 203572 excepting an N-terminal methionine, which molecules also can encode additional amino acids fused to the N-terminus and/or C-terminus of the Brainiac-5 amino acid sequence. Thus, one embodiment of the invention provides an isolated nucleic acid molecule comprising, or alternatively consisting of, a polynucleotide having a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the Brainiac-5 polypeptide having the complete amino acid sequence in SEQ ID NO:2 (i.e., positions 1 to 278 of SEQ ID NO:2); (b) a nucleotide sequence encoding the Brainiac-5 polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; (c) a nucleotide sequence encoding the mature Brainiac-5 polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; and (d) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b) or (c), above. Further embodiments of the invention include isolated nucleic acid molecules that comprise a polynucleotide having (i.e., comprising, or alternatively consisting of) a nucleotide sequence at least 90% identical, and more preferably at least 92%, 95%, 96%, 97%, 98% or 99% identical, to any of the nucleotide sequences in (a), (b), (c) or (d), above, or a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide in (a), (b), (c) or (d), above. This polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues. An additional nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising, or alternatively consisting of, a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a Brainiac-5 polypeptide having an amino acid sequence in (a), (b) or (c), above. A further nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising, or alternatively consisting of, a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide having an amino acid sequence which contains at least one conservative amino acid substitution, but not more than 50 conservative amino acid substitutions, even more preferably, not more than 40 conservative amino acid substitutions, still more preferably, not more than 30 conservative amino acid substitutions, and still even more preferably, not more than 20 conservative amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide to have an amino acid sequence which contains not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 conservative amino acid substitutions. The present invention also relates to recombinant vectors, which include the isolated nucleic acid molecules of the present invention, and to host cells containing the recombinant vectors, as well as to methods of making such vectors and host cells and for using them for production of Brainiac-5 polypeptides or peptides by recombinant techniques. In accordance with a further embodiment of the present invention, there is provided a process for producing such polypeptide by recombinant techniques comprising culturing recombinant prokaryotic and/or eukaryotic host cells, containing a human Brainiac-5 nucleic acid sequence, under conditions promoting expression of said polypeptide and subsequent recovery of said polypeptide. The invention also provides an isolated Brainiac-5 polypeptide comprising, or alternatively consisting of, an amino acid sequence selected from the group consisting of: (a) the amino acid sequence of the Brainiac-5 polypeptide having the complete amino acid sequence shown in SEQ ID NO:2 (i.e., positions 1-278 of SEQ ID NO:2); (b) the complete amino acid sequence encoded by the cDNA clone contained in the ATCC Deposit No. 203572; (c) the complete amino acid sequence of the predicted mature Brainiac-5 polypeptide encoded by the cDNA clone contained in the ATCC Deposit No. 203572. The polypeptides of the present invention also include polypeptides having (i.e., comprising, or alternatively consisting of) an amino acid sequence at least 80% identical, more preferably at least 90% identical, and still more preferably 92%, 95%, 96%, 97%, 98% or 99% identical to those described in (a), (b) or (c), above. An additional embodiment of the invention relates to a peptide or polypeptide which comprises, or alternatively consists of, the amino acid sequence of an epitope-bearing portion of a Brainiac-5 polypeptide having (i.e., comprising, or alternatively consisting of) an amino acid sequence described in (a), (b) or (c), above. Peptides or polypeptides having the amino acid sequence of an epitope-bearing portion of a Brainiac-5 polypeptide of the invention include portions of such polypeptides with at least six or seven, preferably at least nine, and more preferably at least about 30 amino acids to about 50 amino acids, although epitope-bearing polypeptides of any length up to and including the entire amino acid sequence of a polypeptide of the invention described above also are included in the invention. A further embodiment of the invention relates to a peptide or polypeptide which comprises, or alternatively consists of, the amino acid sequence of a Brainiac-5 polypeptide having an amino acid sequence which contains at least one conservative amino acid substitution, but not more than 50 conservative amino acid substitutions, even more preferably, not more than 40 conservative amino acid substitutions, still more preferably, not more than 30 conservative amino acid substitutions, and still even more preferably, not more than 20 conservative amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a peptide or polypeptide to have an amino acid sequence which comprises the amino acid sequence of a Brainiac-5 polypeptide, which contains at least one, but not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 conservative amino acid substitutions. In another embodiment, the invention provides an isolated antibody that binds specifically to a Brainiac-5 polypeptide having an amino acid sequence described in (a), (b) or (c), above. The invention further provides methods for isolating antibodies that bind specifically to a Brainiac-5 polypeptide having an amino acid sequence as described herein. Such antibodies are useful diagnostically or therapeutically as described below. The invention also provides for pharmaceutical compositions comprising Brainiac-5 polypeptides, particularly human Brainiac-5 polypeptides, which may be employed, for instance, to treat, prevent, and/or diagnose immune and/or nervous system diseases and disorders. Methods of treating individuals in need of Brainiac-5 polypeptides are also provided. The invention further provides compositions comprising a Brainiac-5 polynucleotide or polypeptide for administration to cells in vitro, to cells ex vivo and to cells in vivo, or to a multicellular organism. In certain particularly preferred embodiments of this aspect of the invention, the compositions comprise a Brainiac-5 polynucleotide for expression of a Brainiac-5 polypeptide in a host organism for treatment, prevention, and/or diagnosis of disease. Particularly preferred in this regard is expression in a human patient for treatment, prevention, and/or diagnosis of a dysfunction associated with aberrant endogenous activity of a Brainiac-5 polynucleotide and/or polypeptide. The present invention also provides a screening method for identifying compounds capable of enhancing or inhibiting a biological activity of the Brainiac-5 polypeptide, which involves contacting a receptor whose activity is inhibited or enhanced by the Brainiac-5 polypeptide with the candidate compound in the presence of a Brainiac-5 polypeptide, assaying cell division activity of the receptor in the presence of the candidate compound and of Brainiac-5 polypeptide, and comparing the receptor activity to a standard level of activity, the standard being assayed when contact is made between the receptor and in the presence of the Brainiac-5 polypeptide and the absence of the candidate compound In this assay, an increase in receptor activity over the standard indicates that the candidate compound is an agonist of Brainiac-5 activity and a decrease in receptor activity compared to the standard indicates that the compound is an antagonist of Brainiac-5 activity. In another embodiment, a screening assay for agonists and antagonists is provided which involves determining the effect a candidate compound has on Brainiac-5 binding to another member of the Notch family (e.g., fringe, Serrate, Delta, Jagged, Radical Fringe, Lunatic Fringe, and Maniac Fringe). In particular, the method involves contacting the Notch family member with a Brainiac-5 polypeptide and a candidate compound and determining whether Brainiac-5 polypeptide binding to the Notch family member is increased or decreased due to the presence of the candidate compound. In this assay, an increase in binding of Brainiac-5 over the standard binding indicates that the candidate compound is an agonist of Brainiac-5 binding activity and a decrease in Brainiac-5 binding compared to the standard indicates that the compound is an antagonist of Brainiac-5 binding activity. The antagonists may be employed to treat and/or prevent, diseases, disorders or conditions including, but not limited to, septic shock, inflammation, cerebral malaria, activation of the HIV virus, graft-host rejection, bone resorption, rheumatoid arthritis, cachexia (wasting or malnutrition), immune system function, lymphoma, and autoimmune disorders. In yet another embodiment, the Brainiac-5 polypeptide(s) may bind to a cell surface polypeptide which also function as a viral receptor or coreceptor. Thus, Brainiac-5, or agonists or antagonists thereof, may be used to regulate viral infectivity at the level of viral binding or interaction with the Brainiac-5 receptor or coreceptor or during the process of viral internalization or entry into the cell. It has been discovered that Brainiac-5 is expressed not only in ovarian tumor, but also (using BLAST analysis of the HGS EST database) in bone marrow stromal cells and synovial sarcoma. Therefore, nucleic acids of the invention are useful as hybridization probes for differential identification of the tissue(s) or cell type(s) present in a biological sample. Similarly, polypeptides and antibodies directed to those polypeptides are useful to provide immunological probes for differential identification of the tissue(s) or cell type(s). In addition, for a number of disorders of the above tissues or cells, particularly of the immune system, significantly higher or lower levels of Brainiac-5 gene expression may be detected in certain tissues (e.g., cancerous and wounded tissues) or bodily fluids (e.g., serum, plasma, urine, synovial fluid or spinal fluid) taken from an individual having such a disorder, relative to a "standard" Brainiac-5 gene expression level, i.e., the Brainiac-5 expression level in healthy tissue from an individual not having the immune system disorder. Thus, the invention provides a diagnostic method useful during diagnosis of such a disorder, which involves: (a) assaying Brainiac-5 gene expression level in cells or body fluid of an individual; (b) comparing the Brainiac-5 gene expression level with a standard Brainiac-5 gene expression level, whereby an increase or decrease in the assayed Brainiac-5 gene expression level compared to the standard expression level is indicative of disorder in the immune system. Another embodiment of the invention is related to a method for treating or diagnosing an individual in need of an increased level of Brainiac-5 activity in the body comprising administering to such an individual a composition comprising a therapeutically effective amount of an isolated Brainiac-5 polypeptide of the invention or an agonist thereof. A further embodiment of the invention is related to a method for treating or diagnosing an individual in need of a decreased level of Brainiac-5 activity in the body comprising, administering to such an individual a composition comprising a therapeutically effective amount of a Brainiac-5 antagonist. Preferred antagonists for use in the present invention are Brainiac-5-specific antibodies. Brief Description ofthe Figures The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims. Figures 1A and IB show the nucleotide sequence (SEQ ID NO: l) and deduced amino acid sequence (SEQ ID NO:2) of Brainiac-5. A single potential asparagine-linked glycosylation site is marked in the amino acid sequence of Brainiac-5. The potential site of glycosylation begins at asparagine-79 in Figures 1A and IB (SEQ ID NO:2). The potential glycosylation site is marked with a bold pound symbol (#) above the nucleotide sequence coupled with a bolded one letter abbreviation for the asparagine (N) in the amino acid sequence in Figures 1 A and IB. Regions of high identity between Brainiac-5 and the closely related Drosophila Brainiac and human UDP-galactose-2-acetamido-2-deoxy-D-glucose-3-beta- galactosyltransferase (an alignment of these sequences is presented in Figures 2A, 2B, and 2C) are underlined in Figures 1A and IB. These regions are not limiting and are labeled as Conserved Domain (CD)-I, CD-II, CD-III, CD-IV, CD-V, CD- VI, CD- VII, CD- VIII, CD-IX, CD-X, and CD-XI in Figures 1A and IB. Figures 2A, 2B, and 2C show the regions of identity between the Brainiac-5 amino acid sequence and the translation product of the Drosophila melanogaster mRNA for Brainiac (SEQ ID NO:3; GenBank Accession No. U41449), and the human UDP-galactose-2-acetamido-2-deoxy-D-glucose-3-beta-galactosyltransferase (SEQ ID NO:4; GenBank Accession No. Y15014), as determined by the computer program MegAlign (DNA*STAR nucleotide and amino acid sequence analysis package) using the default parameters. Figure 3 shows an analysis of the Brainiac-5 amino acid sequence. Alpha, beta, turn and coil regions; hydrophilicity and hydrophobicity; amphipathic regions; flexible regions; antigenic index and surface probability are shown. In the "Antigenic Index or Jameson-Wolf graph, the positive peaks indicate locations of the highly antigenic regions of the Brainiac-5 polypeptide, i.e., regions from which epitope- bearing peptides of the invention can be obtained. The data presented in Figure 3 are also represented in tabular form in Table I. The columns in Table I are labeled with the headings "Res", "Position", and Roman Numerals I-XIV. The column headings refer to the following features of the amino acid sequence presented in Figure 3 and Table I: "Res": amino acid residue of SEQ ID NO:2 and Figures 1A and IB; "Position": position of the corresponding residue within SEQ ID NO:2 and Figures 1 A and IB; I: Alpha, Regions - Garnier-Robson; II: Alpha, Regions - Chou-Fasman; III: Beta, Regions - Garnier-Robson; IV: Beta, Regions - Chou-Fasman; V: Turn, Regions - Garnier-Robson; VI: Turn, Regions - Chou- Fasman; VII: Coil, Regions - Garnier-Robson; VIII: Hydrophilicity Plot - Kyte- Doolittle; IX: Hydrophobicity Plot - Hopp-Woods; X: Alpha, Amphipathic Regions - Eisenberg; XI: Beta, Amphipathic Regions - Eisenberg; XII: Flexible Regions - Karplus-Schulz; XIII: Antigenic Index - Jameson-Wolf; and XIV: Surface Probability Plot - Emini. Detailed Description The present invention provides isolated nucleic acid molecules comprising, or alternatively consisting of, a polynucleotide encoding a Brainiac-5 polypeptide having the amino acid sequence shown in SEQ ID NO:2, which was determined by sequencing a cloned cDNA. The nucleotide sequence shown in Figures 1 A and IB (SEQ ID NO: l) was obtained by sequencing the HOGCC45 cDNA clone, which was deposited on January 11, 1999 at the American Type Culture Collection, 10801 University Boulevard, Manassas, Virginia 20110-2209, and given ATCC accession number 203572. The deposited clone is contained in the pCMVSPORT 2.0 plasmid (Life Technologies, Inc., Gaithersburg, MD). The Brainiac-5 polypeptides of the present invention share sequence homology with the translation products of the Drosophila melanogaster mRNA which encodes Brainiac (Figure 2; SEQ ID NO:3) human mRNA which encodes UDP-galactose-2- acetamido-2-deoxy-D-glucose-3-beta-galactosyltransferase (Figure 2; SEQ ID NO:4). Drosophila Brainiac is thought to be an important neurogenic secreted molecule that is believed to play a role in the differentiation of embryonic cells into neurons. Thus, it is contemplated that the Brainiac-5 polynucleotides and polypeptides of the invention exert an effect on the differentiation of cells in the early stages of cell and tissue development, and may serve to aid in the differentiation of embryonic cells into dendritic or other immune system cells or neurons or other cells of the nervous system. Nucleic Acid Molecules Unless otherwise indicated, all nucleotide sequences determined by sequencing a DNA molecule herein were determined using an automated DNA sequencer (such as the Model 373 from Applied Biosystems, Inc., Foster City, CA), and all amino acid sequences of polypeptides encoded by DNA molecules determined herein were predicted by translation of a DNA sequence determined as above. Therefore, as is known in the art for any DNA sequence determined by this automated approach, any nucleotide sequence determined herein may contain some errors. Nucleotide sequences determined by automation are typically at least about 90% identical, more typically at least about 95% to at least about 99.9% identical to the actual nucleotide sequence of the sequenced DNA molecule. The actual sequence can be more precisely determined by other approaches including manual DNA sequencing methods well known in the art. As is also known in the art, a single insertion or deletion in a determined nucleotide sequence compared to the actual sequence will cause a frame shift in translation of the nucleotide sequence such that the predicted amino acid sequence encoded by a determined nucleotide sequence will be completely different from the amino acid sequence actually encoded by the sequenced DNA molecule, beginning at the point of such an insertion or deletion. By "nucleotide sequence" of a nucleic acid molecule or polynucleotide is intended, for a DNA molecule or polynucleotide, a sequence of deoxyribonucleotides, and for an RNA molecule or polynucleotide, the corresponding sequence of ribonucleotides (A, G, C and U), where each thymidine deoxyribonucleotide (T) in the specified deoxyribonucleotide sequence is replaced by the ribonucleotide uridine (U). Using the information provided herein, such as the nucleotide sequence in Figures 1A and IB (SEQ ID NO:l), a nucleic acid molecule of the present invention encoding a Brainiac-5 polypeptide may be obtained using standard cloning and screening procedures, such as those for cloning cDNA using mRNA as starting material. Illustrative of the invention, the nucleic acid molecule described in Figures 1 A and IB (SEQ ID NO: 1) was discovered in a cDNA library derived from ovarian tumor cells. Additional clones of the same gene were also identified in cDNA libraries from the following tissues: bone marrow stromal cells and synovial sarcoma cells. The determined nucleotide sequence of the Brainiac-5 cDNA of Figures 1A and IB (SEQ ID NO:l) contains a partial open reading frame encoding a polypeptide of 278 amino acid residues, initiating with a valine codon at nucleotide positions 1-3 of the nucleotide sequence in Figures 1A and IB (SEQ ID NO:l), and a deduced molecular weight of about 30,475 Daltons. The amino acid sequence of the Brainiac-5 polypeptide shown in SEQ ID NO:2 is about 37.7% identical to Drosophila melanogaster mRNA for Brainiac (Figure 2), which can be accessed as GenBank Accession No. U41449. As one of ordinary skill would appreciate, due to the possibilities of sequencing errors discussed above, the actual complete Brainiac-5 polypeptides encoded by the respective deposited cDNA clones, which comprises about 278 amino acids, may be somewhat longer or shorter. More generally, the actual open reading frames comprising Brainiac-5 may be anywhere in the range of ±20 amino acids, more likely in the range of ±10 amino acids, of that predicted from the valine codon at the N-terminus shown in Figures 1A and IB (SEQ ID NO:l). It will further be appreciated that, depending on the analytical criteria used for identifying various functional domains, the exact "address" of a signal sequence or other particular domains of the Brainiac-5 polypeptides may differ slightly from the predicted positions herein. As indicated, nucleic acid molecules of the present invention may be in the form of RNA, such as mRNA, or in the form of DNA, including, for instance, cDNA and genomic DNA obtained by cloning or produced synthetically. The DNA may be double-stranded or single-stranded. Single-stranded DNA or RNA may be the coding strand, also known as the sense strand, or it may be the non-coding strand, also referred to as the anti-sense strand. In specific embodiments, the polynucleotides of the invention are less than 100,000 kb, 50,000 kb, 10,000 kb, 1,000 kb, 500 kb, 400 kb, 350 kb, 300 kb, 250 kb, 200 kb, 175 kb, 150 kb, 125 kb, 100 kb, 75 kb, 50 kb, 40 kb, 30 kb, 25 kb, 20 kb, 15 kb, 10 kb, 7.5 kb, or 5 kb in length. In further embodiments, polynucleotides of the invention comprise at least 15, at least 30, at least 50, at least 100, or at least 250, at least 500, or at least 1000 contiguous nucleotides of Brainiac-5 coding sequence, but consist of less than or equal to 1000 kb, 500 kb, 250 kb, 200 kb, 150 kb, 100 kb, 75 kb, 50 kb, 30 kb, 25 kb, 20 kb, 15 kb, 10 kb, or 5 kb of genomic DNA that flanks the 5' or 3' coding nucleotide set forth in Figures 1A and IB (SEQ ID NO: l). In further embodiments, polynucleotides of the invention comprise at least 15, at least 30, at least 50, at least 100. or at least 250, at least 500, or at least 1000 contiguous nucleotides of Brainiac-5 coding sequence, but do not comprise all or a portion of any Brainiac-5 intron. In another embodiment, the nucleic acid comprising Brainiac-5 coding sequence does not contain coding sequences of a genomic flanking gene (i.e., 5' or 3' to the Brainiac-5 gene in the genome). In other embodiments, the polynucleotides of the invention do not contain the coding sequence of more than 1000, 500, 250, 100, 50, 25, 20, 15, 10, 5, 4, 3, 2, or 1 genomic flanking gene(s). By "isolated" nucleic acid molecule(s) is intended a nucleic acid molecule, DNA or RNA, which has been removed from its native environment. For example, recombinant DNA molecules contained in a vector are considered isolated for the purposes of the present invention. Further examples of isolated DNA molecules include recombinant DNA molecules maintained in heterologous host cells or purified (partially or substantially) DNA molecules in solution. Isolated RNA molecules include in vivo or in vitro RNA transcripts of the DNA molecules of the present invention. Isolated nucleic acid molecules according to the present invention further include such molecules produced synthetically. In another embodiment, an "isolated" nucleic acid molecule does not encompass a chromosome isolated or removed from a cell or a cell lysate (e.g., a "chromosome spread", as in a karyotype). In yet another embodiment, an "isolated" nucleic acid molecule does not encompass a cDNA or genomic library which contains a sequence which encodes Brainiac-5. In further embodiments, an "isolated" nucleic acid molecule does not encompass any collection of vectors which contain exceptionally large DNA, RNA, or cDNA inserts with respect to the Brainiac-5 sequence disclosed herein (for example, cDNA or genomic libraries, or YAC or BAC artificial chromosomes, and the like) which contain a sequence encoding Brainiac-5. Isolated nucleic acid molecules of the present invention include DNA molecules comprising, or alternatively consisting of, an open reading frame (ORF), or comprising a partial ORF, initiating with a valine codon at positions 1-3 of the nucleotide sequence shown in Figures 1A and IB (SEQ ID NO: l). In addition, isolated nucleic acid molecules of the invention include DNA molecules which comprise, or alternatively consist of, a sequence substantially different from those described above but which, due to the degeneracy of the genetic code, still encode Brainiac-5 polypeptides of the invention. In specific embodiments, Brainiac-5 variants in which 5-10, 1-5, or 1-2 amino acids are substituted, deleted, or added in any combination are preferred. Of course, the genetic code and species-specific codon preferences are well known in the art. Thus, it would be routine for one skilled in the art to generate the degenerate variants described above, for instance, to optimize codon expression for a particular host (e.g., change codons in the human mRNA to those preferred by a bacterial host such as E. coli). In another embodiment, the invention provides isolated nucleic acid molecules encoding the Brainiac-5 polypeptide having (i.e., comprising, or alternatively consisting of) an amino acid sequence encoded by the cDNA clone contained in the plasmid deposited as ATCC Deposit No. 203572 on January 11, 1999. Preferably, this nucleic acid molecule will encode the mature polypeptide encoded by the above-described deposited cDNA clone. The invention further provides an isolated nucleic acid molecule having (i.e., comprising, or alternatively consisting of) the nucleotide sequence shown in Figures 1A and IB (SEQ ID NO:l) or the nucleotide sequence of the Brainiac-5 cDNA contained in the above-described deposited clone, or a nucleic acid molecule having (i.e., comprising, or alternatively consisting of) a sequence complementary to one of the above sequences. Such isolated molecules, particularly DNA molecules, are useful, for example, as probes for gene mapping, by in situ hybridization with chromosomes, and for detecting expression of the Brainiac-5 gene in human tissue, for instance, by Northern blot analysis. The present invention is further directed to nucleic acid molecules encoding portions of the nucleotide sequences described herein as well as to fragments of the isolated nucleic acid molecules described herein. In particular, the invention provides a polynucleotide having (i.e., comprising, or alternatively consisting of) a nucleotide sequence representing the portion of SEQ ID NO: 1 which consists of positions 1-977 of SEQ ID NO: 1. Further, the invention includes a polynucleotide comprising, or alternatively consisting of, any portion of at least about 30 nucleotides, preferably at least about 50 nucleotides, of SEQ ID NO: 1 from positions 1 -977 of SEQ ID NO: 1 , excluding the sequences of the following related cDNA clones, and any subfragments therein: HOGCC45RA (SEQ ID NO:5); HTEDM56R (SEQ ID NO:6); HSSET36R (SEQ ID NO:7); HSOBD70R (SEQ ID NO:8); HI 8701 (SEQ ID NO:9); and (SEQ ID NO: 10). Further, the invention includes a polynucleotide comprising, or alternatively consisting of, any portion of at least about 25 nucleotides, preferably at least about 30 < nucleotides, more preferably at least about 40 nucleotides, and even more preferably at least about 50 nucleotides, of SEQ ID NO: 1 from residue 1-600. More preferably, the invention includes a polynucleotide comprising, or alternatively consisting of, nucleotides 1-600; 25-600; 50-600; 75-600; 100-600; 125-600; 150-600; 175-600; 200-600; 225-600; 250-600; 275-600; 300-600; 325-600; 350-600; 375-600; 400-600; 425-600; 450-600; 475-600; 500-600; 525-600; 550-600; 575-600; 1-575; 25-575; 50-575; 75-575; 100-575; 125-575; 150-575; 175-575; 200-575; 225-575; 250-575; 275-575; 300-575; 325-575; 350-575; 375-575; 400-575; 425-575; 450-575; 475-575; 500-575; 525-575; 550-575; 1-550; 25-550; 50-550; 75-550; 100-550; 125-550; 150-550; 175-550; 200-550; 225-550; 250-550; 275-550; 300-550; 325-550; 350-550; 375-550; 400-550; 425-550; 450-550; 475-550; 500-550; 525-550; 1-525; 25-525; 50-525; 75-525; 100-525; 125-525; 150-525; 175-525; 200-525; 225-525; 250-525; 275-525; 300-525; 325-525; 350-525; 375-525; 400-525; 425-525; 450-525; 475-525; 500-525; 1-500; 25-500; 50-500; 75-500; 100-500; 125-500; 150-500; 175-500; 200-500; 225-500; 250-500; 275-500; 300-500; 325-500; 350-500; 375-500; 400-500; 425-500; 450-500; 475-500; 1-475; 25-475; 50-475; 75-475; 100-475; 125-475; 150-475; 175-475; 200-475; 225-475; 250-475; 275-475; 300-475; 325-475; 350-475; 375-475; 400-475; 425-475; 450-475; 1-450; 25-450; 50-450; 75-450; 100-450; 125-450; 150-450; 175-450; 200-450; 225-450; 250-450; 275-450; 300-450; 325-450; 350-450; 375-450; 400-450; 425-450; 1-425; 25-425; 50-425; 75-425; 100-425; 125-425; 150-425; 175-425; 200-425; 225-425; 250-425; 275-425; 300-425; 325-425; 350-425; 375-425; 400-425; 1-400; 25-400; 50-400; 75-400; 100-400; 125-400; 150-400; 175-400; 200-400; 225-400; 250-400; 275-400; 300-400; 325-400; 350-400; 375-400; 1-375; 25-375; 50-375; 75-375; 100-375; 125-375; 150-375; 175-375; 200-375; 225-375; 250-375; 275-375; 300-375; 325-375; 350-375; 1-350; 25-350; 50-350; 75-350; 100-350; 125-350; 150-350; 175-350; 200-350; 225-350; 250-350; 275-350; 300-350; 325-350; 1-325; 25-325; 50-325; 75-325; 100-325; 125-325; 150-325; 175-325; 200-325; 225-325; 250-325; 275-325; 300-325; 1-300; 25-300; 50-300; 75-300; 100-300; 125-300; 150-300; 175-300; 200-300; 225-300; 250-300; 275-300; 1-275; 25-275; 50-275; 75-275; 100-275; 125-275; 150-275; 175-275; 200-275; 225-275; 250-275; 1-250; 25-250; 50-250; 75-250; 100-250; 125-250; 150-250; 175-250; 200-250; 225-250; 1-225; 25-225; 50-225; 75-225; 100-225; 125-225; 150-225; 175-225; 200-225; 1-200; 25-200; 50-200; 75-200; 100-200; 125-200; 150-200; 175-200; 1-175; 25-175; 50-175; 75-175; 100-175; 125-175; 150-175; 1-150; 25-150; 50-150; 75-150; 100-150; 125-150; 1-125; 25-125; 50-125; 75-125; 100-125; 1-100; 25-100; 50-100; 75-100; 1-75; 25-75; 50-75; 1-50; 25-50; and 1-25 of SEQ ID NO. l. Preferably, these fragments encode a polypeptide which has biological activity, and/or a Brainiac-5 functional activity (e.g., activation of the Notch signaling pathway, mediation of protein-protein interactions (e.g., between Brainiac-5 and Su(H) or a human homolog of Su(H)), and/or binding of an antibody specific to Brainiac-5). More generally, by a fragment of an isolated nucleic acid molecule having the nucleotide sequence of the deposited cDNA or the nucleotide sequences shown in Figures 1A and IB (SEQ ID NO:l), is intended fragments at least about 15 nt, and more preferably at least about 20 nt, still more preferably at least about 30 nt, and even more preferably, at least about 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, or 500 nt in length which are useful, for example, as diagnostic probes and primers as discussed herein. Of course, larger fragments 50-300 nt in length are also useful according to the present invention as are fragments corresponding to most, if not all, of the nucleotide sequence of the deposited cDNA or as shown in Figures 1A and IB (SEQ ID NO: 1). By a fragment at least 20 nt in length, for example, is intended fragments which include 20 or more contiguous bases from the nucleotide sequence of the deposited cDNA or the nucleotide sequence as shown in Figures 1A and IB (SEQ ID NO:l). By "about" in the phrase "at least about" is meant the recited value and values that are larger or smaller by several, a few, a small number, 5, 4, 3, 2 or 1. Preferred nucleic acid fragments of the present invention include nucleic acid molecules encoding epitope-bearing portions of the Brainiac-5 polypeptides as identified in Figure 3, and described in more detail below. By "Brainiac-5 functional activity" is meant, for example, activation of the Notch signaling pathway, mediation of protein-protein interactions (e.g., between Brainiac-5 and Su(H) or a human homolog of Su(H)), and/or binding of an antibody specific to Brainiac-5. The functional activity of Brainiac-5 polypeptides, and fragments, variants derivatives, and analogs thereof, can be assayed by various methods. For example, in one embodiment where one is assaying for the ability to bind or compete with full-length Brainiac-5 polypeptide for binding to anti-Brainiac-5 antibody, various immunoassays known in the art can be used, including but not limited to, competitive and non-competitive assay systems using techniques such as radioimmunoassays, ELISA (enzyme linked immunosorbent assay), "sandwich" immunoassays, immunoradiometric assays, gel diffusion precipitation reactions, immunodiffusion assays, in situ immunoassays (using colloidal gold, enzyme or radioisotope labels, for example), western blots, precipitation reactions, agglutination assays (e.g., gel agglutination assays, hemagglutination assays), complement fixation assays, immunofluorescence assays, protein A assays, and immunoelectrophoresis assays, etc. In one embodiment, antibody binding is detected by detecting a label on the primary antibody. In another embodiment, the primary antibody is detected by detecting binding of a secondary antibody or reagent to the primary antibody. In a further embodiment, the secondary antibody is labeled. Many means are known in the art for detecting binding in an immunoassay and are within the scope of the present invention. In another embodiment, where a Brainiac-5 ligand is identified or the ability of a polypeptide fragment, variant or derivative of the invention to multimerize is being evaluated, binding can be assayed, e.g., by means well-known in the art, such as, for example, reducing and non-reducing gel chromatography, protein affinity chromatography, and affinity blotting. See generally, Phizicky, E., et al., 1995, Microbiol. Rev. 59:94-123. In another embodiment, physiological correlates of Brainiac-5 binding to its substrates (signal transduction) can be assayed. Other methods will be known to the skilled artisan and are within the scope of the invention. In additional embodiments, the polynucleotides of the invention encode a polypeptide comprising, or alternatively consisting of, amino acids 7 to 20, 7 to 33, 61 to 83, 105 to 119, 139 to 148, 160 to 171, 187 to 196 of SEQ ID NO:2. Polypeptides encoded by these polynucleotides are also encompassed by the invention. « In additional embodiments, the polynucleotides of the invention encode one, two, three, four or more functional attributes of Brainiac-5. Preferred embodiments of the invention in this regard include fragments that comprise alpha-helix and alpha-helix forming regions ("alpha-regions"), beta-sheet and beta-sheet forming regions ("beta-regions"), turn and turn-forming regions ("turn-regions"), coil and coil-forming regions ("coil-regions"), hydrophilic regions, hydrophobic regions, alpha amphipathic regions, beta amphipathic regions, flexible regions, surface-forming regions and high antigenic index regions of Brainiac-5. Polypeptides encoded by these polynucleotides are also encompassed by the invention. The data representing the structural or functional attributes of Brainiac-5 set forth in Figure 3 and/or Table I, as described above, was generated using the various modules and algorithms of the DNA*STAR set on default parameters. In a preferred embodiment, the data presented in columns VIII, IX, XIII, and XIV of Table I can be used to determine regions of Brainiac-5 which exhibit a high degree of potential for antigenicity. Regions of high antigenicity are determined from the data presented in columns VIII, IX, XIII, and/or IV by choosing values which represent regions of the polypeptide which are likely to be exposed on the surface of the polypeptide in an environment in which antigen recognition may occur in the process of initiation of an immune response. Certain preferred regions in these regards are set out in Figure 3, but may, as shown in Table I, be represented or identified by using tabular representations of the data presented in Figure 3. The DNA*STAR computer algorithm used to generate Figure 3 (set on the original default parameters) was used to present the data in Figure 3 in a tabular format (See Table I). The tabular format of the data in Figure 3 may be used to easily determine specific boundaries of a preferred region. The above-mentioned preferred regions set out in Figure 3 and in Table I include, but are not limited to, regions of the aforementioned types identified by analysis of the amino acid sequence set out in Figures 1 A and IB. As set out in Figure 3 and in Table I, such preferred regions include Garnier-Robson alpha-regions, beta-regions, turn-regions, and coil-regions, Chou-Fasman alpha-regions, beta-regions, and coil-regions, Kyte-Doolittle hydrophilic regions and hydrophobic regions, Eisenberg alpha- and beta-amphipathic regions, Karplus-Schulz flexible regions, Emini surface-forming regions and Jameson-Wolf regions of high antigenic index. Table I tion I II [II IV V VI VII VIII IX XI XII XIII XIV Val 1 A A -0.20 -0.57 0.60 0.81 Ala 2 A A 0.19 -0.21 0.30 0.55 Glu 3 A A 0.69 -0.64 0.60 0.75 Asp 4 A A 1.19 -1.07 0.75 1.97 Phe 5 A A 1.58 -1.71 . F 0.90 3.81 Glu 6 A A 1.84 -1.81 F 0.90 3.81 Arg 7 A A 1.58 -1.31 * = • 0.90 2.31 Arg 8 A A 1.69 -0.67 F 0.90 1.98 Gin 9 A A 1.69 -1.46 * F 0.90 2.24 Ala 10 A A 2.08 -1.06 * 0.75 1.98 Val 11 A A 1.79 -0.57 F 0.90 1.46 Arg 12 A I 3 1.33 0.34 F -0.15 0.88 Gin 13 A I 3 0.63 0.37 * F -0.15 0.87 Thr 14 A r 0.63 0.37 * F 0.40 1.18 Trp 15 A c 0.88 -0.27 * F 1.07 1.04 Gly 16 T c 1.84 0.16 * F 0.99 0.60 Ala 17 T c 0.88 -0.24 * F 1.86 0.81 Glu 18 T c 0.88 -0.09 * F 2.13 0.57 Gly 19 T c 0.84 -0.60 * F 2.70 1.00 Arg 20 B r 0.54 -0.60 * F 2.23 0.98 Val 21 1 ^ B 0.08 -0.60 * F 1.56 0.57 Gin 22 I 3 B -0.19 0.09 * F 0.39 0.48 Gly 23 I 3 B -0.08 0.30 * -0.03 0.18 Ala 24 I 3 B 0.38 0.30 * -0.30 0.48 Leu 25 I 3 B -0.59 -0.34 * 0.30 0.54 Val 26 I 3 B -0.43 -0.10 0.30 0.40 Arg 27 I 3 B -1.24 0.26 -0.30 0.35 Arg 28 I 3 B -1.71 0.44 -0.60 0.35 Val 29 I 3 B -1.47 0.44 -0.60 0.38 Phe 30 I 3 B -1.51 0.23 -0.30 0.19 Leu 31 I 3 B -0.87 0.87 -0.60 0.07 Leu 32 I 3 B -0.87 1.30 -0.60 0.15 Gly 33 I 3 B -1.32 0.66 * -0.60 0.35 Val 34 I 3 T -1.06 0.30 0.10 0.42 Pro 35 I 3 T -0.70 0.11 F 0.25 0.51 Arg 36 T T -0.19 -0.14 F 1.25 0.51 Gly 37 T T 0.28 -0.19 F 1.25 0.92 Ala 38 C 0.28 -0.40 F 1.12 0.59 Gly 39 T c 0.54 -0.40 F 1.59 0.30 Ser 40 T c 0.76 0.10 * F 1.26 0.30 Gly 41 T c 0.64 -0.33 * F 2.13 0.50 Gly 42 T c 0.13 -0.83 F 2.70 0.88 Ala 43 I i 0.38 -0.61 F 2.03 0.49 Asp 44 I i 0.72 -0.57 F 1.76 0.49 Glu 45 I 3 0.68 -1.00 F 1.49 0.85 Val 46 ; I 0.43 -1.00 F 1.22 0.83 Gly 47 1i. 0.89 -1.00 F 0.95 0.50 Glu 48 Ii 1.17 -1.00 F 0.95 0.57 Gly 49 ; V 1.13 -0.51 * F 1.10 1.11 Ala 50 ; I 0.84 -0.66 * F 1.10 1.53 Arg 51 ;i 1.81 -0.17 * F 0.65 0.93 Thr 52 < ; V 1.57 -0.17 * F 0.80 1.83 His 53 ; I A 0.76 -0.10 * 0.45 1.83 Trp 54 ;i. A 0.29 0.09 * -0.30 0.77 Arg 55 ; V A 0.99 0.77 * -0.60 0.44 Ala 56 1 I A 0.29 0.29 * -0.30 0.64 Leu 57 1i A 0.60 0.29 * -0.30 0.61 Leu 58 li. A 0.33 -0.63 * 0.60 0.54 Arg 59 ; I A -0.19 -0.24 * 0.30 0.72 Ala 60 l -. A -0.89 -0.06 * 0.30 0.72 Glu 61 I A -0.54 -0.24 * 0.30 0.88 Ser 62 Ii A -0.32 -0.17 * 0.30 0.70 Table I (continued) Res Position I II ru rv v vi vii viii IX X XI XII XIII XIV Leu 63 A A 0.49 0.33 . -0.30 0.70 Ala 64 A A -0.51 -0.17 . 0.30 0.68 Tyr 65 A A -0.73 0.51 . -0.60 0.35 Ala 66 A A -1.54 0.81 . -0.60 0.35 Asp 67 A A -1.53 0.81 . -0.60 0.29 He 68 A A -1.31 1.23 . -0.60 0.19 Leu 69 A A -1.42 0.97 * -0.60 0.19 Leu 70 A I 3 -1.18 1.26 * -0.60 0.10 Trp 71 A A -0.59 1.26 * -0.60 0.24 Ala 72 A A -0.90 0.57 * -0.60 0.48 Phe 73 A r . -0.71 0.37 . 0.10 0.85 Asp 74 A r . -0.60 0.47 * -0.20 0.70 Asp 75 A r . o.2i 0.34 * . 1 ' 0.25 0.60 Thr 76 A rr . -0.31 0.24 . 0.25 1.11 Phe 77 A A -0.03 0.14 . -0.30 0.55 Phe 78 A A -0.14 0.63 * * -0.60 0.47 Asn 79 A A -0.10 1.31 . * -0.60 0.27 Leu 80 A A -0.10 0.83 * * -0.60 0.63 Thr 81 A A -0.68 0.04 * -0.15 1.25 Leu 82 A A -0.01 -0.06 * 0.30 0.55 Lys 83 A A -0.01 0.04 * * -0.30 0.90 Glu 84 A A -0.82 0.14 * -0.30 0.54 He 85 A A -0.60 0.34 . -0.30 0.54 His 86 A A -0.58 0.16 . -0.30 0.27 Phe 87 A A -0.36 1.07 . -0.60 0.17 Leu 88 A A -0.70 1.57 . -0.60 0.24 Ala 89 A A -1.29 1.27 . * -0.60 0.24 Trp 90 A A -1.10 1.27 . -0.60 0.27 Ala 91 A A -1.73 1.27 . -0.60 0.29 Ser 92 A A -1.24 1.16 . -0.60 0.15 Ala 93 A T -0.43 1.09 . -0.20 0.23 Phe 94 A T -0.70 0.17 * * 0.10 0.37 Cys 95 I 3 1 P . -0.30 0.31 * * 0.10 0.21 Pro 96 T 1 -0.41 -0.07 * * 1.10 0.40 Asp 97 T 1 P . -0.97 0.21 * * 0.50 0.40 Val 98 A 1 -1.08 0.07 * * 0.10 0.55 Arg 99 I 3 B -0.33 0.29 * -0.30 0.31 Phe 100 E i B -0.01 -0.14 * * 0.64 0.37 Val 101 I 3 B 0.20 0.29 * * 0.38 0.49 Phe 102 I 3 1 -0.39 -0.36 * * 1.72 0.42 Lys 103 A 1 0.47 0.14 * * E Λ 1.61 0.49 Gly 104 T 1 -0.50 -0.64 * * E 3.40 1.11 Asp 105 T 1 -0.50 -0.64 . * E 2.91 0.95 Ala 106 A B -0.50 -0.64 * * E 1 1.77 0.41 Asp 107 A B 0.20 0.00 * * 0.38 0.31 Val 108 I ϊ B -0.70 -0.03 * * 0.64 0.30 Phe 109 Ei B -0.70 0.61 * * -0.60 0.22 Val 110 Ξ 5 B -0.70 0.54 * * -0.60 0.13 Asn 111 Ei 1 -0.92 0.94 * * -0.20 0.28 Val 112 Ii 1 -1.73 0.99 * -0.20 0.27 Gly 113 1 C -0.88 0.89 * 0.00 0.30 Asn 114< A 1 -0.88 0.24 * 0.10 0.32 Leu 115 A I V -0.83 0.63 * -0.60 0.37 Leu 116 A /i -1.42 0.67 * -0.60 0.31 Glu 117 ; _. E . -0.78 0.74 * -0.60 0.19 Phe 118 ϊ _ Ei -0.32 0.77 . -0.60 0.37 Leu 119 I _ E . -0.32 0.09 . -0.30 0.87 Ala 120 ϊ _ Ei 0.28 -0.60 . 0.60 0.84 Pro 121 A _ 0.50 -0.17 . . I ' 0.60 1.49 Arg 122 _ T 0.50 -0.46 . . F ' 1.00 1.83 Asp 123 A 1 1.20 -0.74 * . E 1.30 3.14 Table I (continued) Res Position I II III IV V VI VII VIII IX X XI XII XIII XIV Pro 124 A rr . 1.20 -1.24 * . F 1.30 3.39 Ala 125 A r . 0.98 -0.99 * . = • 1.30 1.43 Gin 126 A r . 0.60 -0.30 * F 0.85 0.70 Asp 127 A B 0.14 0.20 * . ? -0.15 0.46 Leu 128 A A 0.14 0.20 . -0.30 0.45 Leu 129 A A -0.50 -0.30 0.30 0.43 Ala 130 A A -0.80 -0.06 0.30 0.19 Gly 131 1 . . B -1.66 0.63 -0.60 0.16 Asp 132 1 \ . . B -1.69 0.59 -0.60 0.15 Val 133 B B -1.47 0.40 * -0.60 0.20 He 134 B B -0.54 0.40 * * -0.60 0.20 Val 135 B B -0.17 -0.03 * * 0.30 0.24 His 136 B B -0.71 0.40 * * -0.60 0.50 Ala 137 B B -0.60 0.44 * * -0.60 0.50 Arg 138 B B -0.06 -0.24 . 0.45 1.31 Pro 139 B B 0.94 -0.40 . * F 0.60 1.39 He 140 B V 1.21 -0.90 . * F 1.30 2.69 Arg 141 B B 0.94 -0.90 * * F 1.18 1.39 Thr 142 B B 1.58 -0.51 * * F 1.46 1.20 Arg 143 B B 1.22 -0.94 * * F 1.74 3.44 Ala 144 B B T 1.19 -0.87 . * F 2.42 2.75 Ser 145 T 1 P . 1.19 -0.11 . * F 2.80 2.98 Lys 146 T 1 P . 0.87 0.09 . * 1.77 1.07 Tyr 147 B 1 P . 1.18 0.51 * 0.79 1.63 Tyr 148 B 1 P . 0.48 0.01 * 0.81 2.11 He 149 B 0.21 0.13 . 0.33 1.07 Pro 150 B 0.27 0.77 . -0.40 0.51 Glu 151 B -0.12 0.77 * -0.40 0.51 Ala 152 B -0.69 0.44 * -0.40 0.71 Val 153 B -0.66 0.44 * -0.40 0.38 Tyr 154 B -0.36 0.44 * -0.40 0.34 Gly 155 B -0.39 0.94 . -0.40 0.34 Leu 156 B -0.60 1.20 -0.40 0.72 Pro 157 B -0.60 0.99 -0.40 0.71 Ala 158 B 0.01 0.73 -0.40 0.72 Tyr 159 B 1 -0.33 1.06 -0.05 1.37 Pro 160 B 1 -0.33 0.87 -0.20 0.90 Ala 161 B 1 0.13 0.87 -0.20 0.88 Tyr 162 B 1 -0.00 0.80 -0.20 0.56 Ala 163 B 0.24 0.47 -0.40 0.36 Gly 164 T 1 -0.21 0.47 I - 0.35 0.35 Gly 165 T 1 -0.86 0.76 I - 0.35 0.19 Gly 166 B 1 -1.08 0.64 I - -0.05 0.14 Gly 167 B 1 -1.13 0.83 I -0.05 0.12 Phe 168 B -0.89 0.79 -0.40 0.16 Val 169 B -1.13 0.79 -0.40 0.16 Leu 170 B 1 -1.10 0.86 -0.20 0.16 Ser 171 B 1 -1.57 0.91 -0.20 0.27 Gly 172 B 1 -1.26 0.81 * I -0.05 0.30 Ala 173 ϊ -. 1 -0.44 0.67 * I -0.05 0.50 Thr 174 -?i. A -0.40 -0.01 . 0.30 0.73 Leu 175" ϊi A -0.18 0.29 . -0.30 0.61 His 176 -? i A -0.22 0.36 * -0.30 0.61 Arg 177 A B -0.47 0.29 * -0.30 0.42 Leu 178 ti. A -0.54 0.30 * -0.30 0.51 Ala 179 / _ A -0.82 0.19 * -0.30 0.20 Gly 180 i=i A -0.01 0.19 * -0.30 0.10 Ala 181 ; A -0.83 0.59 * * -0.60 0.22 Cys 182 Ii. A -0.94 0.54 . -0.60 0.16 Ala 183 t _ A -0.94 0.04 . * -0.30 0.28 Table I (continued) Res Position r n EH IV V VI VII VIII IX X XI KIT XIII XIV Gin 184 A A -1.06 0.30 . * -0.30 0.23 Val 185 A B -0.92 0.59 -0.60 0.37 Glu 186 A B -1.22 0.44 * -0.60 0.56 Leu 187 A B -0.56 0.63 -0.60 0.23 Phe 188 A B 0.03 0.23 -0.30 0.51 Pro 189 A B -0.82 -0.41 0.30 0.49 He 190 A A B -0.67 0.23 -0.30 0.45 Asp 191 A A B -1.48 0.33 F -0.15 0.45 Asp 192 A A B -1.01 0.23 F -0.15 0.24 Val 193 A A B -0.91 0.23 -0.30 0.34 Phe 194 A A B -1.37 0.16 -0.30 0.20 Leu 195 A A B -1.29 0.73 -0.60 0.06 Gly 196 A A B -1.29 1.41 -0.60 0.07 Met 197 A A B -1.18 1.17 -0.60 0.14 Cys 198 A A B -1.13 0.39 * * -0.30 0.34 Leu 199 A A B -0.32 0.39 * * -0.30 0.28 Gin 200 A 1 3 B -0.32 -0.04 . * 0.30 0.56 Arg 201 A I 3 B -0.29 0.03 . * -0.30 0.85 Leu 202 A I 3 B 0.10 -0.06 . * 0.69 1.49 Arg 203 A I 3 B 0.77 -0.31 * * 0.93 1.33 Leu 204 B C 1.37 -0.71 . * 1.67 1.18 Thr 205 T C 1.33 -0.29 . * F 2.16 2.21 Pro 206 T C 1.01 -0.47 . * F 2.40 1.54 Glu 207 T C 1.23 -0.04 * * F 2.16 2.88 Pro 208 T C 0.42 -0.23 * * F 1.92 2.02 His 209 C 1.34 0.07 * * F 0.88 1.13 Pro 210 C 1.34 -0.36 * * 1.09 1.28 Ala 211 I 3 B 1 P 0.86 0.13 * * 0.25 1.19 Phe 212 I 3 B 0.51 0.49 * -0.60 0.76 Arg 213 I 3 B -0.17 0.41 * -0.60 0.49 Thr 214 I 3 B -0.34 0.67 * -0.60 0.34 Phe 215 I 3 B -0.13 0.60 . -0.60 0.60 Gly 216 B 1 P 0.24 0.21 0.10 0.53 He 217 B C 0.64 0.64 F -0.25 0.57 Pro 218 B C -0.06 0.54 F -0.25 0.88 Gin 219 1 C -0.33 0.26 F 0.45 0.90 Pro 220 1 C 0.16 0.33 F 0.60 1.30 Ser 221 1 C 0.47 0.07 F 0.60 1.30 Ala 222 E 3 1 0.54 0.14 0.25 1.02 Ala 223 I 3 0.46 0.43 -0.40 0.54 Pro 224 E 3 0.14 0.39 -0.10 0.54 His 225 r 3 -0.34 0.49 -0.40 0.78 Leu 226 E 3 -0.04 0.77 -0.40 0.67 Ser 227 E 3 0.33 0.27 E 0.05 0.72 Thr 228 1 0.26 0.27 E 0.45 0.82 Phe 229 I . -0.23 0.34 E 0.05 0.53 Asp 230 E i 1 -0.44 0.44 * E ' -0.05 0.34 Pro 231 T 1 0.48 0.81 * 0.20 0.37 Cys 232 T 1 0.78 0.33 * 0.50 0.84 Phe 233 E . . . 1 0.28 -0.46 * 0.70 0.87 Tyr 234 ϊ _ 0.12 0.23 . -0.10 0.47 Arg 235 / _ B -0.73 0.44 * -0.60 0.65 Glu 236 I I B -1.38 0.51 * -0.60 0.55 Leu 237 ϊ .. B -0.74 0.37 * -0.30 0.26 Val 238 E 5 B -0.39 0.11 * -0.30 0.18 Val 239 Ei B -0.96 0.54 . -0.60 0.10 Val 240 Ei B -1.37 1.23 . -0.60 0.10 His 241 I _. B -1.96 0.93 . -0.60 0.19 Gly 242 ts. B -1.73 0.79 . -0.60 0.26 Leu 243 _? _ A -0.88 0.64 . -0.60 0.35 Table I (continued) Res Position r ii III iv v vi vn VIII IX X XI XII XIII XIV Ser 244 A A -0.91 0.00 -0.30 0.43 Ala 245 A A -0.34 0.19 . -0.30 0.30 Ala 246 A A B -1.12 0.67 -0.60 0.39 Asp 247 A A B -1.38 0.67 -0.60 0.24 He 248 A A B -0.86 0.90 * -0.60 0.23 Trp 249 A A B -0.44 1.31 * -0.60 0.24 Leu 250 A A B -0.67 0.81 * * -0.60 0.28 Met 251 A A B -0.89 1.50 -0.60 0.33 Trp 252 A A B -0.92 1.50 * * -0.60 0.26 Arg 253 A I 3 B -0.38 1.09 -0.60 0.43 Leu 254 A B T -0.30 0.83 -0.20 0.43 Leu 255 A B T 0.48 0.64 -0.20 0.64 His 256 A B T 0.73 0.23 0.10 0.44 Gly 257 T C 0.81 0.66 * * F 0.15 0.53 Pro 258 T T 0.11 0.40 * . F 0.35 0.99 His 259 T T 0.26 0.21 F 0.65 0.74 Gly 260 T C 0.48 0.29 F 0.45 0.40 Pro 261 T 0.48 0.36 F 0.45 0.26 Ala 262 T 0.61 0.43 0.00 0.26 Cys 263 E 3 0.82 0.36 -0.10 0.41 Ala 264 E 3 0.64 0.33 -0.10 0.46 His 265 I 3 T 0.13 0.33 0.10 0.70 Pro 266 I 3 T -0.24 0.47 F -0.05 0.97 Gin 267 E 3 T -0.24 0.40 F -0.05 0.97 Pro 268 E 3 T 0.08 0.40 F -0.05 0.72 Val 269 E 3 0.46 0.33 -0.10 0.46 Ala 270 E 3 -0.21 0.33 -0.10 0.41 Ala 271 E 3 . 0.00 0.71 -0.40 0.23 Gly 272 E 3 T -0.29 0.69 * -0.20 0.54 Pro 273 Ei T -0.08 0.96 * -0.20 0.56 Phe 274 1 T 0.48 0.46 * 0.20 0.92 Gin 275 1 T 0.68 0.34 * 0.65 1.25 Trp 276 E 3 0.88 0.34 * 0.05 1.03 Asp 277 c 0.83 0.34 * 0.25 1.53 Ser 278 c 0.66 -0.01 * 0.85 1.13 Among highly preferred fragments in this regard are those that comprise, or alternatively consist of, regions of Brainiac-5 that combine several structural features, such as several of the features set out above. In another embodiment, the invention provides an isolated nucleic acid molecule comprising a polynucleotide which hybridizes under stringent hybridization conditions to a portion of the polynucleotide in a nucleic acid molecule of the invention described above, for instance, the sequence complementary to the coding sequence and/or noncoding sequence depicted in SEQ ID NO:l, the Brainiac-5 cDNA clone contained in ATCC Deposit No. 203572, or fragments (such as, for example, the open reading frame or a fragment thereof) of these sequences, as described herein. By "stringent hybridization conditions" is intended overnight incubation at 42°C in a solution comprising: 50% formamide, 5x SSC (750 mM NaCl, 75 mM trisodium citrate), 50 mM sodium phosphate (pH 7.6), 5x Denhardt's solution, 10% dextran sulfate, and 20 μg/ml denatured, sheared salmon sperm DNA, followed by washing the filters in 0. lx SSC at about 65°C. By a polynucleotide which hybridizes to a "portion" of a polynucleotide is intended a polynucleotide (either DNA or RNA) hybridizing to at least about 15 nucleotides (nt), and more preferably at least about 20 nt, still more preferably at least about 30 nt, and even more preferably about 30-70 (e.g., 50) nt of the reference polynucleotide. These are useful as diagnostic probes and primers as discussed above and in more detail below. By a portion of a polynucleotide of "at least 20 nt in length," for example, is intended 20 or more contiguous nucleotides from the nucleotide sequence of the reference polynucleotide (e.g., the deposited cDNA or the nucleotide sequence as shown in Figures 1A and IB (SEQ ID NO:l). Of course, a polynucleotide which hybridizes only to a poly A sequence (such as the 3' terminal poly (A) tract of the Brainiac-5 cDNA shown in Figures 1 A and IB (SEQ ID NO: 1), or to a complementary stretch of T (or U) residues, would not be included in a polynucleotide of the invention used to hybridize to a portion of a nucleic acid of the invention, since such a polynucleotide would hybridize to any nucleic acid molecule containing a poly (A) stretch or the complement thereof (e.g., practically any double- stranded cDNA clone). As indicated, nucleic acid molecules of the present invention which encode a Brainiac-5 polypeptide may include, but are not limited to those encoding the amino acid sequence of the mature polypeptide, by itself; and the coding sequence for the mature polypeptide and additional sequences, such as those encoding a leader or secretory sequence, such as a pre-, or pro- or prepro- protein sequence; the coding sequence of the mature polypeptide, with or without the aforementioned additional coding sequences. Also encoded by nucleic acids of the invention are the above polypeptide sequences together with additional, non-coding sequences, including for example, but not limited to introns and non-coding 5' and 3' sequences, such as the transcribed, non-translated sequences that play a role in transcription, mRNA processing, including splicing and polyadenylation signals, for example - ribosome binding and stability of mRNA; an additional coding sequence which codes for additional amino acids, such as those which provide additional functionalities. Thus, the sequence encoding the polypeptide may be fused to a marker sequence, such as a sequence encoding a peptide which facilitates purification of the fused polypeptide or which may function in secretion of the fused polypeptide from a cell. In certain preferred embodiments of this aspect of the invention, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, CA, 91311), among others, many of which are commercially available. As described by Gentz and colleagues (Proc. Natl. Acad. Sci. USA 86:821-824 (1989)), for instance, hexa-histidine provides for convenient purification of the fusion protein. The "HA" tag is another peptide useful for purification which corresponds to an epitope derived from the influenza hemagglutinin protein, which has been described by Wilson and coworkers (Cell 37:767 (1984)). As discussed below, other such fusion proteins include the Brainiac-5 polypeptides fused to Fc at the N- or C-terminus. The present invention further relates to variants of the nucleic acid molecules of the present invention, which encode portions, analogs or derivatives of the Brainiac-5 polypeptides. Variants may occur naturally, such as a natural allelic variant. By an "allelic variant" is intended one of several alternate forms of a gene occupying a given locus on a chromosome of an organism (Genes II, Lewin, B., ed., John Wiley & Sons, New York (1985)). Non-naturally occurring variants may be produced using art-known mutagenesis techniques, which include, but are not limited to ohgonucleotide mediated mutagenesis, alanine scanning, PCR mutagenesis, site directed mutagenesis (see e.g., Carter et al., Nucl. Acids Res. 13:4331 (1986); and Zoller et al., Nucl. Acids Res. 10:6487 (1982)), cassette mutagenesis (see e.g., Wells et al, Gene 34:315 (1985)), restriction selection mutagenesis (see e.g., Wells er al., Philos. Trans. R. Soc. London SerA 317:415 (1986)). Such variants include those produced by nucleotide substitutions, deletions or additions. The substitutions, deletions or additions may involve one or more nucleotides. The variants may be altered in coding regions, non-coding regions, or both. Alterations in the coding regions may produce conservative or non-conservative amino acid substitutions, deletions or additions. Especially preferred among these are silent substitutions, additions and deletions, which do not alter the properties and activities of the Brainiac-5 polypeptides or portions thereof. Also especially preferred in this regard are conservative substitutions. Additional embodiments of the invention are directed to isolated nucleic acid molecules comprising, or alternatively consisting of, a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide (e.g., a Brainiac-5 fragment described herein) having an amino acid sequence which contains at least one conservative amino acid substitution, but not more than 50 conservative amino acid substitutions, even more preferably, not more than 40 conservative amino acid substitutions, still more preferably, not more than 30 conservative amino acid substitutions, and still even more preferably, not more than 20 conservative amino acid substitutions, 10-20 conservative amino acid substitutions, 5-10 conservative amino acid substitutions, 1-5 conservative amino acid substitutions, 3-5 conservative amino acid substitutions, or 1-3 conservative amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide to have an amino acid sequence which contains not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 conservative amino acid substitutions. Most highly preferred are nucleic acid molecules encoding a mature polypeptide having the amino acid sequence shown in SEQ ID NO:2 or the mature Brainiac-5 amino acid sequence encoded by the deposited cDNA clone. Thus, one embodiment of the invention provides an isolated nucleic acid molecule comprising, or alternatively consisting of, a polynucleotide having a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the Brainiac-5 polypeptide having the complete amino acid sequence in SEQ ID NO:2 (i.e., positions 1 to 278 of SEQ ID NO:2); (b) a nucleotide sequence encoding the Brainiac-5 polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; (c) a nucleotide sequence encoding the mature Brainiac-5 polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; and (d) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b) or (c), above. Polypeptides encoded by these nucleic acid molecules are also encompassed by the invention. Further embodiments of the invention include isolated nucleic acid molecules that comprise, or alternatively consist of, a polynucleotide having a nucleotide sequence at least 90% identical, and more preferably at least 92%, 95%, 96%, 97%, 98% or 99% identical, to any of the nucleotide sequences in (a), (b), (c) or (d), above, or a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide in (a), (b), (c) or (d), above. This polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues. An additional nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a Brainiac-5 polypeptide having an amino acid sequence in (a), (b) or (c), above. A further nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide having an amino acid sequence which contains at least one conservative amino acid substitution, but not more than 50 conservative amino acid substitutions, even more preferably, not more than 40 conservative amino acid substitutions, still more preferably, not more than 30 conservative amino acid substitutions, and still even more preferably, not more than 20 conservative amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a polynucleotide which encodes the amino acid sequence of a Brainiac-5 polypeptide to have an amino acid sequence which contains not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 conservative amino acid substitutions. Polypeptides encoded by these nucleic acid molecules are also encompassed by the invention. The present invention also relates to recombinant vectors, which include the isolated nucleic acid molecules of the present invention, and to host cells containing the recombinant vectors, as well as to methods of making such vectors and host cells and for using them for production of Brainiac-5 polypeptides or peptides by recombinant techniques. In one embodiment of the invention, by a polynucleotide having a nucleotide sequence at least, for example, 95% "identical" to a reference nucleotide sequence encoding a Brainiac-5 polypeptide is intended that the nucleotide sequence of the polynucleotide is identical to the reference sequence except that the polynucleotide sequence may include up to five point mutations per each 100 nucleotides of the reference nucleotide sequences encoding the Brainiac-5 polypeptides. In other words, to obtain a polynucleotide having a nucleotide sequence at least 95% identical to a reference nucleotide sequence, up to 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or a number of nucleotides up to 5% of the total nucleotides in the reference sequence may be inserted into the reference sequence. These mutations of the reference sequence may occur at the 5' or 3' terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence. As a practical matter, whether any particular nucleic acid molecule, or a portion or fragment thereof, is at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to, for instance, the nucleotide sequences shown in Figures 1A and IB or to the nucleotides sequence of the deposited cDNA clone can be determined conventionally using known computer programs such as the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, WI 53711). Bestfit uses the local homology algorithm of Smith and Waterman to find the best segment of homology between two sequences (Advances in Applied Mathematics 2:482-489 (1981)). When using Bestfit or any other sequence alignment program to determine whether a particular sequence is, for instance, 95% identical to a reference sequence according to the present invention, the parameters are set, of course, such that the percentage of identity is calculated over the full length of the reference nucleotide sequence and that gaps in homology of up to 5% of the total number of nucleotides in the reference sequence are allowed. A preferred method for determining the best overall match between a query sequence (a sequence of the present invention) and a subject sequence, also referred to as a global sequence alignment, can be determined using the FASTDB computer program based on the algorithm of Brutlag and colleagues (Comp. App. Biosci. 6:237-245 (1990)). In a sequence alignment the query and subject sequences are both DNA sequences. An RNA sequence can be compared by converting U's to T's. The result of said global sequence alignment is in percent identity. Preferred parameters used in a FASTDB alignment of DNA sequences to calculate percent identity are: Matrix=Unitary, k-tuple=4, Mismatch Penalty=l, Joining Penal ty=30, Randomization Group Length=0, Cutoff Score=l, Gap Penalty=5, Gap Size Penalty 0.05, Window Size=500 or the length of the subject nucleotide sequence, whichever is shorter. If the subject sequence is shorter than the query sequence because of 5' or 3' deletions, not because of internal deletions, a manual correction must be made to the results. This is because the FASTDB program does not account for 5' and 3' truncations of the subject sequence when calculating percent identity. For subject sequences truncated at the 5' or 3' ends, relative to the query sequence, the percent identity is corrected by calculating the number of bases of the query sequence that are 5' and 3' of the subject sequence, which are not matched/aligned, as a percent of the total bases of the query sequence. Whether a nucleotide is matched/aligned is determined by results of the FASTDB sequence alignment. This percentage is then subtracted from the percent identity, calculated by the above FASTDB program using the specified parameters, to arrive at a final percent identity score. This corrected score is what is used for the purposes of the present invention. Only bases outside the 5' and 3' bases of the subject sequence, as displayed by the FASTDB alignment, which are not matched/aligned with the query sequence, are calculated for the purposes of manually adjusting the percent identity score. For example, a 90 base subject sequence is aligned to a 100 base query sequence to determine percent identity. The deletions occur at the 5' end of the subject sequence and therefore, the FASTDB alignment does not show a matched/alignment of the first 10 bases at 5' end. The 10 unpaired bases represent 10% of the sequence (number of bases at the 5' and 3' ends not matched/total number of bases in the query sequence) so 10% is subtracted from the percent identity score calculated by the FASTDB program. If the remaining 90 bases were perfectly matched the final percent identity would be 90%. In another example, a 90 base subject sequence is compared with a 100 base query sequence. This time the deletions are internal deletions so that there are no bases on the 5' or 3' of the subject sequence which are not matched/aligned with the query. In this case the percent identity calculated by FASTDB is not manually corrected. Once again, only bases 5' and 3' of the subject sequence which are not matched/aligned with the query sequence are manually corrected for. No other manual corrections are to made for the purposes of the present invention. The present application is directed to nucleic acid molecules, comprising or alternatively consisting of, a polynucleotide sequence at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence shown in Figures 1A and IB (SEQ ID NO:l) or to the nucleic acid sequence of the deposited cDNA, irrespective of whether they encode a polypeptide having Brainiac-5 activity. This is because even where a particular nucleic acid molecule does not encode a polypeptide having Brainiac-5 activity, one of skill in the art would still know how to use the nucleic acid molecule, for instance, as a hybridization probe or a polymerase chain reaction (PCR) primer. Uses of the nucleic acid molecules of the present invention that do not encode a polypeptide having Brainiac-5 activity include, inter alia, (1) isolating the Brainiac-5 gene or allelic variants thereof in a cDNA library; (2) in situ hybridization (e.g., "FISH") to metaphase chromosomal spreads to provide precise chromosomal location of the Brainiac-5 gene, as described by Verma and colleagues (Human Chromosomes: A Manual of Basic Techniques, Pergamon Press, New York (1988)); and Northern Blot analysis for detecting Brainiac-5 mRNA expression in specific tissues. Preferred, however, are nucleic acid molecules having (i.e., comprising, or alternatively consisting of, sequences at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence shown in Figures 1A and IB (SEQ ID NO: 1) or to the nucleic acid sequence of the deposited cDNA which do, in fact, encode a polypeptide having Brainiac-5 polypeptide functional activity. By "a polypeptide having Brainiac-5 polypeptide functional activity" is intended polypeptides exhibiting activity similar, but not necessarily identical, to an activity of the mature Brainiac-5 polypeptide of the invention, as measured in a particular biological assay. For example, the Brainiac-5 polypeptides of the present invention modulate cellular growth and differentiation. Thus, biological activity of Brainiac-5 polypeptides can be examined in organ culture assays or in colony assay systems in agarose culture. Stimulation or inhibition of cellular proliferation may be measured by a variety of assays. For observing cell growth inhibition, one can use a solid or liquid medium. In a solid medium, cells undergoing growth inhibition can easily be selected from the subject cell group by comparing the sizes of colonies formed. In a liquid medium, growth inhibition can be screened by measuring culture broth turbidity or incorporation of labeled thymidine in DNA. Typically, the incorporation of a nucleoside analog into newly synthesized DNA is employed to measure proliferation (i.e., active cell growth) in a population of cells. For example, bromodeoxyuridine (BrdU) can be employed as a DNA labeling reagent and anti-BrdU mouse monoclonal antibody (clone BMC 9318 IgG,) can be employed as a detection reagent. This antibody binds only to cells containing DNA which has incorporated bromodeoxyuridine. A number of detection methods may be used in conjunction with this assay including immunofluorescence, immunohistochemical, ELISA, and colorimetric methods. Kits that include bromodeoxyuridine (BrdU) and anti-BrdU mouse monoclonal antibody are commercially available from Boehringer Mannheim (Indianapolis, IN). The effect upon cellular differentiation can be measured by contacting embryonic cells with various amounts of a Brainiac-5 polypeptide and observing the effect upon differentiation of the embryonic cells. Tissue-specific antibodies and microscopy may be used to identify the resulting cells. Brainiac-5 polypeptides modulate immune and/or nervous system cell proliferation and differentiation in a dose-dependent manner in the above-described assays. Thus, "a polypeptide having Brainiac-5 polypeptide activity" includes polypeptides that also exhibit any of the same growth and differentiation regulating activities in the above-described assays in a dose-dependent manner. Although the degree of dose-dependent activity need not be identical to that of the Brainiac-5 polypeptide, preferably, "a polypeptide having Brainiac-5 polypeptide activity" will exhibit substantially similar dose-dependence in a given activity as compared to the Brainiac-5 polypeptide (i.e., the candidate polypeptide will exhibit greater activity or not more than about 25-fold less and, preferably, not more than about tenfold less activity relative to the reference Brainiac-5 polypeptide). Of course, due to the degeneracy of the genetic code, one of ordinary skill in the art will immediately recognize that a large number of the nucleic acid molecules having a sequence at least 90%, 92%, 95%, 96%, 97%, 98%, or 99% identical to the nucleic acid sequence of the deposited cDNA or the nucleic acid sequence shown in Figures 1A and IB (SEQ ID NO: l) will encode a polypeptide "having Brainiac-5 polypeptide functional activity." In fact, since degenerate variants of these nucleotide sequences all encode the same polypeptide, this will be clear to the skilled artisan even without performing the above described comparison assay. It will be further recognized in the art that, for such nucleic acid molecules that are not degenerate variants, a reasonable number will also encode a polypeptide having Brainiac-5 polypeptide activity. This is because the skilled artisan is fully aware of amino acid substitutions that are either less likely or not likely to significantly effect polypeptide function (e.g., replacing one aliphatic amino acid with a second aliphatic amino acid), as further described below. Vectors and Host Cells The present invention also relates to vectors which include the isolated DNA molecules of the present invention, host cells which are genetically engineered with the recombinant vectors, and the production of Brainiac-5 polypeptides or fragments thereof by recombinant techniques. The vector may be, for example, a phage, plasmid, viral or retroviral vector. Retroviral vectors may be replication competent or replication defective. In the latter case, viral propagation generally will occur only in complementing host cells. The polynucleotides may be joined to a vector containing a selectable marker for propagation in a host. Generally, a plasmid vector is introduced in a precipitate, such as a calcium phosphate precipitate, or in a complex with a charged lipid. If the vector is a virus, it may be packaged in vitro using an appropriate packaging cell line and then transduced into host cells. The DNA insert should be operatively linked to an appropriate promoter, such as the phage lambda PL promoter, the E. coli lac, trp, phoA and tac promoters, the SV40 early and late promoters and promoters of retroviral LTRs, to name a few. Other suitable promoters will be known to the skilled artisan. The expression constructs will further contain sites for transcription initiation, termination and, in the transcribed region, a ribosome binding site for translation. The coding portion of the transcripts expressed by the constructs will preferably include a translation initiating codon at the beginning and a termination codon (UAA, UGA or UAG) appropriately positioned at the end of the polypeptide to be translated. As indicated, the expression vectors will preferably include at least one selectable marker. Such markers include dihydrofolate reductase, G418 or neomycin resistance for eukaryotic cell culture and tetracycline, kanamycin or ampicillin resistance genes for culturing in E. coli and other bacteria. Representative examples of appropriate hosts include, but are not limited to, bacterial cells, such as E. coli, Streptomyces and Salmonella typhimuήum cells; fungal cells, such as yeast cells (e.g., Saccharomyces cerevisiae or Pichia pastoris (ATCC Accession No. 201178)); insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animal cells such as CHO, COS, 293 and Bowes melanoma cells; and plant cells. Appropriate culture mediums and conditions for the above-described host cells are known in the art. Vectors preferred for use in bacteria include pHE4-5 (ATCC Accession No. 209311; and variations thereof), pQE70, pQE60 and pQE-9 (QIAGEN, Inc., supra); pBS vectors, Phagescript vectors, Bluescript vectors, pNH8A, pNH16a, pNH18A, pNH46A (Stratagene); and ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 (Pharmacia). Preferred expression vectors for use in yeast systems include, but are not limited to, pYES2, pYDl, pTEFl/Zeo, pYES2/GS, pPICZ, pGAPZ, pGAPZalpha, pPIC9, pPIC3.5, pHIL-D2, pHIL-Sl, pPIC3.5K, pPIC9K, and PAO815 (all available from Invitrogen, Carlsbad, CA). Among preferred eukaryotic vectors are pWLNEO, pSV2CAT, pOG44, pXTl, and pSG (Stratagene); and pSVK3, pBPV, pMSG and pSVL (Pharmacia). Other suitable vectors will be readily apparent to the skilled artisan. Following transformation of a suitable host strain and growth of the host strain to an appropriate cell density, the selected promoter is induced by appropriate means (e.g., temperature shift or chemical induction) and cells are cultured for an additional period. Cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification. Microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents, such methods are well know to those skilled in the art. In one embodiment, the yeast Pichia pastoris is used to express Brainiac-5 protein in a eukaryotic system. Pichia pastoris is a methylotrophic yeast which can metabolize methanol as its sole carbon source. A main step in the methanol metabolization pathway is the oxidation of methanol to formaldehyde using O 2 . This reaction is catalyzed by the enzyme alcohol oxidase. In order to metabolize methanol as its sole carbon source, Pichia pastoris must generate high levels of alcohol oxidase due, in part, to the relatively low affinity of alcohol oxidase for O 2 . Consequently, in a growth medium depending on methanol as a main carbon source, the promoter region of one of the two alcohol oxidase genes (AOXI) is highly active. In the presence of methanol, alcohol oxidase produced from the AOXI gene comprises up to approximately 30% of the total soluble protein in Pichia pastoris. See, Ellis, S.B., et al, Mol. Cell. Biol. 5: 1111-21 (1985); Koutz, P.J, et al, Yeast 5: 167-77 (1989); Tschopp, J.F., et al, Nucl. Acids Res. 15:3859-76 (1987). Thus, a heterologous coding sequence, such as, for example, a Brainiac-5 polynucleotide of the present invention, under the transcriptional regulation of all or part of the AOXI regulatory sequence is expressed at exceptionally high levels in Pichia yeast grown in the presence of methanol. In one example, the plasmid vector pPIC9K is used to express DNA encoding a Brainiac-5 polypeptide of the invention, as set forth herein, in a Pichea yeast system essentially as described in "Pichia Protocols: Methods in Molecular Biology," D.R. Higgins and J. Cregg, eds. The Humana Press, Totowa, NJ, 1998. This expression vector allows expression and secretion of a Brainiac-5 protein of the invention by virtue of the strong AOXI promoter linked to the Pichia pastoris alkaline phosphatase (PHO) secretory signal peptide (i.e., leader) located upstream of a multiple cloning site. Many other yeast vectors could be used in place of pPIC9K, such as, pYES2, pYDl, pTEFl/Zeo, pYES2/GS, pPICZ, pGAPZ, pGAPZalpha, pPIC9, pPIC3.5, pHIL-D2, pHIL-Sl, pPIC3.5K, and PAO815, as one skilled in the art would readily appreciate, as long as the proposed expression construct provides appropriately located signals for transcription, translation, secretion (if desired), and the like, including an in-frame AUG as required. In another embodiment, high-level expression of a heterologous coding sequence, such as, for example, a Brainiac-5 polynucleotide of the present invention, may be achieved by cloning the heterologous polynucleotide of the invention into an expression vector such as, for example, pGAPZ or pGAPZalpha, and growing the yeast culture in the absence of methanol. Transcription of the DNA encoding the polypeptides of the present invention by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are -acting elements of DNA, usually about from 10 to 300 bp that act on a promoter to increase its transcription. Examples including the SV40 enhancer on the late side of the replication origin bp 100 to 270, a cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers. Various mammalian cell culture systems can also be employed to express recombinant protein. Examples of mammalian expression systems include the COS-7 lines of monkey kidney fibroblasts, described by Gluzman (Cell 23:175 (1981)), and other cell lines capable of expressing a compatible vector, for example, the C127, 3T3, CHO, HeLa and BHK cell lines. Mammalian expression vectors will comprise an origin of replication, a suitable promoter and enhancer, and also any necessary ribosome binding sites, polyadenylation site, splice donor and acceptor sites, transcriptional termination sequences, and 5' flanking nontranscribed sequences. DNA sequences derived from the SV40 splice, and polyadenylation sites may be used to provide the required nontranscribed genetic elements. In addition to encompassing host cells containing the vector constructs discussed herein, the invention also encompasses primary, secondary, and immortalized host cells of vertebrate origin, particularly mammalian origin, that have been engineered to delete or replace endogenous genetic material (e.g., Brainiac-5 coding sequence), and/or to include genetic material (e.g., heterologous polynucleotide sequences) that is operably associated with Brainiac-5 polynucleotides of the invention, and which activates, alters, and/or amplifies endogenous Brainiac-5 polynucleotides. For example, techniques known in the art may be used to operably associate heterologous control regions (e.g., promoter and/or enhancer) and endogenous Brainiac-5 polynucleotide sequences via homologous recombination (see, e.g., U.S. Patent No. 5,641,670, issued June 24, 1997; International Publication No. WO 96/29411, published September 26, 1996; International Publication No. WO 94/12650, published August 4, 1994; Koller et al., Proc. Natl. Acad. Sci. USA 86:8932-8935 (1989); and Zijlstra et al., Nature 342:435-438 (1989), the disclosures of each of which are incoφorated by reference in their entireties). The host cells described infra can be used in a conventional manner to produce the gene product encoded by the recombinant sequence. Alternatively, cell-free translation systems can also be employed to produce the polypeptides of the invention using RNAs derived from the DNA constructs of the present invention. Introduction of the construct into the host cell can be effected by calcium phosphate transfection, DEAE-dextran mediated transfection, cationic lipid-mediated transfection, electroporation, transduction, infection or other methods. Such methods are described in many standard laboratory manuals (for example, Davis, et al, Basic Methods In Molecular Biology (1986)). The polypeptide may be expressed in a modified form, such as a fusion protein, and may include not only secretion signals, but also additional heterologous functional regions. For instance, a region of additional amino acids, particularly charged amino acids, may be added to the N-terminus of the polypeptide to improve stability and persistence in the host cell, during purification, or during subsequent handling and storage. Also, peptide moieties may be added to the polypeptide to facilitate purification. Such regions may be removed prior to final preparation of the polypeptide. The addition of peptide moieties to polypeptides to engender secretion or excretion, to improve stability and to facilitate purification, among others, are familiar and routine techniques in the art. A preferred fusion protein comprises a heterologous region from immunoglobuhn that is useful to stabilize and purify polypeptides. For example, EP-A-O 464 533 (Canadian counterpart 2045869) discloses fusion proteins comprising various portions of constant region of immunoglobuhn molecules together with another human protein or part thereof. In many cases, the Fc part in a fusion protein is thoroughly advantageous for use in therapy and diagnosis and thus results, for example, in improved pharmacokinetic properties (EP-A 0232 262). On the other hand, for some uses it would be desirable to be able to delete the Fc part after the fusion protein has been expressed, detected and purified in the advantageous manner described. This is the case when Fc portion proves to be a hindrance to use in therapy and diagnosis, for example when the fusion protein is to be used as antigen for immunizations. In drug discovery, for example, human proteins, such as hIL-5, have been fused with Fc portions for the purpose of high-throughput screening assays to identify antagonists of hIL-5 (Bennett, D., et al, J. Molecular Recognition 8:52-58 (1995); Johanson, K., et al, J. Biol Chem. 270:9459-9471 (1995)). In one embodiment, polynucleotides encoding Brainiac-5 polypeptides of the invention may be fused to the pelB pectate lyase signal sequence to increase the efficiency to expression and purification of such polypeptides in Gram-negative bacteria. See, U.S. Patent Nos. 5,576,195 and 5,846,818, the contents of which are herein incoφorated by reference in their entireties. A preferred fusion protein of the invention comprises a heterologous region from immunoglobuhn that is useful to stabilize and purify proteins. For example, EP-A-O 464 533 (Canadian counteφart 2045869) discloses fusion proteins comprising various portions of constant region of immunoglobuhn molecules together with another human protein or part thereof. In many cases, the Fc part in a fusion protein is thoroughly advantageous for use in therapy and diagnosis and thus results, for example, in improved pharmacokinetic properties (EP-A 0232 262). On the other hand, for some uses it would be desirable to be able to delete the Fc part after the fusion protein has been expressed, detected and purified in the advantageous manner described. This is the case when Fc portion proves to be a hindrance to use in therapy and diagnosis, for example when the fusion protein is to be used as antigen for immunizations. In drug discovery, for example, human proteins, such as hIL-5 has been fused with Fc portions for the puφose of high-throughput screening assays to identify antagonists of hIL-5. See, D. Bennett et al., J. Molecular Recognition 5:52-58 (1995) and K. Johanson et al, J. Biol Chem. 270:9459-9471 (1995). Polypeptides of the present invention include naturally purified products, products of chemical synthetic procedures, and products produced by recombinant techniques from a prokaryotic or eukaryotic host, including, for example, bacterial, yeast, higher plant, insect and mammalian cells. Depending upon the host employed in a recombinant production procedure, the polypeptides of the present invention may be glycosylated or may be non-glycosylated. In addition, polypeptides of the invention may also include an initial modified methionine residue, in some cases as a result of host-mediated processes. Polypeptides of the invention can be chemically synthesized using techniques known in the art (e.g., see Creighton, 1983, Proteins: Structures and Molecular Principles, W.H. Freeman & Co., N.Y., and Hunkapiller, M., et al., 1984, Nature 310: 105-111). For example, a peptide corresponding to a fragment of the complete Brainiac-5 polypeptides of the invention can be synthesized by use of a peptide synthesizer. Furthermore, if desired, nonclassical amino acids or chemical amino acid analogs can be introduced as a substitution or addition into the Brainiac-5 polynucleotide sequence. Non-classical amino acids include, but are not limited to, to the D-isomers of the common amino acids, 2,4-diaminobutyric acid, a-amino isobutyric acid, 4-aminobutyric acid, Abu, 2-amino butyric acid, g-Abu, e-Ahx, 6-amino hexanoic acid, Aib, 2-amino isobutyric acid, 3-amino propionic acid, ornithine, norleucine, norvaline, hydroxyproline, sarcosine, citrulline, homocitrulline, cysteic acid, t-butylglycine, t-butylalanine, phenylglycine, cyclohexylalanine, b- alanine, fluoro-amino acids, designer amino acids such as b-methyl amino acids, Ca- methyl amino acids, Na-methyl amino acids, and amino acid analogs in general. Furthermore, the amino acid can be D (dextrorotary) or L (levorotary). The invention encompasses Brainiac-5 polypeptides which are differentially modified during or after translation, e.g., by glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to an antibody molecule or other cellular ligand, etc. Any of numerous chemical modifications may be carried out by known techniques, including but not limited, to specific chemical cleavage by cyanogen bromide, trypsin, chymotrypsin, papain, V8 protease, NaBH 4 , acetylation, formylation, oxidation, reduction, metabolic synthesis in the presence of tunicamycin, etc. Additional post-translational modifications encompassed by the invention include, for example, e.g., N-linked or O-linked carbohydrate chains, processing of < N-terminal or C-terminal ends), attachment of chemical moieties to the amino acid backbone, chemical modifications of N-linked or O-linked carbohydrate chains, and addition or deletion of an N-terminal methionine residue as a result of procaryotic host cell expression. The polypeptides may also be modified with a detectable label, such as an enzymatic, fluorescent, isotopic or affinity label to allow for detection and isolation of the protein. In addition, polypeptides of the invention may be modified by iodination. In one embodiment, Brainiac-5 polypeptides of the invention may also be labeled with biotin. In other related embodiments, biotinylated Brainiac-5 polypeptides of the invention may be used, for example, as an imaging agent or as a means of identifying one or more Brainiac-5 receptor(s) or other coreceptor or coligand molecules. Also provided by the invention are chemically modified derivatives of Brainiac-5 which may provide additional advantages such as increased solubility, stability and circulating time of the polypeptide, or decreased immunogenicity (see U. S. Patent No. 4,179,337). The chemical moieties for derivitization may be selected from water soluble polymers such as polyethylene glycol, ethylene glycol/propylene glycol copolymers, carboxymethylcellulose, dextran, polyvinyl alcohol and the like. The polypeptides may be modified at random positions within the molecule, or at predetermined positions within the molecule and may include one, two, three or more attached chemical moieties. The polymer may be of any molecular weight, and may be branched or unbranched. For polyethylene glycol, the preferred molecular weight is between about 1 kDa and about 100 kDa (the term "about" indicating that in preparations of polyethylene glycol, some molecules will weigh more, some less, than the stated molecular weight) for ease in handling and manufacturing. Other sizes may be used, depending on the desired therapeutic profile (e.g., the duration of sustained release desired, the effects, if any on biological activity, the ease in handling, the degree or lack of antigenicity and other known effects of the polyethylene glycol to a therapeutic protein or analog). The polyethylene glycol molecules (or other chemical moieties) should be attached to the protein with consideration of effects on functional or antigenic domains of the protein. There are a number of attachment methods available to those skilled in the art, e.g., EP 0401 384, herein incoφorated by reference (coupling PEG to G-CSF), see also Malik et al., Exp. Hematol. 20:1028-1035 (1992) (reporting pegylation of GM-CSF using tresyl chloride). For example, polyethylene glycol may be covalently bound through amino acid residues via a reactive group, such as, a free amino or carboxyl group. Reactive groups are those to which an activated polyethylene glycol molecule may be bound. The amino acid residues having a free amino group may include lysine residues and the N-terminal amino acid residues; those having a free carboxyl group may include aspartic acid residues, glutamic acid residues, and the C-terminal amino acid residue. Sulfhydryl groups may also be used as a reactive group for attaching the polyethylene glycol molecules. Preferred for therapeutic puφoses is attachment at an amino group, such as attachment at the N-terminus or lysine group. One may specifically desire proteins chemically modified at the N-terminus. Using polyethylene glycol as an illustration, one may select from a variety of polyethylene glycol molecules (by molecular weight, branching, etc.), the proportion of polyethylene glycol molecules to protein (or peptide) molecules in the reaction mix, the type of pegylation reaction to be performed, and the method of obtaining the selected N-terminally pegylated protein. The method of obtaining the N-terminally pegylated preparation (i.e., separating this moiety from other monopegylated moieties if necessary) may be by purification of the N-terminally pegylated material from a population of pegylated protein molecules. Selective proteins chemically modified at the N-terminus modification may be accomplished by reductive alkylation which exploits differential reactivity of different types of primary amino groups (lysine versus the N-terminal) available for derivatization in a particular protein. Under the appropriate reaction conditions, substantially selective derivatization of the protein at the N-terminus with a carbonyl group containing polymer is achieved. The Brainiac-5 polypeptides of the invention can be recovered and purified by well-known methods including ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxylapatite chromatography and lectin chromatography. Most preferably, high performance liquid chromatography ("HPLC") is employed for purification. Polypeptides of the present invention include: products purified from natural sources, including bodily fluids, tissues and cells, whether directly isolated or cultured; products of chemical synthetic procedures; and products produced by recombinant techniques from a prokaryotic or eukaryotic host, including, for example, bacterial, yeast, higher plant, insect and mammalian cells. Depending upon the host employed in a recombinant production procedure, the polypeptides of the present invention may be glycosylated or may be non-glycosylated. In addition, polypeptides of the invention may also include an initial modified methionine residue, in some cases as a result of host-mediated processes. Thus, it is well known in the art that the N-terminal methionine encoded by the translation initiation codon generally is removed with high efficiency from any protein after translation in all eukaryotic cells. While the N-terminal methionine on most proteins also is efficiently removed in most prokaryotes, for some proteins this prokaryotic removal process is inefficient, depending on the nature of the amino acid to which the N-terminal methionine is covalently linked. Polypeptides The invention further provides an isolated Brainiac-5 polypeptide having (i.e., comprising, or alternatively consisting of) the amino acid sequence encoded by the deposited cDNA, or the amino acid sequence in SEQ ID NO:2, or a peptide or polypeptide comprising a portion of the above polypeptides. The Brainiac-5 polypeptides of the invention may be in monomers or multimers (i.e., dimers, trimers, tetramers and higher multimers). Accordingly, the present invention relates to monomers and multimers of the Brainiac-5 polypeptides of the invention, their preparation, and compositions (preferably, pharmaceutical compositions) containing them. In specific embodiments, the polypeptides of the invention are monomers, dimers, trimers or tetramers. In additional embodiments, the multimers of the invention are at least dimers, at least trimers, or at least tetramers. Multimers encompassed by the invention may be homomers or heteromers. As used herein, the term homomer, refers to a multimer containing only Brainiac-5 polypeptides of the invention (including Brainiac-5 fragments, variants, and fusion proteins, as described herein). These homomers may contain Brainiac-5 polypeptides having identical or different amino acid sequences. In a specific embodiment, a homomer of the invention is a multimer containing only Brainiac-5 polypeptides having an identical amino acid sequence. In another specific embodiment, a homomer of the invention is a multimer containing Brainiac-5 polypeptides having different amino acid sequences. In specific embodiments, the multimer of the invention is a homodimer (e.g., containing Brainiac-5 polypeptides having identical or different amino acid sequences) or a homotrimer (e.g., containing Brainiac-5 polypeptides having identical or different amino acid sequences). In a preferred embodiment, the multimer of the invention is a homotrimer. In additional embodiments, the homomeric multimer of the invention is at least a homodimer, at least a homotrimer, or at least a homotetramer. As used herein, the term heteromer refers to a multimer containing heterologous polypeptides (i.e., polypeptides of a different protein) in addition to the Brainiac-5 polypeptides of the invention. In a specific embodiment, the multimer of the invention is a heterodimer, a heterotrimer, or a heterotetramer. In additional embodiments, the heteromeric multimer of the invention is at least a heterodimer, at least a heterotrimer, or at least a heterotetramer. Multimers of the invention may be the result of hydrophobic, hydrophilic, ionic and/or covalent associations and/or may be indirectly linked, by for example, liposome formation. Thus, in one embodiment, multimers of the invention, such as, for example, homodimers or homotrimers, are formed when polypeptides of the invention contact one another in solution. In another embodiment, heteromultimers of the invention, such as, for example, heterotrimers or heterotetramers, are formed when polypeptides of the invention contact antibodies to the polypeptides of the invention (including antibodies to the heterologous polypeptide sequence in a fusion protein of the invention) in solution. In other embodiments, multimers of the invention are formed by covalent associations with and/or between the Brainiac-5 polypeptides of the invention. Such covalent associations may involve one or more amino acid residues contained in the polypeptide sequence (e.g., that recited in SEQ ID NO:2 or contained in the polypeptide encoded by the clone deposited in connection with this application). In one instance, the covalent associations are cross-linking between cysteine residues located within the polypeptide sequences which interact in the native (i.e., naturally occurring) polypeptide. In another instance, the covalent associations are the consequence of chemical or recombinant manipulation. Alternatively, such covalent associations may involve one or more amino acid residues contained in the heterologous polypeptide sequence in a Brainiac-5 fusion protein. In one example, covalent associations are between the heterologous sequence contained in a fusion protein of the invention (see, e.g., US Patent Number 5,478,925). In a specific example, the covalent associations are between the heterologous sequence contained in a Brainiac-5-Fc fusion protein of the invention (as described herein). In another specific example, covalent associations of fusion proteins of the invention are between heterologous polypeptide sequence from another protein that is capable of forming covalently associated multimers, such as for example, oseteoprotegerin (see, e.g., International Publication No. WO 98/49305, the contents of which are herein incoφorated by reference in its entirety). In another embodiment, two or more Brainiac-5 polypeptides of the invention are joined through synthetic linkers (e.g., peptide, carbohydrate or soluble polymer linkers). Examples include those peptide linkers described in U.S. Pat. No. 5,073,627 (hereby incoφorated by reference). Proteins comprising multiple Brainiac-5 polypeptides separated by peptide linkers may be produced using conventional recombinant DNA technology. Another method for preparing multimer Brainiac-5 polypeptides of the invention involves use of Brainiac-5 polypeptides fused to a leucine zipper polypeptide sequence. Leucine zipper domains are polypeptides that promote multimerization of the proteins in which they are found. Leucine zippers were originally identified in several DNA-binding proteins (Landschulz et al., Science 240:1759, (1988)), and have since been found in a variety of different proteins. Among the known leucine zippers are naturally occurring peptides and derivatives thereof that dimerize or trimerize. Examples of leucine zipper domains suitable for producing soluble multimeric Brainiac-5 proteins are those described in PCT application WO 94/10308, hereby incoφorated by reference. Recombinant fusion proteins comprising a soluble Brainiac-5 polypeptide fused to a peptide that dimerizes or trimerizes in solution are expressed in suitable host cells, and the resulting soluble multimeric Brainiac-5 is recovered from the culture supernatant using techniques known in the art. Trimeric Brainiac-5 may offer the advantage of enhanced biological activity. Preferred leucine zipper moieties are those that preferentially form trimers. One example is a leucine zipper derived from lung surfactant protein D (SPD), as described in Hoppe et al. (FEBS Letters 344:191, (1994)) and in U.S. patent application Ser. No. 08/446,922, hereby incoφorated by reference. Other peptides derived from naturally occurring trimeric proteins may be employed in preparing trimeric Brainiac-5. In another example, proteins of the invention are associated by interactions between the Flag® polypeptide sequence contained in Flag®-Brainiac-5 fusion proteins of the invention. In a further embodiment, proteins of the invention are associated by interactions between the heterologous polypeptide sequence contained in Flag®-Brainiac-5 fusion proteins of the invention and anti-Flag® antibody. The multimers of the invention may be generated using chemical techniques known in the art. For example, polypeptides desired to be contained in the multimers of the invention may be chemically cross-linked using linker molecules and linker molecule length optimization techniques known in the art (see, e.g., US Patent Number 5,478,925, which is herein incoφorated by reference in its entirety). Additionally, multimers of the invention may be generated using techniques known in the art to form one or more inter-molecule cross-links between the cysteine residues located within the sequence of the polypeptides desired to be contained in the multimer (see, e.g., US Patent Number 5,478,925, which is herein incorporated by reference in its entirety). Further, polypeptides of the invention may be routinely modified by the addition of cysteine or biotin to the C terminus or N-terminus of the polypeptide and techniques known in the art may be applied to generate multimers containing one or more of these modified polypeptides (see, e.g., US Patent Number 5,478,925, which is herein incoφorated by reference in its entirety). Additionally, techniques known in the art may be applied to generate liposomes containing the polypeptide components desired to be contained in the multimer of the invention (see, e.g., US Patent Number 5,478,925, which is herein incoφorated by reference in its entirety). Alternatively, multimers of the invention may be generated using genetic engineering techniques known in the art. In one embodiment, polypeptides contained in multimers of the invention are produced recombinantly using fusion protein technology described herein or otherwise known in the art (see, e.g., US Patent Number 5,478,925, which is herein incoφorated by reference in its entirety). In a specific embodiment, polynucleotides coding for a homodimer of the invention are generated by ligating a polynucleotide sequence encoding a polypeptide of the invention to a sequence encoding a linker polypeptide and then further to a synthetic polynucleotide encoding the translated product of the polypeptide in the reverse orientation from the original C-terminus to the N-terminus (lacking the leader sequence) (see, e.g., US Patent Number 5,478,925, which is herein incorporated by reference in its entirety). In another embodiment, recombinant techniques described herein or otherwise known in the art are applied to generate recombinant polypeptides of the invention which contain a transmembrane domain and which can be incoφorated by membrane reconstitution techniques into liposomes (see, e.g., US Patent Number 5,478,925, which is herein incorporated by reference in its entirety). In one embodiment, the invention provides an isolated Brainiac-5 polypeptide having (i.e., comprising, or alternatively consisting of) the amino acid sequence encoded by the cDNA clone contained in ATCC No. 203572, or the amino acid sequence in Figures 1A and IB (SEQ ID NO:2), or a peptide or polypeptide comprising a portion (i.e., a fragment) of the above polypeptides. Polypeptide fragments of the present invention include polypeptides comprising or alternatively, consisting of, an amino acid sequence contained in SEQ ID NO:2, encoded by the cDNA contained in the plasmid having ATCC accession number 203572, or encoded by nucleic acids which hybridize (e.g., under stringent hybridization conditions) to the nucleotide sequence contained in the deposited clone, or the complementary strand of the nucleotide sequence shown in Figures 1A-B (SEQ ID NO:l). Polypeptide fragments may be "free-standing," or comprised within a larger polypeptide of which the fragment forms a part or region, most preferably as a single continuous region. Representative examples of polypeptide fragments of the invention, include, for example, fragments that comprise or alternatively, consist of, from about amino acid residues: 1 to 15, 16-30, 31-46, 47-55, 56-72, 73-104, 105-163, 163-188, 186-210 and 210-278 of the amino acid sequence disclosed in SEQ ID NO:2. Moreover, polypeptide fragments can be at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 175 or 200 amino acids in length. In this context, "about" means several, a few, 5, 4, 3, 2 or 1. Polynucleotides encoding these polypeptide fragments are also encompassed by the invention. Additional polypeptide fragments of the invention comprise, or alternatively consist of, amino acids 7 to 20, 7 to 33, 61 to 83, 105 to 119, 139 to 148, 160 to 171, 187 to 196 of SEQ ID NO:2. Polypeptides encoded by these polynucleotides are also encompassed by the invention. Additional embodiments encompass Brainiac-5 polypeptide fragments comprising, or alternatively consisting of, one, two, three, four, five or more functional regions of polypeptides of the invention, such as the Garnier-Robson alpha-regions, beta-regions, turn-regions, and coil-regions, Chou-Fasman alpha-regions, beta-regions, and coil-regions, Kyte-Doolittle hydrophilic regions and hydrophobic regions, Eisenberg alpha- and beta-amphipathic regions, Kaφlus-Schulz flexible regions, Emini surface-forming regions and Jameson-Wolf regions of high antigenic index set out in Figures 3 and in Table I and as described herein. In a preferred embodiment, the polypeptide fragments of the invention are antigenic. The data presented in columns VIII, IX, XIII, and XIV of Table I can be used to routinely determine regions of Brainiac-5 which exhibit a high degree of potential for antigenicity. Regions of high antigenicity are determined from the data presented in columns VIII, IX, XIII, and/or IV by choosing values which represent regions of the polypeptide which are likely to be exposed on the surface of the polypeptide in an environment in which antigen recognition may occur in the process of initiation of an immune response (e.g., a polypeptide comprising amino acid residues from about Val-1 to about Val-11 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Thr- 14 to about Gln-22 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Val-34 to about His-53 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Phe-94 to about Val- 108 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Ala- 120 to about Gin- 126 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Arg- 138 to about He- 149 in SEQ ID NO:2; a polypeptide comprising amino acid residues from about Leu-202 to about Ala-211 in SEQ ID NO:2; and a polypeptide comprising amino acid residues from about Phe-274 to about Ser-278 in SEQ ID NO:2). Among highly preferred fragments of the invention are those that comprise regions of Brainiac-5 that combine several structural features, such as several (e.g., 1, 2, 3 or 4) of the features set out above. Polynucleotides encoding these polypeptides are also encompassed by the invention. In another embodiment, the invention provides a peptide or polypeptide comprising an epitope-bearing portion of a polypeptide of the invention. The epitope of this polypeptide portion is an immunogenic or antigenic epitope of a polypeptide of the invention. An "immunogenic epitope" is defined as a part of a polypeptide that elicits an antibody response when the complete or whole polypeptide is the immunogen. On the other hand, a region of a protein molecule to which an antibody can bind is defined as an "antigenic epitope." The number of immunogenic epitopes of a protein generally is less than the number of antigenic epitopes (see, for instance, Geysen, et al, Proc. Natl Acad. Sci. USA 81:3998-4002 (1983)). As to the selection of peptides or polypeptides bearing an antigenic epitope (i.e., that contain a region of a polypeptide molecule to which an antibody can bind), it is well known in that art that relatively short synthetic peptides that mimic part of a polypeptide sequence are routinely capable of eliciting an antiserum that reacts with the partially mimicked polypeptide (see, for instance, Sutcliffe, J. G., et al, Science 219:660-666 (1983)). Peptides capable of eliciting protein-reactive sera are frequently represented in the primary sequence of a polypeptide, can be characterized by a set of simple chemical rules, and are confined neither to immunodominant regions of intact polypeptides (i.e., immunogenic epitopes) nor to the amino or carboxyl terminals. Antigenic epitope-bearing peptides and polypeptides of the invention are therefore useful to raise antibodies, including monoclonal antibodies, that bind specifically to a polypeptide of the invention (see, for instance, Wilson, et al, Cell 37:767-778 (1984)). Antigenic epitope-bearing peptides and polypeptides of the invention preferably contain a sequence of at least seven, more preferably at least nine and most preferably between about 15 to about 30 amino acids contained within the amino acid sequence of a polypeptide of the invention. Non-limiting examples of antigenic polypeptides or peptides that can be used to generate Brainiac-5-specific antibodies include: a polypeptide comprising amino acid residues from about Val-1 to about Val-11 in SEQ ID NO:2; from about Thr- 14 to about Gln-22 in SEQ ID NO:2; from about Val-34 to about His-53 in SEQ ID NO:2; from about Phe-94 to about Val- 108 in SEQ ID NO:2; from about Ala- 120 to about Gln-126 in SEQ ID NO:2; from about Arg- 138 to about He- 149 in SEQ ID NO:2; ; from about Leu-202 to about Ala-211 in SEQ ID NO:2; and from about Phe-274 to about Ser-278 in SEQ ID NO:2. These polypeptide fragments have been determined to bear antigenic epitopes of the Brainiac-5 polypeptide by the analysis of the Jameson-Wolf antigenic index, as shown in Figure 3 and/or Table I, above. The epitope-bearing peptides and polypeptides of the invention may be produced by any conventional means (see, for example, Houghten, R. A., et al, Proc. Natl Acad. Sci. USA 52:5131-5135 (1985); and U.S. Patent No. 4,631,211 to Houghten, et al. (1986)). Epitope-bearing peptides and polypeptides of the invention are used to induce antibodies according to methods well known in the art (see, for instance, Sutchffe, et al, supra; Wilson, et al, supra; Chow, M., et al, Proc. Natl. Acad. Sci. USA 82:910-914; and Bittle, F. J., et al, J. Gen. Virol. 66:2347-2354 (1985)). Immunogenic epitope-bearing peptides of the invention, i.e., those parts of a protein that elicit an antibody response when the whole protein is the immunogen, are identified according to methods known in the art (see, for instance, Geysen, et al, supra). Further still, U.S. Patent No. 5,194,392, issued to Geysen, describes a general method of detecting or determining the sequence of monomers (amino acids or other compounds) which is a topological equivalent of the epitope (i.e., a "mimotope") which is complementary to a particular paratope (antigen binding site) of an antibody of interest. More generally, U.S. Patent No. 4,433,092, issued to Geysen, describes a method of detecting or determining a sequence of monomers which is a topographical equivalent of a ligand which is complementary to the ligand binding site of a particular receptor of interest. Similarly, U.S. Patent No. 5,480,971, issued to Houghten and colleagues, on Peralkylated Oligopeptide Mixtures discloses linear Cl-C7-alkyl peralkylated oligopeptides and sets and libraries of such peptides, as well as methods for using such oligopeptide sets and libraries for determining the sequence of a peralkylated oligopeptide that preferentially binds to an acceptor molecule of interest. Thus, non-peptide analogs of the epitope-bearing peptides of the invention also can be made routinely by these methods. Brainiac-5 polypeptide-specific antibodies for use in the present invention can be raised against the intact Brainiac-5 polypeptide or an antigenic polypeptide fragment thereof, which may be presented together with a carrier protein, such as an albumin, to an animal system (such as rabbit or mouse) or, if it is long enough (at least about 25 amino acids), without a carrier. As used herein, the term "antibody" (Ab) or "monoclonal antibody" (Mab) is meant to include intact molecules as well as antibody fragments (such as, for example, Fab and F(ab')2 fragments) which are capable of specifically binding to Brainiac-5 polypeptides. Fab and F(ab')2 fragments lack the Fc fragment of intact antibody, clear more rapidly from the circulation, and may have less non-specific tissue binding of an intact antibody (Wahl, et al, J. Nucl. Med. 24:316-325 (1983)). Thus, these fragments are preferred. The antibodies of the present invention may be prepared by any of a variety of methods. For example, cells expressing the Brainiac-5 polypeptides or an antigenic fragment thereof can be administered to an animal in order to induce the production of sera containing polyclonal antibodies. In a preferred method, a preparation of Brainiac-5 polypeptide is prepared and purified to render it substantially free of natural contaminants. Such a preparation is then introduced into an animal in order to produce polyclonal antisera of greater specific activity. In the most preferred method, the antibodies of the present invention are monoclonal antibodies (or Brainiac-5 polypeptide-binding fragments thereof). Such monoclonal antibodies can be prepared using hybridoma technology (Kohler, et al, Nature 256:495 (1975); Kohler, et al, Eur. J. Immunol. 6:511 (1976); Kohler, et al, Eur. J. Immunol. 6:292 (1976); Hammerling, et al, in: Monoclonal Antibodies and T-Cell Hybridomas, Elsevier, N.Y., (1981) pp. 563-681)). In general, such procedures involve immunizing an animal (preferably a mouse) with a Brainiac-5 polypeptide antigen or, more preferably, with a Brainiac-5 polypeptide-expressing cell. Suitable cells can be recognized by their capacity to bind anti-Brainiac-5 polypeptide antibody. Such cells may be cultured in any suitable tissue culture medium; however, it is preferable to culture cells in Earle's modified Eagle's medium supplemented with 10% fetal bovine serum (inactivated at about 56° C), and supplemented with about 10 μg/1 of nonessential amino acids, about 1,000 U/ml of penicillin, and about 100 μg/ml of streptomycin. The splenocytes of such mice are extracted and fused with a suitable myeloma cell line. Any suitable myeloma cell line may be employed in accordance with the present invention; however, it is preferable to employ the parent myeloma cell line (SP2O), available from the American Type Culture Collection, Manassas, Virginia. After fusion, the resulting hybridoma cells are selectively maintained in HAT medium, and then cloned by limiting dilution as described by Wands and colleagues (Gastroenterology 80:225-232 (1981)). The hybridoma cells obtained through such a selection are then assayed to identify clones which secrete antibodies capable of binding the Brainiac-5 polypeptide antigen. Alternatively, additional antibodies capable of binding to the Brainiac-5 polypeptide antigen may be produced in a two-step procedure through the use of anti-idiotypic antibodies. Such a method makes use of the fact that antibodies are themselves antigens, and that, therefore, it is possible to obtain an antibody which binds to a second antibody. In accordance with this method, Brainiac-5 polypeptide-specific antibodies are used to immunize an animal, preferably a mouse. The splenocytes of such an animal are then used to produce hybridoma cells, and the hybridoma cells are screened to identify clones which produce an antibody whose ability to bind to the Brainiac-5 polypeptide-specific antibody can be blocked by the Brainiac-5 polypeptide antigen. Such antibodies comprise anti-idiotypic antibodies to the Brainiac-5 polypeptide-specific antibody and can be used to immunize an animal to induce formation of further Brainiac-5 polypeptide-specific antibodies. It will be appreciated that Fab and F(ab')2 and other fragments of the antibodies of the present invention may be used according to the methods disclosed herein. Such fragments are typically produced by proteolytic cleavage, using enzymes such as papain (to produce Fab fragments) or pepsin (to produce F(ab')2 fragments). Alternatively, Brainiac-5 polypeptide-binding fragments can be produced through the application of recombinant DNA technology or through synthetic chemistry. For in vivo use of anti-Brainiac-5 in humans, it may be preferable to use "humanized" chimeric monoclonal antibodies. Such antibodies can be produced using genetic constructs derived from hybridoma cells producing the monoclonal antibodies described above. Methods for producing chimeric antibodies are known in the art (Morrison, Science 229:1202 (1985); Oi, et al, BioTechniques 4:214 (1986); Cabilly, et al, U.S. Patent No. 4,816,567; Taniguchi, et al, EP 171496; Morrison, et al, EP 173494; Neuberger, et al, WO 8601533; Robinson, et al, WO 8702671; Boulianne, et al, Nature 312:643 (1984); Neuberger, et al, Nature 314:268 (1985). The present invention encompasses polypeptides comprising, or alternatively consisting of, an epitope of the polypeptide having an amino acid sequence of SEQ ID NO:2, or an epitope of the polypeptide sequence encoded by a polynucleotide sequence contained in deposited clone 203572 or encoded by a polynucleotide that hybridizes to the complement of the sequence of SEQ ID NO: 1 or contained in deposited clone HOGCC45 under stringent hybridization conditions or lower stringency hybridization conditions as defined supra. The present invention further encompasses polynucleotide sequences encoding an epitope of a polypeptide sequence of the invention (such as, for example, the sequence disclosed in SEQ ID NO:l), polynucleotide sequences of the complementary strand of a polynucleotide sequence encoding an epitope of the invention, and polynucleotide sequences which hybridize to the complementary strand under stringent hybridization conditions or lower stringency hybridization conditions defined supra. The term "epitopes," as used herein, refers to portions of a polypeptide having antigenic or immunogenic activity in an animal, preferably a mammal, and most preferably in a human. In a preferred embodiment, the present invention encompasses a polypeptide comprising an epitope, as well as the polynucleotide encoding this polypeptide. An "immunogenic epitope," as used herein, is defined as a portion of a protein that elicits an antibody response in an animal, as determined by any method known in the art, for example, by the methods for generating antibodies described infra. (See, for example, Geysen et al., Proc. Natl. Acad. Sci. USA 81:3998-4002 (1983)). The term "antigenic epitope," as used herein, is defined as a portion of a protein to which an antibody can immunospecifically bind its antigen as determined by any method well known in the art, for example, by the immunoassays described herein. Immunospecific binding excludes non-specific binding but does not necessarily exclude cross-reactivity with other antigens. Antigenic epitopes need not necessarily be immunogenic. Fragments that function as epitopes may be produced by any conventional means. (See, e.g., Houghten, Proc. Natl. Acad. Sci. USA 82:5131-5135 (1985), further described in U.S. Patent No. 4,631,211). In the present invention, antigenic epitopes preferably contain a sequence of at least 4, at least 5, at least 6, at least 7, more preferably at least 8, at least 9, at least 10, at least 15, at least 20, at least 25, and, most preferably, between about 15 to about 30 amino acids. Preferred polypeptides comprising immunogenic or antigenic epitopes are at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 amino acid residues in length. Antigenic epitopes are useful, for example, to raise antibodies, including monoclonal antibodies, that specifically bind the epitope. Antigenic epitopes can be used as the target molecules in immunoassays. (See, for instance, Wilson et al., Cell 37:767-778 (1984); Sutchffe et al., Science 219:660-666 (1983)). Similarly, immunogenic epitopes can be used, for example, to induce antibodies according to methods well known in the art. (See, for instance, Sutchffe et al., supra; Wilson et al., supra; Chow et al., Proc. Natl. Acad. Sci. USA 82:910-914; and Bittle et al., J. Gen. Virol. 66:2347-2354 (1985). A preferred immunogenic epitope includes the secreted protein. The polypeptides comprising one or more immunogenic epitopes may be presented for eliciting an antibody response together with a carrier protein, such as an albumin, to an animal system (such as, for example, rabbit or mouse), or, if the polypeptide is of sufficient length (at least about 25 amino acids), the polypeptide may be presented without a carrier. However, immunogenic epitopes comprising as few as 8 to 10 amino acids have been shown to be sufficient to raise antibodies capable of binding to, at the very least, linear epitopes in a denatured polypeptide (e.g., in Western blotting). Epitope-bearing polypeptides of the present invention may be used to induce antibodies according to methods well known in the art including, but not limited to, in vivo immunization, in vitro immunization, and phage display methods. See, e.g., Sutchffe et al., supra; Wilson et al., supra, and Bittle et al., J. Gen. Virol., 66:2347- 2354 (1985). If in vivo immunization is used, animals may be immunized with free peptide; however, anti-peptide antibody titer may be boosted by coupling the peptide to a macromolecular carrier, such as keyhole limpet hemacyanin (KLH) or tetanus toxoid. For instance, peptides containing cysteine residues may be coupled to a carrier using a linker such as maleimidobenzoyl-N-hydroxysuccinimide ester (MBS), while other peptides may be coupled to carriers using a more general linking agent such as glutaraldehyde. Animals such as, for example, rabbits, rats, and mice are immunized with either free or carrier-coupled peptides, for instance, by intraperitoneal and/or intradermal injection of emulsions containing about 100 micrograms of peptide or carrier protein and Freund's adjuvant or any other adjuvant known for stimulating an immune response. Several booster injections may be needed, for instance, at intervals of about two weeks, to provide a useful titer of anti-peptide antibody that can be detected, for example, by ELISA assay using free peptide adsorbed to a solid surface. The titer of anti-peptide antibodies in serum from an immunized animal may be increased by selection of anti-peptide antibodies, for instance, by adsoφtion to the peptide on a solid support and elution of the selected antibodies according to methods well known in the art. As one of skill in the art will appreciate, and as discussed above, the polypeptides of the present invention comprising an immunogenic or antigenic epitope can be fused to other polypeptide sequences. For example, the polypeptides of the present invention may be fused with the constant domain of immunoglobulins (IgA, IgE, IgG, IgM), or portions thereof (CHI, CH2, CH3, or any combination thereof and portions thereof) resulting in chimeric polypeptides. Such fusion proteins may facilitate purification and may increase half-life in vivo. This has been shown for chimeric proteins consisting of the first two domains of the human CD4-polypeptide and various domains of the constant regions of the heavy or light chains of mammalian immunoglobulins. See, e.g., EP 394,827; Traunecker et al., Nature, 331:84-86 (1988). IgG Fusion proteins that have a disulfide-linked dimeric structure due to the IgG portion desulfide bonds have also been found to be more efficient in binding and neutralizing other molecules than monomeric polypeptides or fragments thereof alone. See, e.g., Fountoulakis et al., J. Biochem., 270:3958-3964 (1995). Nucleic acids encoding the above epitopes can also be recombined with a gene of interest as an epitope tag (e.g., the hemagglutinin ("HA") tag or flag tag) to aid in detection and purification of the expressed polypeptide. For example, a system described by Janknecht et al. allows for the ready purification of non-denatured fusion proteins expressed in human cell lines (Janknecht et al., 1991, Proc. Natl. Acad. Sci. USA 88:8972- 897). In this system, the gene of interest is subcloned into a vaccinia recombination plasmid such that the open reading frame of the gene is translationally fused to an amino-terminal tag consisting of six histidine residues. The tag serves as a matrix-binding domain for the fusion protein. Extracts from cells infected with the recombinant vaccinia virus are loaded onto Ni 2+ nitriloacetic acid-agarose column and histidine-tagged proteins can be selectively eluted with imidazole-containing buffers. Additional fusion proteins of the invention may be generated through the techniques of gene-shuffling, motif-shuffling, exon-shuffling, and/or codon-shuffling (collectively referred to as "DNA shuffling"). DNA shuffling may be employed to modulate the activities of polypeptides of the invention, such methods can be used to generate polypeptides with altered activity, as well as agonists and antagonists of the polypeptides. See, generally, U.S. Patent Nos. 5,605,793; 5,811,238; 5,830,721; 5,834,252; and 5,837,458, and Patten et al., Curr. Opinion Biotechnol. 8:724-33 (1997); Harayama, Trends Biotechnol. 16(2):76-82 (1998); Hansson, et al., J. Mol. Biol. 287:265-76 (1999); and Lorenzo and Blasco, Biotechniques 24(2):308- 13 (1998) (each of these patents and publications are hereby incoφorated by reference in its entirety). In one embodiment, alteration of polynucleotides corresponding to SEQ ID NO: 1 and the polypeptides encoded by these polynucleotides may be achieved by DNA shuffling. DNA shuffling involves the assembly of two or more DNA segments by homologous or site-specific recombination to generate variation in the polynucleotide sequence. In another embodiment, polynucleotides of the invention, or the encoded polypeptides, may be altered by being subjected to random mutagenesis by error-prone PCR, random nucleotide insertion or other methods prior to recombination. In another embodiment, one or more components, motifs, sections, parts, domains, fragments, etc., of a polynucleotide coding a polypeptide of the invention may be recombined with one or more components, motifs, sections, parts, domains, fragments, etc. of one or more heterologous molecules. In another embodiment, the invention provides a peptide or polypeptide comprising, or alternatively consisting of, an epitope-bearing portion of a polypeptide of the invention. Polynucleotides encoding these peptides or polypeptides are also encompassed by the invention. The epitope of this polypeptide portion is an immunogenic or antigenic epitope of a polypeptide of the invention. An "immunogenic epitope" is defined as a part of a protein that elicits an antibody response when the whole protein is the immunogen. On the other hand, a region of a protein molecule to which an antibody can bind is defined as an "antigenic epitope." The number of immunogenic epitopes of a protein generally is less than the number of antigenic epitopes. See, for instance, Geysen et al, Proc. Natl. Acad. Sci. USA 57:3998- 4002 (1983). As to the selection of peptides or polypeptides bearing an antigenic epitope (i.e., that contain a region of a protein molecule to which an antibody can bind), it is well known in that art that relatively short synthetic peptides that mimic part of a protein sequence are routinely capable of eliciting an antiserum that reacts with the partially mimicked protein. See, for instance, Sutchffe, J. G., Shinnick, T. M., Green, N. and Learner, R. A. (1983) "Antibodies that react with predetermined sites on < proteins", Science, 219:660-666. Peptides capable of eliciting protein-reactive sera are frequently represented in the primary sequence of a protein, can be characterized by a set of simple chemical rules, and are confined neither to immunodominant regions of intact proteins (i.e., immunogenic epitopes) nor to the amino or carboxyl terminals. Antigenic epitope-bearing peptides and polypeptides of the invention are therefore useful to raise antibodies, including monoclonal antibodies, that bind specifically to a polypeptide of the invention. See, for instance, Wilson et al, Cell 37:1 1 -lie) (1984) at 777. Antigenic epitope-bearing peptides and polypeptides of the invention preferably contain a sequence of at least six, at least seven, at least eight, more preferably at least nine, at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 75, and most preferably between about 15 to about 30 amino acids contained within the amino acid sequence of a polypeptide of the invention. Non-limiting examples of antigenic polypeptides or peptides that can be used to generate Brainiac-5-specific antibodies include: a polypeptide comprising, or alternatively consisting of, amino acid residues from about Val-1 to about Val-11 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Thr-14 to about Gln-22 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Val-34 to about His-53 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Phe-94 to about Val-108 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Ala-120 to about Gln-126 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Arg- 138 to about He- 149 in SEQ ID NO:2; a polypeptide comprising, or alternatively consisting of, amino acid residues from about Leu-202 to about Ala-211 in SEQ ID NO:2; and a polypeptide comprising, or alternatively consisting of, amino acid residues from about Phe-274 to about Ser-278 in SEQ ID NO:2). These polypeptide fragments have been determined to bear antigenic epitopes of the Brainiac-5 polypeptide by the analysis of the Jameson-Wolf antigenic index, as shown in Figure 3 and Table I, above. Polynucleotides encoding these polypeptides are also encompassed by the invention. By "about" is meant, the particularly recited ranges and ranges larger or smaller at the N- and/or C-terminus by several, a few, 5, 4, 3, 2 or 1 residue. The epitope-bearing peptides and polypeptides of the invention may be produced by any conventional means. See, e.g., Houghten, R. A. (1985) General method for the rapid solid-phase synthesis of large numbers of peptides: specificity of antigen-antibody interaction at the level of individual amino acids. Proc. Natl. Acad. Sci. USA 52:5131-5135; this "Simultaneous Multiple Peptide Synthesis (SMPS)" process is further described in U. S. Patent No. 4,631,211 to Houghten et al. (1986). Epitope-bearing peptides and polypeptides of the invention are used to induce antibodies according to methods well known in the art. See, for instance, Sutchffe et al., supra; Wilson et al., supra; Chow, M. et al., Proc. Natl. Acad. Sci. USA 82:910-914; and Bittle, F. J. et al, J. Gen. Virol 66:2347-2354 (1985). Immunogenic epitope-bearing peptides of the invention, i.e., those parts of a protein that elicit an antibody response when the whole protein is the immunogen, are identified according to methods known in the art. See, for instance, Geysen et al., supra. Further still, U.S. Patent No. 5,194,392 to Geysen (1990) describes a general method of detecting or determining the sequence of monomers (amino acids or other compounds) which is a topological equivalent of the epitope (i.e., a "mimotope") which is complementary to a particular paratope (antigen binding site) of an antibody of interest. More generally, U.S. Patent No. 4,433,092 to Geysen (1989) describes a method of detecting or determining a sequence of monomers which is a topographical equivalent of a ligand which is complementary to the ligand binding site of a particular receptor of interest. Similarly, U.S. Patent No. 5,480,971 to Houghten, R. A. et al. (1996) on Peralkylated Oligopeptide Mixtures discloses linear Cl-C7-alkyl peralkylated oligopeptides and sets and libraries of such peptides, as well as methods for using such oligopeptide sets and libraries for determining the sequence of a peralkylated oligopeptide that preferentially binds to an acceptor molecule of interest. Thus, non-peptide analogs of the epitope-bearing peptides of the invention also can be made routinely by these methods. As one of skill in the art will appreciate, Brainiac-5 polypeptides of the present invention and the epitope-bearing fragments thereof described above can be combined with heterologous polypeptide sequences. For example, the polypeptides of the present invention may be fused with the constant domain of immunoglobulins (IgA, IgE, IgG, IgM) or portions thereof (CHI, CH2, CH3, and any combination thereof, including both entire domains and portions thereof), resulting in chimeric polypeptides. These fusion proteins facilitate purification and show an increased half-life in vivo. This has been shown, e.g., for chimeric proteins consisting of the first two domains of the human CD4-polypeptide and various domains of the constant regions of the heavy or light chains of mammalian immunoglobulins (EP A 394,827; Traunecker et al, Nature 331:84-86 (1988)). Fusion proteins that have a disulfide-linked dimeric structure due to the IgG part can also be more efficient in binding and neutralizing other molecules than the monomeric Brainiac-5 polypeptides or polypeptide fragments alone (Fountoulakis et al, J. Biochem. 270:3958-3964 (1995)). As one of skill in the art will appreciate, Brainiac-5 polypeptides of the present invention and the epitope-bearing fragments thereof described above can be combined with parts of the constant domain of immunoglobulins (IgG), resulting in chimeric polypeptides. These fusion proteins facilitate purification and show an increased half-life in vivo. This has been shown, e.g., for chimeric proteins consisting of the first two domains of the human CD4-polypeptide and various domains of the constant regions of the heavy or light chains of mammalian immunoglobulins (EP A 394,827; Traunecker, et al, Nature 331:84-86 (1988)). Fusion proteins that have a disulfide-linked dimeric structure due to the IgG part can also be more efficient in binding and neutralizing other molecules than the monomeric Brainiac-5 polypeptide or polypeptide fragment alone (Fountoulakis, et al, J. Biochem. 270:3958-3964 (1995)). In another embodiment, the Brainiac-5 polypeptides of the present invention and the epitope-bearing fragments thereof are fused with a heterologous antigen (e.g., polypeptide, carbohydrate, phospholipid, or nucleic acid). In specific embodiments, the heterologous antigen is an immunogen. The techniques of gene-shuffling, motif-shuffling, exon-shuffling, and/or codon-shuffling (collectively refeπed to as "DNA shuffling") may be employed to modulate the activities of Brainiac-5 thereby effectively generating agonists and antagonists of Brainiac-5. See generally, U.S. Patent Nos. 5,605,793, 5,811,238, 5,830,721, 5,834,252, and 5,837,458, and Patten, P. A., et al, Curr. Opinion Biotechnol. 8:724-33 (1997); Harayama, S. Trends Biotechnol. 16(2):76-82 (1998); Hansson, L. O., et al, J. Mol. Biol. 287:265-76 (1999); and Lorenzo, M. M. and Blasco, R. Biotechniques 24(2):308-13 (1998) (each of these patents and publications are hereby incoφorated by reference). In one embodiment, alteration of Brainiac-5 polynucleotides and corresponding polypeptides may be achieved by DNA shuffling. DNA shuffling involves the assembly of two or more DNA segments into a desired Brainiac-5 molecule by homologous, or site-specific, recombination. In another embodiment, Brainiac-5 polynucleotides and corresponding polypeptides may be altered by being subjected to random mutagenesis by error-prone PCR, random nucleotide insertion or other methods prior to recombination. In another embodiment, one or more components, motifs, sections, parts, domains, fragments, etc., of Brainiac- 5 may be recombined with one or more components, motifs, sections, parts, domains, fragments, etc. of one or more heterologous molecules. In preferred embodiments, the heterologous molecules are, for example, TNF-alpha, lymphotoxin-alpha (LT-alpha, also known as TNF-beta), LT-beta (found in complex heterotrimer LT-alpha2-beta), OPGL, FasL, CD27L, CD30L, CD40L, 4-1BBL, DcR3, OX40L, TNF-gamma (International Publication No. WO 96/14328), AIM-I (International Publication No. WO 97/33899), AIM-II (International Publication No. WO 97/34911), APRIL (J. Exp. Med. 188(6):1185-1190), endokine-alpha (International Publication No. WO 98/07880), OPG, OX40, and nerve growth factor (NGF), and soluble forms of Fas, CD30, CD27, CD40 and 4-IBB, TR2 (International Publication No. WO 96/34095), DR3 (International Publication No. WO 97/33904), DR4 (International Publication No. WO 98/32856), TR5 (International Publication No. WO 98/30693), TR6 (International Publication No. WO 98/30694),TR7 (International Publication No. WO 98/41629), TRANK, TR9 (International Publication No. WO 98/56892),TR10 (International Publication No. WO 98/54202),312C2 (International Publication No. WO 98/06842), TR12, CAD, and v-FLIP. In further prefeπed embodiments, the heterologous molecules are any member of the TNF family. To improve or alter the characteristics of Brainiac-5 polypeptides, protein engineering may be employed. Recombinant DNA technology known to those skilled in the art can be used to create novel mutant polypeptides or muteins including single or multiple amino acid substitutions, deletions, additions or fusion polypeptides. Such modified polypeptides can show, e.g., enhanced activity or increased stability. In addition, they may be purified in higher yields and show better solubility than the corresponding natural polypeptide, at least under certain purification and storage conditions. For instance, for many proteins, including the extracellular domain of a membrane associated protein or the mature form(s) of a secreted protein, it is known in the art that one or more amino acids may be deleted from the N-terminus or C- terminus without substantial loss of biological function. For instance, Ron and colleagues (J. Biol. Chem., 268:2984-2988 (1993)) reported modified KGF proteins that had heparin binding activity even if 3, 8, or 27 N-terminal amino acid residues were missing. In the present case, since the Brainiac-5 polypeptide of the invention is a member of the Brainiac polypeptide family, deletions of N-terminal amino acids up to the arginine at position 8 of SEQ ID NO:2 may retain some biological activity such as the ability to modulate cell growth and differentiation. Polypeptides having further N- terminal deletions including the arginine-8 residue in SEQ ID NO: 2 may not retain such biological activities, or may exhibit an alterred biological activity, because it is known that this residue in a Brainiac -related polypeptide is in the beginning of the conserved domain believed to be required for biological activities. However, even if deletion of one or more amino acids from the N-terminus of a protein results in modification or loss of one or more biological functions of the protein, other biological activities may still be retained. Thus, the ability of the shortened polypeptide to induce and/or bind to antibodies which recognize the complete or mature form of the polypeptide generally will be retained when less than the majority of the residues of the complete or mature form of the polypeptide are removed from the N-terminus. Whether a particular polypeptide lacking N-terminal residues of a complete polypeptide retains such immunologic activities can readily be determined by routine methods described herein and otherwise known in the art. Accordingly, the present invention further provides polypeptides having one or more residues deleted from the amino terminus of the amino acid sequence of the Brainiac-5 polypeptide shown in SEQ ID NO:2, up to the arginine residue at position number 8, and polynucleotides encoding such polypeptides. In particular, the present invention provides polypeptides comprising, or alternatively consisting of, the amino acid sequence of residues n'-278 of SEQ ID NO:2, where n 1 is an integer in the range of 1 to 8, and 9 is the position of the first residue from the N-terminus of the complete Brainiac-5 polypeptide (shown in SEQ ID NO:2) believed to be required for modulation of cell growth and differentiation activity of the Brainiac-5 polypeptide. More in particular, the invention provides nucleic acid molecules encoding polypeptides having (i.e., comprising, or alternatively consisting of) the amino acid sequence of residues of 1-278; 2-278; 3-278; 4-278; 5-278; 6-278; 7-278; or 8-278 of SEQ ID NO:2. The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above nucleic acid molecule sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molecules are also provided. Similarly, many examples of biologically functional C-terminal deletion muteins are known. For instance, Interferon gamma shows up to ten times higher activities by deleting 8-10 amino acid residues from the carboxy terminus of the protein (Dobeli, et al, J. Biotechnology 7: 199-216 (1988)). In the present case, since the Brainiac-5 polypeptide of the invention is a member of the Brainiac polypeptide family, deletions of C-terminal amino acids up to the cysteine at position 263 of SEQ ID NO:2 may retain some biological activity such as the ability to modulate cell growth and differentiation. Polypeptides having further C-terminal deletions including the cysteine residue at position 263 of SEQ ID NO: 2 may not retain such biological activities because this residue is in the beginning of the conserved domain required for biological activities. However, even if deletion of one or more amino acids from the C-terminus of a protein results in modification of loss of one or more biological functions of the protein, other biological activities may still be retained. Thus, the ability of the shortened protein to induce and/or bind to antibodies which recognize the complete or mature form of the polypeptide generally will be retained when less than the majority of the residues of the complete or mature form of the polypeptide are removed from the C-terminus. Whether a particular polypeptide lacking C-terminal residues of a complete protein retains such immunologic activities can readily be determined by routine methods described herein and otherwise known in the art. Accordingly, the present invention further provides polypeptides having one or more residues from the carboxy terminus of the amino acid sequence of the Brainiac-5 polypeptide shown in SEQ ID NO:2, up to the cysteine residue at position 263 of SEQ ID NO:2, and polynucleotides encoding such polypeptides. In particular, the present invention provides polypeptides having (i.e., comprising, or alternatively consisting of) the amino acid sequence of residues 1-m 1 of the amino acid sequence in SEQ ID NO:2, where m 1 is any integer in the range of 263 to 278, and residue 262 is the position of the first residue from the C- terminus of the complete Brainiac-5 polypeptide (shown in SEQ ID NO:2) believed to be required for the cell growth and differentiation modulatory activities of the Brainiac-5 polypeptide. More in particular, the invention provides nucleic acid molecules encoding polypeptides having (i.e., comprising, or alternatively consisting of) the amino acid sequence of residues 1-278; 1-277; 1-276; 1-275; 1-274; 1-273; 1-272; 1-271; 1-270; 1-269; 1-268; 1-267; 1-266; 1-265; 1-264; or 1-263 of SEQ ID NO:2. The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above polynucleotide sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molecules are also are provided. The invention also provides nucleic acid molecules encoding polypeptides having (i.e., comprising, or alternatively consisting of) one or more amino acids deleted from both the amino and the carboxyl termini, which may be described generally as having residues n'-m 1 of SEQ ID NO:2, where n 1 and m 1 are integers as described above e.g., a polypeptide comprising, or alternatively consisting of, amino acids 8 to 263 of SEQ ID NO:2). The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above polynucleotide sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molecules are also encompassed by the invention. Also included are a nucleotide sequence encoding a polypeptide consisting of a portion of the complete Brainiac-5 amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572, where this portion excludes any integer from 1 to about 7 amino acids from the amino terminus of the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572, or any integer from 1 to about 15 amino acids from the carboxy terminus, or any combination of the above amino terminal and carboxy terminal deletions, of the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572. In this context, "about" means the recited value and values that are larger or smaller by several, a few, a small number, 5, 4, 3, 2 or 1. As mentioned above, even if deletion of one or more amino acids from the N-terminus of a protein results in modification of loss of one or more functional activities of the protein (e.g., activation of the Notch signaling pathway, mediation of protein-protein interactions (e.g., between Brainiac-5 and Su(H) or a human homolog of Su(H)), and/or binding of an antibody specific to Brainiac-5), other functional and or biological activities may still be retained. Thus, the ability of shortened Brainiac-5 muteins to induce and/or bind to antibodies which recognize the complete or mature forms of the polypeptides generally will be retained when less than the majority of the residues of the complete or mature polypeptide are removed from the N-terminus. Whether a particular polypeptide lacking N-terminal residues of a complete polypeptide retains such immunologic activities can readily be determined by routine methods described herein and otherwise known in the art. It is not unlikely that a Brainiac-5 mutein with a large number of deleted N-terminal amino acid residues may retain some biological or immunogenic activities. In fact, peptides composed of as few as six Brainiac-5 amino acid residues may often evoke an immune response. Accordingly, the present invention further provides polypeptides having one or more residues deleted from the amino terminus of the Brainiac-5 amino acid sequence shown in Figures 1A and IB (i.e., SEQ ID NO:2), up to the proline residue at position number 273 and polynucleotides encoding such polypeptides. In particular, the present invention provides polypeptides comprising the amino acid sequence of residues n 2 -278 of Figures 1A and IB (SEQ ID NO:2), where n 2 is an integer in the range of 2 to 273, and 273 is the position of the first residue from the N-terminus of the complete Brainiac-5 polypeptide believed to be required for at least immunogenic activity of the Brainiac-5 polypeptide. More in particular, the invention provides nucleic acid molecules encoding polypeptides comprising, or alternatively consisting of, the amino acid sequence of residues of A-2 to S-278; E-3 to S-278; D-4 to S-278; F-5 to S-278; E-6 to S-278; R-7 to S-278; R-8 to S-278; Q-9 to S-278; A-10 to S-278; V-l 1 to S-278; R-12 to S-278; Q-13 to S-278; T-14 to S-278; W-15 to S-278; G-16 to S-278; A-17 to S-278; E-18 to S-278; G-19 to S-278; R-20 to S-278; V-21 to S-278; Q-22 to S-278; G-23 to S-278; A-24 to S-278; L-25 to S-278; V-26 to S-278; R-27 to S-278; R-28 to S-278; V-29 to S-278; F-30 to S-278; L-31 to S-278; L-32 to S-278; G-33 to S-278; V-34 to S-278; P-35 to S-278; R-36 to S-278; G-37 to S-278; A-38 to S-278; G-39 to S-278; S-40 to S-278; G-41 to S-278; G-42 to S-278; A-43 to S-278; D-44 to S-278; E-45 to S-278; V-46 to S-278; G-47 to S-278; E-48 to S-278; G-49 to S-278; A-50 to S-278; R-51 to S-278; T-52 to S-278; H-53 to S-278; W-54 to S-278; R-55 to S-278; A-56 to S-278; L-57 to S-278; L-58 to S-278; R-59 to S-278; A-60 to S-278; E-61 to S-278; S-62 to S-278; L-63 to S-278; A-64 to S-278; Y-65 to S-278; A-66 to S-278; D-67 to S-278; 1-68 to S-278; L-69 to S-278; L-70 to S-278; W-71 to S-278; A-72 to S-278; F-73 to S-278; D-74 to S-278; D-75 to S-278; T-76 to S-278; F-77 to S-278; F-78 to S-278; N-79 to S-278; L-80 to S-278; T-81 to S-278; L-82 to S-278; K-83 to S-278; E-84 to S-278; 1-85 to S-278; H-86 to S-278; F-87 to S-278; L-88 to S-278; A-89 to S-278; W-90 to S-278; A-91 to S-278; S-92 to S-278; A-93 to S-278; F-94 to S-278; C-95 to S-278; P-96 to S-278; D-97 to S-278; V-98 to S-278; R-99 to S-278; F-100 to S-278; V-101 to S-278; F-102 to S-278; K-103 to S-278; G-104 to S-278; D-105 to S-278; A-106 to S-278; D-107 to S-278; V-108 to S-278; F-109 to S-278; V-l 10 to S-278; N-111 to S-278; V-l 12 to S-278; G-l 13 to S-278; N-114 to S-278; L-l 15 to S-278; L-l 16 to S-278; E-l 17 to S-278; F-l 18 to S-278; L-l 19 to S-278; A-120 to S-278; P-121 to S-278 R-122 to S-278; D-123 to S-278; P-124 to S-278; A-125 to S-278; Q-126 to S-278 D-127 to S-278; L-128 to S-278; L-129 to S-278; A-130 to S-278; G-131 to S-278 D-132 to S-278; V-133 to S-278; 1-134 to S-278; V-135 to S-278; H-136 to S-278 A-137 to S-278; R-138 to S-278; P-139 to S-278; 1-140 to S-278; R-141 to S-278 T-142 to S-278; R-143 to S-278; A-144 to S-278; S-145 to S-278; K-146 to S-278 Y-147 to S-278; Y-148 to S-278; 1-149 to S-278; P-150 to S-278; E-151 to S-278 A-152 to S-278; V-153 to S-278; Y-154 to S-278; G-155 to S-278; L-l 56 to S-278 P-157 to S-278; A-158 to S-278; Y-159 to S-278; P-160 to S-278; A- 161 to S-278 Y-162 to S-278; A-163 to S-278; G-164 to S-278; G-165 to S-278; G-166 to S-278 G-167 to S-278; F-168 to S-278; V-l 69 to S-278; L-l 70 to S-278; S-171 to S-278 G-172 to S-278; A- 173 to S-278; T-174 to S-278; L-l 75 to S-278; H-176 to S-278 R-177 to S-278; L-178 to S-278; A-179 to S-278; G-180 to S-278; A-181 to S-278 C-182 to S-278; A-183 to S-278; Q-184 to S-278; V-185 to S-278; E-186 to S-278 L-187 to S-278; F-188 to S-278; P-189 to S-278; 1-190 to S-278; D-191 to S-278 D-192 to S-278; V-193 to S-278; F-194 to S-278; L-195 to S-278; G-196 to S-278 M-197 to S-278; C-198 to S-278; L-199 to S-278; Q-200 to S-278; R-201 to S-278 L-202 to S-278; R-203 to S-278; L-204 to S-278; T-205 to S-278; P-206 to S-278 E-207 to S-278; P-208 to S-278; H-209 to S-278; P-210 to S-278; A-211 to S-278 F-212 to S-278; R-213 to S-278; T-214 to S-278; F-215 to S-278; G-216 to S-278 1-217 to S-278; P-218 to S-278; Q-219 to S-278; P-220 to S-278; S-221 to S-278 A-222 to S-278; A-223 to S-278; P-224 to S-278; H-225 to S-278; L-226 to S-278 S-227 to S-278; T-228 to S-278; F-229 to S-278; D-230 to S-278; P-231 to S-278 C-232 to S-278; F-233 to S-278; Y-234 to S-278; R-235 to S-278; E-236 to S-278 L-237 to S-278; V-238 to S-278; V-239 to S-278; V-240 to S-278; H-241 to S-278 G-242 to S-278; L-243 to S-278; S-244 to S-278; A-245 to S-278; A-246 to S-278 D-247 to S-278; 1-248 to S-278; W-249 to S-278; L-250 to S-278; M-25Ϊ to S-278 W-252 to S-278; R-253 to S-278; L-254 to S-278; L-255 to S-278; H-256 to S-278 G-257 to S-278; P-258 to S-278; H-259 to S-278; G-260 to S-278; P-261 to S-278 A-262 to S-278; C-263 to S-278; A-264 to S-278; H-265 to S-278; P-266 to S-278 Q-267 to S-278; P-268 to S-278; V-269 to S-278; A-270 to S-278; A-271 to S-278 G-272 to S-278; or P-273 to S-278 of the Brainiac-5 sequence shown in Figures 1A and IB (SEQ ID NO:2). The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above polynucleotide sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molecules are also encompassed by the invention. Also as mentioned above, even if deletion of one or more amino acids from the C-terminus of a protein results in modification of loss of one or more biological functions of the protein, other biological activities may still be retained. Thus, the ability of the shortened Brainiac-5 mutein to induce and/or bind to antibodies which recognize the complete or mature forms of the polypeptide generally will be retained when less than the majority of the residues of the complete or mature polypeptide are removed from the C-terminus. Whether a particular polypeptide lacking C-terminal residues of a complete polypeptide retains such immunologic activities can readily be determined by routine methods described herein and otherwise known in the art. It is not unlikely that a Brainiac-5 mutein with a large number of deleted C-terminal amino acid residues may retain some biological or immunogenic activities. In fact, peptides composed of as few as six Brainiac-5 amino acid residues may often evoke an immune response. Accordingly, the present invention further provides polypeptides having one or more residues deleted from the carboxy terminus of the amino acid sequence of the Brainiac-5 polypeptide shown in Figures 1A and IB (SEQ ID NO:2), up to the glutamic acid residue at position number 6, and polynucleotides encoding such polypeptides. In particular, the present invention provides polypeptides comprising the amino acid sequence of residues 1-m 2 of Figures 1A and IB (SEQ ID NO:2), where πr is an integer in the range of 6 to 278, and 6 is the position of the first residue from the C-terminus of the complete Brainiac-5 polypeptide believed to be required for at least immunogenic activity of the Brainiac-5 polypeptide. More in particular, the invention provides nucleic acid molecules encoding polypeptides comprising, or alternatively consisting of, the amino acid sequence of residues V-l to D-277; V-l to W-276; V-l to Q-275; V-l to F-274; V-l to P-273; V-l to G-272; V-l to A-271; V-l to A-270; V-l to V-269; V-l to P-268; V-l to Q-267; V-l to P-266; V-l to H-265; V-l to A-264; V-l to C-263; V-l to A-262; V-l to P-261; V-l to G-260; V-l to H-259; V-l to P-258; V-l to G-257; V-l to H-256; V-l to L-255; V-l to L-254; V-l to R-253; V-l to W-252; V-l to M-251; V-l to L-250; V-l to W-249; V-l to 1-248; V-l to D-247; V-l to A-246; V-l to A-245; V-l to S-244; V-l to L-243; V-l to G-242; V-l to H-241; V-l to V-240; V-l to V-239; V-l to V-238; V-l to L-237; V-l to E-236; V-l to R-235; V-l to Y-234; V-l to F-233; V-l to C-232; V-l to P-231; V-l to D-230; V-l to F-229; V-l to T-228; V-l to S-227; V-l to L-226; V-l to H-225; V-l to P-224; V-l to A-223; V-l to A-222; V-l to S-221; V-l to P-220; V-l to Q-219; V-l to P-218; V-l to 1-217; V-l to G-216; V-l to F-215; V-l to T-214; V-l to R-213; V-l to F-212; V-l to A-211; V-l to P-210; V-l to H-209; V-l to P-208; V-l to E-207; V-l to P-206; V-l to T-205; V-l to L-204; V-l to R-203; V-l to L-202; V-l to R-201; V-l to Q-200; V-l to L-199; V-l to C-198; V-l to M-197; V-l to G-196; V-l to L-195; V-l to F-194; V-l to V-193; V-l to D-192; V-l to D-191; V-l to 1-190; V-l to P-189; V-l to F-188; V-l to L-187; V-l to E-186; V-l to V-185; V-l to Q-184; V-l to A-183; V-l to C-182; V-l to A-181; V-l to G-180; V-l to A-179; V-l to L-178; V-l to R-177; V-l to H-176; V-l to L-175; V-l to T-174; V-l to A-173; V-l to G-172; V-l to S-171; V-l to L-170; V-l to V-169; V-l to F-168; V-l to G-167; V-l to G-166; V-l to G-165; V-l to G-164; V-l to A-163; V-l to Y-162; V-l to A-161; V-l to P-160; V-l to Y-159; V-l to A-158; V-l to P-157; V-l to L-156; V-l to G-155; V-l to Y-154; V-l to V-153; V-l to A-152; V-l to E-151; V-l to P-150; V-l to 1-149; V-l to Y-148; V-l to Y-147; V-l to K-146; V-l to S-145; V-l to A-144; V-l to R-143; V-l to T-142; V-l to R-141; V-l to 1-140; V-l to P-139; V-l to R-138; V-l to A-137; V-l to H-136; V-l to V-135; V-l to 1-134; V-l to V-133; V-l to D-132; V-l to G-131; V-l to A-130; V-l to L-129; V-l to L-128; V-l to D-127; V-l to Q-126; V-l to A-125; V-l to P-124; V-l to D-123; V-l to R-122; V-l to P-121; V-l to A-120;V-ltoL-119;V-ltoF-118;V-l toE-117;V-l to L-l 16; V-l to L-l 15; V-l to N-114; V-l to G-l 13; V-l to V-l 12; V-l to N-111; V-l to V-l 10; V-l to F-109; V-l to V-108; V-l to D-107; V-l to A-106; V-l to D-105; V-l to G-104; V-l to K-103; V-l to F-102; V-l to V-101; V-l to F-100; V-l to R-99; V-l to V-98; V-l to D-97; V-l to P-96; V-l to C-95; V-l to F-94; V-l to A-93; V-l to S-92; V-l to A-91; V-l to W-90; V-l to A-89; V-l to L-88; V-l to F-87; V-l to H-86; V-l to 1-85; V-l to E-84; V-l to K-83; V-l to L-82; V-l to T-81; V-l to L-80; V-l to N-79; V-l to F-78; V-l to F-77; V-l to T-76; V-l to D-75; V-l to D-74; V-l to F-73; V-l to A-72; V-l to W-71; V-l to L-70; V-l to L-69; V-l to 1-68; V-l to D-67; V-l to A-66; V-l to Y-65; V-l to A-64; V-l to L-63; V-l to S-62; V-l to E-61; V-l to A-60; V-l to R-59; V-l to L-58; V-l to L-57; V-l to A-56; V-l to R-55; V-l to W-54; V-l to H-53; V-l to T-52; V-l to R-51; V-l to A-50; V-l to G-49; V-l to E-48; V-l to G-47; V-l to V-46; V-l to E-45; V-l to D-44; V-l to A-43; V-l to G-42; V-l to G-41; V-l to S-40; V-l to G-39; V-l to A-38; V-l to G-37; V-l to R-36; V-l to P-35; V-l to V-34; V-l to G-33; V-l to L-32; V-l to L-31; V-l to F-30; V-l to V-29; V-l to R-28; V-l to R-27; V-l to V-26; V-l to L-25; V-l to A-24; V-l to G-23; V-l to Q-22; V-l to V-21 ; V-l to R-20; V-l to G-19; V-l to E-18; V-l to A-17; V-l to G-16; V-l to W-15; V-l to T-14; V-l to Q-13; V-l to R-12; V-l to V-l 1; V-l to A-10; V-l to Q-9; V-l to R-8; V-l to R-7; or V-l to E-6 of the sequence of the Brainiac-5 sequence shown in Figures 1A and IB (SEQ ID NO:2). The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above polynucleotide sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molcules are also provided. The invention also provides nucleic acid molcules encoding polypeptides having (i.e., comprising, or alternatively consisting of) one or more amino acids deleted from both the amino and the carboxyl termini of a Brainiac-5 polypeptide, which may be described generally as having residues n 2 -m 2 of Figures 1A and IB (SEQ ID NO:2), where n 2 and m 2 are integers as described above. The present application is also directed to nucleic acid molecules comprising, or alternatively, consisting of, a polynucleotide sequence at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to the polynucleotide sequence encoding the Brainiac-5 polypeptides described above. The present invention also encompasses the above polynucleotide sequences fused to a heterologous polynucleotide sequence. Polypeptides encoded by these nucleic acid molecules are also provided by the invention. In addition to terminal deletion forms of the protein discussed above, it also will be recognized by one of ordinary skill in the art that some amino acid sequences of the Brainiac-5 polypeptides can be varied without significant effect of the structure or function of the protein. If such differences in sequence are contemplated, it should be remembered that there will be critical areas on the protein which determine activity. Thus, the invention further includes variations of the Brainiac-5 polypeptides which show substantial Brainiac-5 polypeptide activity or which include regions of Brainiac-5 polypeptides such as the polypeptide portions discussed below. Such mutants include deletions, insertions, inversions, repeats, and type substitutions selected according to general rules known in the art so as have little effect on activity. For example, guidance concerning how to make phenotypically silent amino acid substitutions is provided wherein the authors indicate that there are two main approaches for studying the tolerance of an amino acid sequence to change (Bowie, J. U., et al, Science 247:1306-1310 (1990)),. The first method relies on the process of evolution, in which mutations are either accepted or rejected by natural selection. The second approach uses genetic engineering to introduce amino acid changes at specific positions of a cloned gene and selections or screens to identify sequences that maintain functionality. As the authors state, these studies have revealed that proteins are suφrisingly tolerant of amino acid substitutions. The authors further indicate which amino acid changes are likely to be permissive at a certain position of the protein. For example, most buried amino acid residues require nonpolar side chains, whereas few features of surface side chains are generally conserved. Other such phenotypically silent substitutions are described by Bowie and coworkers (supra) and the references cited therein. Typically seen as conservative substitutions are the replacements, one for another, among the aliphatic amino acids Ala, Val, Leu and He; interchange of the hydroxyl residues Ser and Thr, exchange of the acidic residues Asp and Glu, substitution between the amide residues Asn and Gin, exchange of the basic residues Lys and Arg and replacements among the aromatic residues Phe, Tyr. Thus, the fragment, derivative or analog of the polypeptide of SEQ ID NO:2, or those encoded by the deposited cDNA, may be (i) one in which one or more of the amino acid residues are substituted with a conserved or non-conserved amino acid residue (preferably a conserved amino acid residue) and such substituted amino acid residue may or may not be one encoded by the genetic code, or (ii) one in which one or more of the amino acid residues includes a substituent group, or (iii) one in which either the Brainiac-5 mature polypeptide is fused with another compound, such as a compound to increase the half-life of the polypeptide (for example, polyethylene glycol), or (iv) one in which the additional amino acids are fused to the above form of the polypeptide, such as an IgG Fc fusion region peptide or leader or secretory sequence or a sequence which is employed for purification of the above form of the polypeptide or a proprotein sequence. Such fragments, derivatives and analogs are deemed to be within the scope of those skilled in the art from the teachings herein. Thus, the Brainiac-5 polypeptides of the present invention may include one or more amino acid substitutions, deletions or additions, either from natural mutations or human manipulation. As indicated, changes are preferably of a minor nature, such as conservative amino acid substitutions that do not significantly affect the folding or activity of the protein (see Table II). TABLE II. Conservative Amino Acid Substitutions. Amino acids in the Brainiac-5 polypeptides of the present invention that are essential for function can be identified by methods known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, Science 244:1081-1085 (1989)). The latter procedure introduces single alanine mutations at every residue in the molecule. The resulting mutant molecules are then tested for biological activity such as receptor binding or in vitro proliferative activity. Of special interest are substitutions of charged amino acids with other charged or neutral amino acids which may produce proteins with highly desirable improved characteristics, such as less aggregation. Aggregation may not only reduce activity but also be problematic when preparing pharmaceutical formulations, because aggregates can be immunogenic (Pinckard, et al, Clin. Exp. Immunol. 2:331-340 (1967); Robbins, et al, Diabetes 36:838-845 (1987); Cleland, et al, Crit. Rev. Therapeutic Drug Carrier Systems 10:307-377 (1993)). Replacement of amino acids can also change the selectivity of the binding of a ligand to cell surface receptors (for example, Ostade, et al, Nature 361:266-268 (1993)) describes certain mutations resulting in selective binding of TNF-alpha to only one of the two known types of TNF receptors. Sites that are critical for ligand- receptor binding can also be determined by structural analysis such as crystallization, nuclear magnetic resonance or photoaffinity labeling (Smith, et al, J. Mol. Biol. 224:899-904 (1992); de Vos, et al. Science 255:306-312 (1992)). Thus, the invention also encompasses Brainiac-5 derivatives and analogs that have one or more amino acid residues deleted, added, or substituted to generate Brainiac-5 polypeptides that are better suited for expression, scale up, etc., in the host cells chosen. For example, cysteine residues can be deleted or substituted with another amino acid residue in order to eliminate disulfide bridges; N-linked glycosylation sites can be altered or eliminated to achieve, for example, expression of a homogeneous product that is more easily recovered and purified from yeast hosts which are known to hyperglycosylate N-linked sites. To this end, a variety of amino acid substitutions at one or both of the first or third amino acid positions on any one or more of the glycosylation recognitions sequences in the Brainiac-5 polypeptides of the invention, and/or an amino acid deletion at the second position of any one or more such recognition sequences will prevent glycosylation of the Brainiac-5 at the modified tripeptide sequence (see, e.g., Miyajimo et al., EMBO J 5(6): 1193-1197). Additionally, one or more of the amino acid residues of the polypeptides of the invention (e.g., arginine and lysine residues) may be deleted or substituted with another residue to elminate undesired processing by proteases such as, for example, furins or kexins. The polypeptides of the present invention are preferably provided in an isolated form, and preferably are substantially purified. Recombinantly produced versions of the Brainiac-5 polypeptides can be substantially purified by the one-step method described by Smith and Johnson (Gene 67:31-40 (1988)). Polypeptides of the invention also can be purified from natural or recombinant sources using anti- Brainiac-5 antibodies of the invention in methods which are well known in the art of protein purification. Recombinant DNA technology known to those skilled in the art (see, for instance, DNA shuffling supra) can be used to create novel mutant proteins or muteins including single or multiple amino acid substitutions, deletions, additions or fusion proteins. Such modified polypeptides can show, e.g., enhanced activity or increased stability. In addition, they may be purified in higher yields and show better solubility than the coπesponding natural polypeptide, at least under certain purification and storage conditions. The invention also provides an isolated Brainiac-5 polypeptide comprising, or alternatively consisting of, an amino acid sequence selected from the group consisting of: (a) the amino acid sequence of the Brainiac-5 polypeptide having the complete amino acid sequence shown in SEQ ID NO:2 (i.e., positions 1-278 of SEQ ID NO:2); (b) the complete amino acid sequence encoded by the cDNA clone contained in the ATCC Deposit No. 203572; (c) the complete amino acid sequence of the predicted mature Brainiac-5 polypeptide encoded by the cDNA clone contained in the ATCC Deposit No. 203572. The polypeptides of the present invention also include polypeptides having an amino acid sequence at least 80% identical, more preferably at least 90% identical, and still more preferably 92%, 95%, 96%, 97%, 98% or 99% identical to those described in (a), (b) or (c), above, as well as polypeptides having an amino acid sequence with at least 90% similarity, and more preferably at least 95% similarity, to those above. Further polypeptides of the present invention include polypeptides which have (i.e., comprise, or alternatively consist of) at least 90% similarity, more preferably at least 92% similarity, more preferably at least 95% similarity, and still more preferably at least 96%, 97%, 98% or 99% similarity to those described above. The polypeptides of the invention also comprise those which are at least 80% identical, more preferably at least 90%, 92% or 95% identical, still more preferably at least 96%, 97%, 98% or 99% identical to the polypeptide encoded by the deposited cDNA or to the polypeptide of SEQ ID NO:2, and also include portions of such polypeptides with at least 15 amino acids, more preferably at least 30 amino acids, even more preferably at least 40 amino acids, still even more preferably at least 50 amino acids, still more preferably at least 60 amino acids, and yet even more preferably at least 75 amino acids. A further embodiment of the invention relates to a peptide or polypeptide which comprises the amino acid sequence of a Brainiac-5 polypeptide having an amino acid sequence which contains at least one conservative amino acid substitution, but not more than 50 conservative amino acid substitutions, even more preferably, not more than 40 conservative amino acid substitutions, still more preferably, not more than 30 conservative amino acid substitutions, and still even more preferably, not more than 20 conservative amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a peptide or polypeptide to have an amino acid sequence which comprises the amino acid sequence of a Brainiac-5 polypeptide, which contains at least one, but not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 conservative amino acid substitutions. Representative examples of polypeptide fragments of the invention, include, for example, fragments from about amino acid number 1-20, 21-40, 41-60, 61-80, 81-100, 101-120, 121-140, 141-160, 161-180, 181-200, 201-220, 221-240, 241-260, 261-278 or 261 to the end of the coding region of SEQ ID NO:2 or to a polypeptide expressed from the deposited cDNA clone which expresses Brainiac-5. Moreover, polypeptide fragments can be about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260 or 270 amino acids in length. In this context "about" includes the particularly recited ranges or values, and ranges or values larger or smaller by several (5, 4, 3, 2, or 1) amino acids, at either extreme or at both extremes. The invention also provides an isolated polypeptide comprising an amino acid sequence at least 90% identical to a sequence of at least about 10, 30 or 100 contiguous amino acids in the amino acid sequence of SEQ ID NO:2. By "% similarity" for two polypeptides is intended a similarity score produced by comparing the amino acid sequences of the two polypeptides using the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, WI 53711) and the default settings for determining similarity. Bestfit uses the local homology algorithm of Smith and Waterman (Advances in Applied Mathematics 2:482-489, 1981) to find the best segment of similarity between two sequences. In one embodiment of the invention, by a polypeptide having an amino acid sequence at least, for example, 95% "identical" to a reference amino acid sequence of a Brainiac-5 polypeptide is intended that the amino acid sequence of the polypeptide is identical to the reference sequence except that the polypeptide sequence may include up to five amino acid alterations per each 100 amino acids of the reference amino acid of the Brainiac-5 polypeptide. In other words, to obtain a polypeptide having an amino acid sequence at least 95% identical to a reference amino acid sequence, up to 5% of the amino acid residues in the reference sequence may be deleted or substituted with another amino acid, or a number of amino acids up to 5% of the total amino acid residues in the reference sequence may be inserted into the reference sequence. These alterations of the reference sequence may occur at the amino or carboxy terminal positions of the reference amino acid sequence or anywhere between those terminal positions, interspersed either individually among residues in the reference sequence or in one or more contiguous groups within the reference sequence. As a practical matter, whether any particular polypeptide is at least 90%, 92%, 95%, 96%, 97%, 98% or 99% identical to, for instance, the amino acid sequence shown in Figures 1A and IB (SEQ ID NO:2), the amino acid sequence encoded by deposited cDNA clone HOGCC45, or fragments thereof, can be determined conventionally using known computer programs such the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, WI 53711). When using Bestfit or any other sequence alignment program to determine whether a particular sequence is, for instance, 95% identical to a reference sequence according to the present invention, the parameters are set, of course, such that the percentage of identity is calculated over the full length of the reference amino acid sequence and that gaps in homology of up to 5% of the total number of amino acid residues in the reference sequence are allowed. In a specific embodiment, the identity between a reference (query) sequence (a sequence of the present invention) and a subject sequence, also referred to as a global sequence alignment, is determined using the FASTDB computer program based on the algorithm of Brutlag et al. (Comp. App. Biosci. 6:237-245 (1990)). Preferred parameters used in a FASTDB amino acid alignment are: Matrix=PAM 0, k-tuple=2, Mismatch Penalty=l, Joining Penalty=20, Randomization Group Length=0, Cutoff Score=l, Window Size=sequence length, Gap Penalty=5, Gap Size Penalty=0.05, Window Size=500 or the length of the subject amino acid sequence, whichever is shorter. According to this embodiment, if the subject sequence is shorter than the query sequence due to N- or C-terminal deletions, not because of internal deletions, a manual correction is made to the results to take into consideration the fact that the FASTDB program does not account for N- and C-terminal truncations of the subject sequence when calculating global percent identity. For subject sequences truncated at the N- and C-termini, relative to the query sequence, the percent identity is corrected by calculating the number of residues of the query sequence that are N- and C-terminal of the subject sequence, which are not matched/aligned with a corresponding subject residue, as a percent of the total bases of the query sequence. A determination of whether a residue is matched/aligned is determined by results of the FASTDB sequence alignment. This percentage is then subtracted from the percent identity, calculated by the above FASTDB program using the specified parameters, to arrive at a final percent identity score. This final percent identity score is what is used for the puφoses of this embodiment. Only residues to the N- and C-termini of the subject sequence, which are not matched/aligned with the query sequence, are considered for the purposes of manually adjusting the percent identity score. That is, only query residue positions outside the farthest N- and C-terminal residues of the subject sequence. For example, a 90 amino acid residue subject sequence is aligned with a 100 residue query sequence to determine percent identity. The deletion occurs at the N-terminus of the subject sequence and therefore, the FASTDB alignment does not show a matching/alignment of the first 10 residues at the N-terminus. The 10 unpaired residues represent 10% of the sequence (number of residues at the N- and C- termini not matched/total number of residues in the query sequence) so 10% is subtracted from the percent identity score calculated by the FASTDB program. If the remaining 90 residues were perfectly matched the final percent identity would be 90%. In another example, a 90 residue subject sequence is compared with a 100 residue query sequence. This time the deletions are internal deletions so there are no residues at the N- or C-termini of the subject sequence which are not matched/aligned with the query. In this case the percent identity calculated by FASTDB is not manually corrected. Once again, only residue positions outside the N- and C-terminal ends of the subject sequence, as displayed in the FASTDB alignment, which are not matched/aligned with the query sequence are manually corrected for. No other manual corrections are made for the puφoses of this embodiment. The polypeptide of the present invention could be used, for example, as a molecular weight marker on SDS-PAGE gels or on molecular sieve gel filtration columns using methods well known to those of skill in the art. As described in detail below, the polypeptides of the present invention can also be used to raise polyclonal and monoclonal antibodies, which are useful in assays for detecting Brainiac-5 polypeptide expression as described below or as agonists and antagonists capable of enhancing or inhibiting Brainiac-5 polypeptide function. Further, such polypeptides can be used in the yeast two-hybrid system to "capture" Brainiac-5 polypeptide-binding polypeptides which are also candidate agonists and antagonists according to the present invention. The yeast two hybrid system is described by Fields and Song (Nature 340:245-246 (1989)). Transgenics and "knock-outs" The polypeptides of the invention can also be expressed in transgenic animals. Animals of any species, including, but not limited to, mice, rats, rabbits, hamsters, guinea pigs, pigs, micro-pigs, goats, sheep, cows and non-human primates, e.g., baboons, monkeys, and chimpanzees may be used to generate transgenic animals. In a specific embodiment, techniques described herein or otherwise known in the art, are used to express polypeptides of the invention in humans, as part of a gene therapy protocol. Any technique known in the art may be used to introduce the transgene (i.e., polynucleotides of the invention) into animals to produce the founder lines of transgenic animals. Such techniques include, but are not limited to, pronuclear microinjection (Paterson, et al, Appl Microbiol Biotechnol. 40:691-698 (1994); Carver et al., Biotechnology (NY) 11:1263-1270 (1993); Wright et al., Biotechnology (NY) 9:830-834 (1991); and Hoppe et al., U.S. Pat. No. 4,873,191 (1989)); retrovirus mediated gene transfer into germ lines (Van der Putten et al., Proc. Natl. Acad. Sci., USA 82:6148-6152 (1985)), blastocysts or embryos; gene targeting in embryonic stem cells (Thompson et al., Cell 56:313-321 (1989)); electroporation of cells or embryos (Lo, 1983, Mol Cell. Biol. 3:1803-1814 (1983)); introduction of the polynucleotides of the invention using a gene gun (see, e.g., Ulmer et al., Science 259:1745 (1993); introducing nucleic acid constructs into embryonic pleuripotent stem cells and transferring the stem cells back into the blastocyst; and sperm-mediated gene transfer (Lavitrano et al., Cell 57:717-723 (1989); etc. For a review of such techniques, see Gordon, "Transgenic Animals," Intl. Rev. Cytol. 115:171-229 (1989), which is incoφorated by reference herein in its entirety. See also, U.S. Patent No. 5,464,764 (Capecchi, et al., Positive-Negative Selection Methods and Vectors); U.S. Patent No. 5,631,153 (Capecchi, et al., Cells and Non-Human Organisms Containing Predetermined Genomic Modifications and Positive-Negative Selection Methods and Vectors for Making Same); U.S. Patent No. 4,736,866 (Leder, et al., Transgenic Non- Human Animals); and U.S. Patent No. 4,873,191 (Wagner, et al., Genetic Transformation of Zygotes); each of which is hereby incoφorated by reference in its entirety. Any technique known in the art may be used to produce transgenic clones containing polynucleotides of the invention, for example, nuclear transfer into enucleated oocytes of nuclei from cultured embryonic, fetal, or adult cells induced to quiescence (Campell et al., Nature 380:64-66 (1996); Wilmut et al., Nature 385:810- 813 (1997)). The present invention provides for transgenic animals that carry the transgene in all their cells, as well as animals which carry the transgene in some, but not all their cells, i.e., mosaic or chimeric animals. The transgene may be integrated as a single transgene or as multiple copies such as in concatamers, e.g., head-to-head tandems or head-to-tail tandems. The transgene may also be selectively introduced into and activated in a particular cell type by following, for example, the teaching of Lasko et al. (Lasko et al., Proc. Natl. Acad. Sci. USA 89:6232-6236 (1992)). The regulatory sequences required for such a cell-type specific activation will depend upon the particular cell type of interest, and will be apparent to those of skill in the art. When it is desired that the polynucleotide transgene be integrated into the chromosomal site of the endogenous gene, gene targeting is preferred. Briefly, when such a technique is to be utilized, vectors containing some nucleotide sequences homologous to the endogenous gene are designed for the puφose of integrating, via homologous recombination with chromosomal sequences, into and disrupting the function of the nucleotide sequence of the endogenous gene. The transgene may also be selectively introduced into a particular cell type, thus inactivating the endogenous gene in only that cell type, by following, for example, the teaching of Gu et al. (Gu et al., Science 265:103-106 (1994)). The regulatory sequences required for such a cell-type specific inactivation will depend upon the particular cell type of interest, and will be apparent to those of skill in the art. In addition to expressing the polypeptide of the present invention in a ubiquitous or tissue specific manner in transgenic animals, it would also be routine for one skilled in the art to generate constructs which regulate expression of the polypeptide by a variety of other means (for example, developmentally or chemically regulated expression). Once transgenic animals have been generated, the expression of the recombinant gene may be assayed utilizing standard techniques. Initial screening may be accomplished by Southern blot analysis or PCR techniques to analyze animal tissues to verify that integration of the transgene has taken place. The level of mRNA expression of the transgene in the tissues of the transgenic animals may also be assessed using techniques which include, but are not limited to, Northern blot analysis of tissue samples obtained from the animal, in situ hybridization analysis, and reverse transcriptase-PCR (rt-PCR). Samples of transgenic gene-expressing tissue may also be evaluated immunocytochemically or immunohistochemically using antibodies specific for the transgene product. Once the founder animals are produced, they may be bred, inbred, outbred, or crossbred to produce colonies of the particular animal. Examples of such breeding strategies include, but are not limited to: outbreeding of founder animals with more than one integration site in order to establish separate lines; inbreeding of separate lines in order to produce compound transgenics that express the transgene at higher levels because of the effects of additive expression of each transgene; crossing of heterozygous transgenic animals to produce animals homozygous for a given integration site in order to both augment expression and eliminate the need for screening of animals by DNA analysis; crossing of separate homozygous lines to produce compound heterozygous or homozygous lines; and breeding to place the transgene on a distinct background that is appropriate for an experimental model of interest. Transgenic and "knock-out" animals of the invention have uses which include, but are not limited to, animal model systems useful in elaborating the biological function of Brainiac-5 polypeptides, studying conditions and/or disorders associated with aberrant Brainiac-5 expression, and in screening for compounds effective in ameliorating such conditions and/or disorders. In further embodiments of the invention, cells that are genetically engineered to express the polypeptides of the invention, or alternatively, that are genetically engineered not to express the polypeptides of the invention (e.g., knockouts) are administered to a patient in vivo. Such cells may be obtained from the patient (i.e., animal, including human) or an MHC compatible donor and can include, but are not limited to fibroblasts, bone marrow cells, blood cells (e.g., lymphocytes), adipocytes, muscle cells, endothelial cells etc. The cells are genetically engineered in vitro using recombinant DNA techniques to introduce the coding sequence of polypeptides of the invention into the cells, or alternatively, to disrupt the coding sequence and/or endogenous regulatory sequence associated with the polypeptides of the invention, e.g., by transduction (using viral vectors, and preferably vectors that integrate the transgene into the cell genome) or transfection procedures, including, but not limited to, the use of plasmids, cosmids, YACs, naked DNA, electroporation, liposomes, etc. The coding sequence of the polypeptides of the invention can be placed under the « control of a strong constitutive or inducible promoter or promoter/enhancer to achieve expression, and preferably secretion, of the polypeptides of the invention. The engineered cells which express and preferably secrete the polypeptides of the invention can be introduced into the patient systemically, e.g., in the circulation, or intraperitoneally. Alternatively, the cells can be incoφorated into a matrix and implanted in the body, e.g., genetically engineered fibroblasts can be implanted as part of a skin graft; genetically engineered endothelial cells can be implanted as part of a lymphatic or vascular graft. (See, for example, Anderson et al. U.S. Patent No. 5,399,349; and Mulligan & Wilson, U.S. Patent No. 5,460,959 each of which is incoφorated by reference herein in its entirety). When the cells to be administered are non-autologous or non-MHC compatible cells, they can be administered using well known techniques which prevent the development of a host immune response against the introduced cells. For example, the cells may be introduced in an encapsulated form which, while allowing for an exchange of components with the immediate extracellular environment, does not allow the introduced cells to be recognized by the host immune system. Antibodies The present invention further relates to antibodies and T-cell antigen receptors (TCR) which immunospecifically bind a polypeptide, preferably an epitope, of the present invention (as determined by immunoassays well known in the art for assaying specific antibody-antigen binding). Antibodies of the invention include, but are not limited to, polyclonal, monoclonal, multispecific, human, humanized or chimeric antibodies, single chain antibodies, Fab fragments, F(ab') fragments, fragments produced by a Fab expression library, anti-idiotypic (anti-Id) antibodies (including, e.g., anti-Id antibodies to antibodies of the invention), and epitope-binding fragments of any of the above. The term "antibody," as used herein, refers to immunoglobuhn molecules and immunologically active portions of immunoglobuhn molecules, i.e., molecules that contain an antigen binding site that immunospecifically binds an antigen. The immunoglobuhn molecules of the invention can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgGl, IgG2, IgG3, IgG4, IgAl and IgA2) or subclass of immunoglobuhn molecule. Most preferably the antibodies are human antigen-binding antibody fragments of the present invention and include, but are not limited to, Fab, Fab' and F(ab')2, Fd, single-chain Fvs (scFv), single-chain antibodies, disulfide-linked Fvs (sdFv) and fragments comprising either a VL or VH domain. Antigen-binding antibody fragments, including single-chain antibodies, may comprise the variable region(s) alone or in combination with the entirety or a portion of the following: hinge region, CHI, CH2, and CH3 domains. Also included in the invention are antigen-binding fragments also comprising any combination of variable region(s) with a hinge region, CHI, CH2, and CH3 domains. The antibodies of the invention may be from any animal origin including birds and mammals. Preferably, the antibodies are human, murine, donkey, ship rabbit, goat, guinea pig, camel, horse, or chicken. As used herein, "human" antibodies include antibodies having the amino acid sequence of a human immunoglobuhn and include antibodies isolated from human immunoglobuhn libraries or from animals transgenic for one or more human immunoglobuhn and that do not express endogenous immunoglobulins, as described infra and, for example in, U.S. Patent No. 5,939,598 by Kucherlapati et al. The antibodies of the present invention may be monospecific, bispecific, trispecific or of greater multispecificity. Multispecific antibodies may be specific for different epitopes of a polypeptide of the present invention or may be specific for both a polypeptide of the present invention as well as for a heterologous epitope, such as a heterologous polypeptide or solid support material. See, e.g., PCT publications WO 93/17715; WO 92/08802; WO 91/00360; WO 92/05793; Tutt, et al., J. Immunol. 147:60-69 (1991); U.S. Patent Nos. 4,474,893; 4,714,681 ; 4,925,648; 5,573,920; 5,601,819; Kostelny et al., J. Immunol. 148: 1547-1553 (1992). Antibodies of the present invention may be described or specified in terms of the epitope(s) or portion(s) of a polypeptide of the present invention that they recognize or specifically bind. The epitope(s) or polypeptide portion(s) may be specified as described herein, e.g., by N-terminal and C-terminal positions, by size in contiguous amino acid residues, or listed in the Tables and Figures. Antibodies that < specifically bind any epitope or polypeptide of the present invention may also be excluded. Therefore, the present invention includes antibodies that specifically bind polypeptides of the present invention, and allows for the exclusion of the same. Antibodies of the present invention may also be described or specified in terms of their cross-reactivity. Antibodies that do not bind any other analog, ortholog, or homolog of a polypeptide of the present invention are included. Antibodies that bind polypeptides with at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 65%, at least 60%, at least 55%, and at least 50% identity (as calculated using methods known in the art and described herein) to a polypeptide of the present invention are also included in the present invention. Antibodies that do not bind polypeptides with less than 95%, less than 90%, less than 85%, less than 80%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, and less than 50% identity (as calculated using methods known in the art and described herein) to a polypeptide of the present invention are also included in the present invention. Further included in the present invention are antibodies that bind polypeptides encoded by polynucleotides which hybridize to a polynucleotide of the present invention under stringent hybridization conditions (as described herein). Antibodies of the present invention may also be described or specified in terms of their binding affinity to a polypeptide of the invention. Preferred binding affinities include those with a dissociation constant or Kd less than 5X 10 "2 M, 10 "2 M, 5X 10 "3 M, 10 " M, 5X 10 "4 M, 10 " 4 M, 5X10 "5 M, 10 "5 M, 5X10 "6 M, 10 "6 M, 5X10 "7 M, 10 "7 M, 5X10 "8 M, 10 "8 M, 5X10 "9 M, 10 " 9 M, 5X10 10 M, 10 10 M, 5X10"M, 10"M, 5X10 12 M, 10 I2 M, 5X10 I3 M, 10 13 M, 5X10 " 14 M, 10 14 M, 5X10 ',5 M, and 10 15 M. The invention also provides antibodies that competitively inhibit binding of an antibody to an epitope of the invention as determined by any method known in the art for determining competitive binding, for example, the immunoassays described herein. In prefeπed embodiments, the antibody competitively inhibits binding to the epitope by at least 90%, at least 80%, at least 70%, at least 60%, or at least 50%. Antibodies of the present invention may act as agonists or antagonists of the polypeptides of the present invention. For example, the present invention includes antibodies which disrupt the receptor/ligand interactions with the polypeptides of the invention either partially or fully. The invention features both receptor-specific antibodies and ligand-specific antibodies. The invention also features receptor- specific antibodies which do not prevent ligand binding but prevent receptor activation. Receptor activation (i.e., signaling) may be determined by techniques described herein or otherwise known in the art. For example, receptor activation can be determined by detecting the phosphorylation (e.g., tyrosine or serine/threonine) of the receptor or its substrate by immunoprecipitation followed by western blot analysis (for example, as described supra). In specific embodiments, antibodies are provided that inhibit ligand or receptor activity by at least 90%, at least 80%, at least 70%, at least 60%, or at least 50% of the activity in absence of the antibody. The invention also features receptor-specific antibodies which both prevent ligand binding and receptor activation as well as antibodies that recognize the receptor-ligand complex, and, preferably, do not specifically recognize the unbound receptor or the unbound ligand. Likewise, included in the invention are neutralizing antibodies which bind the ligand and prevent binding of the ligand to the receptor, as well as antibodies which bind the ligand, thereby preventing receptor activation, but do not prevent the ligand from binding the receptor. Further included in the invention are antibodies which activate the receptor. These antibodies may act as receptor agonists, i.e., potentiate or activate either all or a subset of the biological activities of the ligand-mediated receptor activation. The antibodies may be specified as agonists, antagonists or inverse agonists for biological activities comprising the specific biological activities of the peptides of the invention disclosed herein. The above antibody agonists can be made using methods known in the art. See, e.g., PCT publication WO 96/40281; U.S. Patent No. 5,811,097; Deng et al., Blood 92(6):1981- 1988 (1998); Chen, et al., Cancer Res. 58(16):3668-3678 (1998); Harrop et al., J. Immunol. 161 (4): 1786- 1794 (1998); Zhu et al., Cancer Res. 58(15):3209-3214 (1998); Yoon, et al., J. Immunol. 160(7):3170-3179 (1998); Prat et al., J. Cell. Sci. 1 l l(Pt2):237-247 (1998); Pitard et al., J. Immunol. Methods 205(2): 177-190 (1997); Liautard et al., Cytokine 9(4):233-241 (1997); Carlson et al., J. Biol. Chem. 272(17):11295-11301 (1997); Taryman et al., Neuron 14(4):755-762 (1995); Muller et al., Structure 6(9): 1153-1167 (1998); Bartunek et al., Cytokine 8(1): 14-20 (1996) (which are all incoφorated by reference herein in their entireties). Antibodies of the present invention may be used, for example, but not limited to, to purify, detect, and target the polypeptides of the present invention, including both in vitro and in vivo diagnostic and therapeutic methods. For example, the antibodies have use in immunoassays for qualitatively and quantitatively measuring levels of the polypeptides of the present invention in biological samples. See, e.g., Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988) (incoφorated by reference herein in its entirety). As discussed in more detail below, the antibodies of the present invention may be used either alone or in combination with other compositions. The antibodies may further be recombinantly fused to a heterologous polypeptide at the N- or C-terminus or chemically conjugated (including covalently and non-covalently conjugations) to polypeptides or other compositions. For example, antibodies of the present invention may be recombinantly fused or conjugated to molecules useful as labels in detection assays and effector molecules such as heterologous polypeptides, drugs, or toxins. See, e.g., PCT publications WO 92/08495; WO 91/14438; WO 89/12624; U.S. Patent No. 5,314,995; and EP 396,387. The antibodies of the invention include derivatives that are modified, i.e, by the covalent attachment of any type of molecule to the antibody such that covalent attachment does not prevent the antibody from generating an anti-idiotypic response. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. The antibodies of the present invention may be generated by any suitable method known in the art. Polyclonal antibodies to an antigen-of- interest can be produced by various procedures well known in the art. For example, a polypeptide of the invention can be administered to various host animals including, but not limited to, rabbits, mice, rats, etc. to induce the production of sera containing polyclonal antibodies specific for the antigen. Various adjuvants may be used to increase the immunological response, depending on the host species, and include but are not limited to, Freund's (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanins, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and corynebacterium parvum. Such adjuvants are also well known in the art. Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof. For example, monoclonal antibodies can be produced using hybridoma techniques including those known in the art and taught, for example, in Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988); Hammerling, et al., in: Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, N.Y., 1981) (said references incoφorated by reference in their entireties). The term "monoclonal antibody" as used herein is not limited to antibodies produced through hybridoma technology. The term "monoclonal antibody" refers to an antibody that is derived from a single clone, including any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced. Methods for producing and screening for specific antibodies using hybridoma technology are routine and well-known in the art and are discussed in detail in Example 5. Briefly, mice can be immunized with a polypeptide of the invention or a cell expressing such peptide. Once an immune response is detected, e.g., antibodies specific for the antigen are detected in the mouse serum, the mouse spleen is harvested and splenocytes isolated. The splenocytes are then fused by well-known techniques to any suitable myeloma cells, for example cells from cell line SP20 available from the ATCC. Hybridomas are selected and cloned by limited dilution. The hybridoma clones are then assayed by methods known in the art for cells that secrete antibodies capable of binding a polypeptide of the invention. Ascites fluid, which generally contains high levels of antibodies, can be generated by immunizing mice with positive hybridoma clones. Accordingly, the present invention provides methods of generating monoclonal antibodies as well as antibodies produced by the method comprising culturing a hybridoma cell secreting an antibody of the invention wherein, preferably, the hybridoma is generated by fusing splenocytes isolated from a mouse immunized with an antigen of the invention with myeloma cells and then screening the hybridomas resulting from the fusion for hybridoma clones that secrete an antibody able to bind a polypeptide of the invention. Antibody fragments that recognize specific epitopes may be generated by known techniques. For example, Fab and F(ab')2 fragments of the invention may be produced by proteolytic cleavage of immunoglobuhn molecules, using enzymes such as papain (to produce Fab fragments) or pepsin (to produce F(ab')2 fragments). F(ab')2 fragments contain the variable region, the light chain constant region and the CHI domain of the heavy chain. For example, the antibodies of the present invention can also be generated using various phage display methods known in the art. In phage display methods, functional antibody domains are displayed on the surface of phage particles which carry the polynucleotide sequences encoding them. In a particular, such phage can be utilized to display antigen-binding domains expressed from a repertoire or combinatorial antibody library (e.g., human or murine). Phage expressing an antigen binding domain that binds the antigen of interest can be selected or identified with antigen, e.g., using labeled antigen or antigen bound or captured to a solid surface or bead. Phage used in these methods are typically filamentous phage including fd and M13 binding domains expressed from phage with Fab, Fv or disulfϊde stabilized Fv antibody domains recombinantly fused to either the phage gene III or gene VIII protein. Examples of phage display methods that can be used to make the antibodies of the present invention include those disclosed in Brinkman et al., J. Immunol. Methods 182:41-50 (1995); Ames et al., J. Immunol. Methods 184:177-186 (1995); Kettleborough et al., Eur. J. Immunol. 24:952-958 (1994); Persic et al., Gene 187 9-18 (1997); Burton et al., Advances in Immunology 57:191-280 (1994); PCT application No. PCT/GB91/01134; PCT publications WO 90/02809; WO 91/10737; WO 92/01047; WO 92/18619; WO 93/11236; WO 95/15982; WO 95/20401; and U.S. Patent Nos. 5,698,426; 5,223,409; 5,403,484; 5,580,717; 5,427,908; 5,750,753; 5,821,047; 5,571,698; 5,427,908; 5,516,637; 5,780,225; 5,658,727; 5,733,743 and 5,969,108; each of which is incoφorated herein by reference in its entirety. As described in the above references, after phage selection, the antibody coding regions from the phage can be isolated and used to generate whole antibodies, including human antibodies, or any other desired antigen binding fragment, and expressed in any desired host, including mammalian cells, insect cells, plant cells, yeast, and bacteria, e.g., as described in detail below. For example, techniques to recombinantly produce Fab, Fab' and F(ab')2 fragments can also be employed using methods known in the art such as those disclosed in PCT publication WO 92/22324; Mullinax et al., BioTechniques 12(6):864-869 (1992); and Sawai et al., AJRI 34:26- 34 (1995); and Better et al., Science 240:1041-1043 (1988) (said references incoφorated by reference in their entireties). Examples of techniques which can be used to produce single-chain Fvs and antibodies include those described in U.S. Patents 4,946,778 and 5,258,498; Huston et al., Methods in Enzymology 203:46-88 (1991); Shu et al., PNAS 90:7995-7999 (1993); and Skerra et al., Science 240:1038-1040 (1988). For some uses, including in vivo use of antibodies in humans and in vitro detection assays, it may be preferable to use chimeric, humanized, or human antibodies. A chimeric antibody is a molecule in which different portions of the antibody are derived from different animal species, such as antibodies having a variable region derived from a murine monoclonal antibody and a human immunoglobuhn constant region. Methods for producing chimeric antibodies are known in the art. See e.g., Morrison, Science 229: 1202 (1985); Oi et al., BioTechniques 4:214 (1986); Gillies et al., (1989) J. Immunol. Methods 125:191-202; U.S. Patent Nos. 5,807,715; 4,816,567; and 4,816397, which are incoφorated herein by reference in their entireties. Humanized antibodies are antibody molecules from non-human species antibody that binds the desired antigen having one or more complementarity determining regions (CDRs) from the non- human species and framework regions from a human immunoglobuhn molecule. Often, framework residues in the human framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. (See, e.g., Queen et al., U.S. Patent No. 5,585,089; Riechmann et al., Nature 332:323 (1988), which are incoφorated herein by reference in their entireties.) Antibodies can be humanized using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; PCT publication WO 91/09967; U.S. Patent Nos. 5,225,539; 5,530,101; and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, Molecular Immunology 28(4/5):489-498 (1991); Studnicka et al., Protein Engineering 7(6):805- 814 (1994); Roguska. et al., PNAS 91:969-973 (1994)), and chain shuffling (U.S. Patent No. 5,565,332). Completely human antibodies are particularly desirable for therapeutic treatment of human patients. Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobuhn sequences. See also, U.S. Patent Nos. 4,444,887 and 4,716,111; and PCT publications WO 98/46645, WO 98/50433, WO 98/24893, WO 98/16654, WO 96/34096, WO 96/33735, and WO 91/10741; each of which is incoφorated herein by reference in its entirety. Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobuhn genes. For example, the human heavy and light chain immunoglobuhn gene complexes may be introduced randomly or by homologous recombination into mouse embryonic stem cells. Alternatively, the human variable region, constant region, and diversity region may be introduced into mouse embryonic stem cells in addition to the human heavy and light chain genes. The mouse heavy and light chain immunoglobuhn genes may be rendered non-functional separately or simultaneously with the introduction of human immunoglobuhn loci by homologous recombination. In particular, homozygous deletion of the JH region prevents endogenous antibody production. The modified embryonic stem cells are expanded and microinjected into blastocysts to produce chimeric mice. The chimeric mice are then bred to produce homozygous offspring that express human antibodies. The transgenic mice are immunized in the normal fashion with a selected antigen, e.g., all or a portion of a polypeptide of the invention. Monoclonal antibodies directed against the antigen can be obtained from the immunized, transgenic mice using conventional hybridoma technology. The human immunoglobuhn transgenes harbored by the transgenic mice reaπange during B cell differentiation, and subsequently undergo class switching and somatic mutation. Thus, using such a technique, it is possible to produce therapeutically useful IgG, IgA, IgM and IgE antibodies. For an overview of this technology for producing human antibodies, see Lonberg and Huszar (1995, Int. Rev. Immunol. 13:65-93). For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., PCT publications WO 98/24893; WO 96/34096; WO 96/33735; U.S. Patent Nos. 5,413,923; 5,625,126; 5,633,425; 5,569,825; 5,661,016; 5,545,806; 5,814,318; and 5,939,598, which are incoφorated by reference herein in their entirety. In addition, companies such as Abgenix, Inc. (Freemont, CA) and Genpharm (San Jose, CA) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above. Completely human antibodies which recognize a selected epitope can be generated using a technique referred to as "guided selection." In this approach a selected non-human monoclonal antibody, e.g., a mouse antibody, is used to guide the selection of a completely human antibody recognizing the same epitope. (Jespers et al., Bio/technology 12:899-903 (1988)). Further, antibodies to the polypeptides of the invention can, in turn, be utilized to generate anti-idiotype antibodies that "mimic" polypeptides of the invention using techniques well known to those skilled in the art. (See, e.g., Greenspan & Bona, FASEB J. 7(5):437-444; (1989) and Nissinoff, J. Immunol. 147(8):2429-2438 (1991)). For example, antibodies which bind to and competitively inhibit polypeptide multimerization and/or binding of a polypeptide of the invention to a ligand can be used to generate anti-idiotypes that "mimic" the polypeptide multimerization and/or binding domain and, as a consequence, bind to and neutralize polypeptide and/or its ligand. Such neutralizing anti-idiotypes or Fab fragments of such anti-idiotypes can be used in therapeutic regimens to neutralize polypeptide ligand. For example, such anti- idiotypic antibodies can be used to bind a polypeptide of the invention and/or to bind its ligands/receptors, and thereby block its biological activity. Polynucleotides Encoding Antibodies. The invention further provides polynucleotides comprising a nucleotide sequence encoding an antibody of the invention and fragments thereof. The invention also encompasses polynucleotides that hybridize under stringent or lower stringency hybridization conditions, e.g., as defined supra, to polynucleotides that encode an antibody, preferably, that specifically binds to a polypeptide of the invention, preferably, an antibody that binds to a polypeptide having the amino acid sequence of SEQ ID NO:2. The polynucleotides may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. For example, if the nucleotide sequence of the antibody is known, a polynucleotide encoding the antibody may be assembled from chemically synthesized ohgonucleotides (e.g., as described in Kutmeier et al., BioTechniques 17:242 (1994)), which, briefly, involves the synthesis of overlapping ohgonucleotides containing portions of the sequence encoding the antibody, annealing and ligation of those ohgonucleotides, and then amplification of the ligated ohgonucleotides by PCR. Alternatively, a polynucleotide encoding an antibody may be generated from nucleic acid from a suitable source. If a clone containing a nucleic acid encoding a particular antibody is not available, but the sequence of the antibody molecule is known, a nucleic acid encoding the immunoglobuhn may be obtained from a suitable source (e.g., an antibody cDNA library, or a cDNA library generated from, or nucleic acid, preferably poly A+ RNA, isolated from, any tissue or cells expressing the antibody, such as hybridoma cells selected to express an antibody of the invention) by PCR amplification using synthetic primers hybridizable to the 3' and 5' ends of the sequence or by cloning using an ohgonucleotide probe specific for the particular gene sequence to identify, e.g., a cDNA clone from a cDNA library that encodes the antibody. Amplified nucleic acids generated by PCR may then be cloned into replicable cloning vectors using any method well known in the art. Once the nucleotide sequence and corresponding amino acid sequence of the antibody is determined, the nucleotide sequence of the antibody may be manipulated using methods well known in the art for the manipulation of nucleotide sequences, e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et al., 1990, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, NY and Ausubel et al., eds., 1998, Current Protocols in Molecular Biology, John Wiley & Sons, NY, which are both incoφorated by reference herein in their entireties ), to generate antibodies having a different amino acid sequence, for example to create amino acid substitutions, deletions, and/or insertions. In a specific embodiment, the amino acid sequence of the heavy and/or light chain variable domains may be inspected to identify the sequences of the complementarity determining regions (CDRs) by methods that are well know in the art, e.g., by comparison to known amino acid sequences of other heavy and light chain variable regions to determine the regions of sequence hypervariability. Using routine recombinant DNA techniques, one or more of the CDRs may be inserted within framework regions, e.g., into human framework regions to humanize a non-human antibody, as described supra. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et al., J. Mol. Biol. 278: 457-479 (1998) for a listing of human framework regions). Preferably, the polynucleotide generated by the combination of the framework regions and CDRs encodes an antibody that specifically binds a polypeptide of the invention. Preferably, as discussed supra, one or more amino acid substitutions may be made within the framework regions, and, preferably, the amino acid substitutions improve binding of the antibody to its antigen. Additionally, such methods may be used to make amino acid substitutions or deletions of one or more variable region cysteine residues participating in an intrachain disulfide bond to generate antibody molecules lacking one or more intrachain disulfide bonds. Other alterations to the polynucleotide are encompassed by the present invention and within the skill of the art. In addition, techniques developed for the production of "chimeric antibodies" (Morrison et al., 1984, Proc. Natl. Acad. Sci. 81 :851-855; Neuberger et al., 1984, Nature 312:604-608; Takeda et al., 1985, Nature 314:452-454) by splicing genes from a mouse antibody molecule of appropriate antigen specificity together with genes from a human antibody molecule of appropriate biological activity can be used. As described supra, a chimeric antibody is a molecule in which different portions are derived from different animal species, such as those having a variable region derived from a murine mAb and a human immunoglobuhn constant region, e.g., humanized antibodies. Alternatively, techniques described for the production of single chain antibodies (U.S. Patent No. 4,694,778; Bird, 1988, Science 242:423- 42; Huston et al., 1988, Proc. Natl. Acad. Sci. USA 85:5879-5883; and Ward et al., 1989, Nature 334:544-54) can be adapted to produce single chain antibodies. Single chain antibodies are formed by linking the heavy and light chain fragments of the Fv region via an amino acid bridge, resulting in a single chain polypeptide. Techniques for the assembly of functional Fv fragments in E. coli may also be used (Skerra et al., 1988, Science 242:1038- 1041). Methods of Producing Antibodies. The antibodies of the invention can be produced by any method known in the art for the synthesis of antibodies, in particular, by chemical synthesis or preferably, by recombinant expression techniques. Recombinant expression of an antibody of the invention, or fragment, derivative or analog thereof, e.g., a heavy or light chain of an antibody of the invention, requires construction of an expression vector containing a polynucleotide that encodes the antibody. Once a polynucleotide encoding an antibody molecule or a heavy or light chain of an antibody, or portion thereof (preferably containing the heavy or light chain variable domain), of the invention has been obtained, the vector for the production of the antibody molecule may be produced by recombinant DNA technology using techniques well known in the art. Thus, methods for preparing a protein by expressing a polynucleotide containing an antibody encoding nucleotide sequence are described herein. Methods which are well known to those skilled in the art can be used to construct expression vectors containing antibody coding sequences and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. The invention, thus, provides replicable vectors comprising a nucleotide sequence encoding an antibody molecule of the invention, or a heavy or light chain thereof, or a heavy or light chain variable domain, operably linked to a promoter. Such vectors may include the nucleotide sequence encoding the constant region of the antibody molecule (see, e.g., PCT Publication WO 86/05807; PCT Publication WO 89/01036; and U.S. Patent No. 5,122,464) and the variable domain of the antibody may be cloned into such a vector for expression of the entire heavy or light chain. The expression vector is transfeπed to a host cell by conventional techniques and the transfected cells are then cultured by conventional techniques to produce an antibody of the invention. Thus, the invention includes host cells containing a polynucleotide encoding an antibody of the invention, or a heavy or light chain thereof, operably linked to a heterologous promoter. In preferred embodiments for the expression of double-chained antibodies, vectors encoding both the heavy and light chains may be co-expressed in the host cell for expression of the entire immunoglobuhn molecule, as detailed below. A variety of host-expression vector systems may be utilized to express the antibody molecules of the invention. Such host-expression systems represent vehicles by which the coding sequences of interest may be produced and subsequently purified, but also represent cells which may, when transformed or transfected with the appropriate nucleotide coding sequences, express an antibody molecule of the invention in situ. These include but are not limited to microorganisms such as bacteria (e.g., E. coli, B. subtilis) transformed with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA expression vectors containing antibody coding sequences; yeast (e.g., Saccharomyces, Pichia) transformed with recombinant yeast expression vectors containing antibody coding sequences; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing antibody coding sequences; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing antibody coding sequences; or mammalian cell systems (e.g., COS, CHO, BHK, 293, 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K promoter). Preferably, bacterial cells such as Escherichia coli, and more preferably, eukaryotic cells, especially for the expression of whole recombinant antibody molecule, are used for the expression of a recombinant antibody molecule. For example, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for antibodies (Foecking et al., 1986, Gene 45:101; Cockett et al., 1990, Bio Technology 8:2). In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the antibody molecule being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of pharmaceutical compositions of an antibody molecule, vectors which direct the expression of high levels of fusion protein products that are readily purified may be desirable. Such vectors include, but are not limited, to the E. coli expression vector pUR278 (Ruther et al., 1983, EMBO J. 2: 1791), in which the antibody coding sequence may be ligated individually into the vector in frame with the lac Z coding region so that a fusion protein is produced; pIN vectors (Inouye & Inouye, 1985, Nucleic Acids Res. 13:3101-3109; Van Heeke & Schuster, 1989, J. Biol. Chem. 24:5503-5509); and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione S-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsoφtion and binding to a matrix glutathione-agarose beads followed by elution in the presence of free glutathione. The pGEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety. In an insect system, Autographa californica nuclear polyhedrosis virus (AcNPV) is used as a vector to express foreign genes. The virus grows in Spodoptera frugiperda cells. The antibody coding sequence may be cloned individually into non- essential regions (for example the polyhedrin gene) of the virus and placed under control of an AcNPV promoter (for example the polyhedrin promoter). In mammalian host cells, a number of viral-based expression systems may be utilized. In cases where an adenovirus is used as an expression vector, the antibody coding sequence of interest may be ligated to an adenovirus transcription/translation control complex, e.g., the late promoter and tripartite leader sequence. This chimeric gene may then be inserted in the adenovirus genome by in vitro or in vivo recombination. Insertion in a non- essential region of the viral genome (e.g., region El or E3) will result in a recombinant virus that is viable and capable of expressing the antibody molecule in infected hosts, (e.g., see Logan & Shenk, 1984, Proc. Natl. Acad. Sci. USA 81:355-359). Specific initiation signals may also be required for efficient translation of inserted antibody coding sequences. These signals include the ATG initiation codon and adjacent sequences. Furthermore, the initiation codon must be in phase with the reading frame of the desired coding sequence to ensure translation of the entire insert. These exogenous translational control signals and initiation codons can be of a variety of origins, both natural and synthetic. The efficiency of expression may be enhanced by the inclusion of appropriate transcription enhancer elements, transcription terminators, etc. (see Bittner et al., 1987, Methods in Enzymol. 153:51-544). In addition, a host cell strain may be chosen which modulates the expression of the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post- translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the coπect modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. Such mammalian host cells include but are not limited to CHO, VERY, BHK, Hela, COS, MDCK, 293, 3T3, WI38, and in particular, breast cancer cell lines such as, for example, BT483, Hs578T, HTB2, BT20 and T47D, and normal mammary gland cell line such as, for example, CRL7030 and Hs578Bst. For long-term, high-yield production of recombinant proteins, stable expression is preferred. For example, cell lines which stably express the antibody molecule may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines. This method may advantageously be used to engineer cell lines which express the antibody molecule. Such engineered cell lines may be particularly useful in screening and evaluation of compounds that interact directly or indirectly with the antibody molecule. A number of selection systems may be used, including but not limited to the heφes simplex virus thymidine kinase (Wigler et al., 1977, Cell 11:223), hypoxanthine-guanine phosphoribosyltransferase (Szybalska & Szybalski, 192, Proc. Natl. Acad. Sci. USA 48:202), and adenine phosphoribosyltransferase (Lowy et al., 1980, Cell 22:817) genes can be employed in tk-, hgprt- or aprt- cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler et al., 1980, Natl. Acad. Sci. USA 77:357; O'Hare et al., 1981, Proc. Natl. Acad. Sci. USA 78:1527); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, 1981, Proc. Natl. Acad. Sci. USA 78:2072); neo, which confers resistance to the aminoglycoside G-418 Clinical Pharmacy 12:488-505; Wu and Wu, 1991, Biotherapy 3:87-95; Tolstoshev, 1993, Ann. Rev. Pharmacol. Toxicol. 32:573-596; Mulligan, 1993, Science 260:926- 932; and Morgan and Anderson, 1993, Ann. Rev. Biochem. 62: 191-217; May, 1993, TIB TECH 11(5):155-215); and hygro, which confers resistance to hygromycin (Santerre et al., 1984, Gene 30: 147). Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et al. (eds.), 1993, Current Protocols in Molecular Biology, John Wiley & Sons, NY; Kriegler, 1990, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY; and in Chapters 12 and 13, Dracopoli et al. (eds), 1994, Current Protocols in Human Genetics, John Wiley & Sons, NY.; Colberre-Garapin et al., 1981, J. Mol. Biol. 150: 1, which are incoφorated by reference herein in their entireties. The expression levels of an antibody molecule can be increased by vector amplification (for a review, see Bebbington and Hentschel, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, Vol.3. (Academic Press, New York, 1987)). When a marker in the vector system expressing antibody is amplifiable, increase in the level of inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the antibody gene, production of the antibody will also increase (Crouse et al., 1983, Mol. Cell. Biol. 3:257). The host cell may be co-transfected with two expression vectors of the invention, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors may contain identical selectable markers which enable equal expression of heavy and light chain polypeptides. Alternatively, a single vector may be used which encodes both heavy and light chain polypeptides. In such situations, the light chain should be placed before the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, 1986, Nature 322:52; Kohler, 1980, Proc. Natl. Acad. Sci. USA 77:2197). The coding sequences for the heavy and light chains may comprise cDNA or genomic DNA. Once an antibody molecule of the invention has been recombinantly expressed, it may be purified by any method known in the art for purification of an immunoglobuhn molecule, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Antibody conjugates. The present invention encompasses antibodies recombinantly fused or chemically conjugated (including both covalently and non-covalently conjugations) to a polypeptide (or portion thereof, preferably at least 10, 20 or 50 amino acids of the polypeptide) of the present invention to generate fusion proteins. The fusion does not necessarily need to be direct, but may occur through linker sequences. The antibodies may be specific for antigens other than polypeptides (or portion thereof, preferably at least 10, 20 or 50 amino acids of the polypeptide) of the present invention. For example, antibodies may be used to target the polypeptides of the present invention to particular cell types, either in vitro or in vivo, by fusing or conjugating the polypeptides of the present invention to antibodies specific for particular cell surface receptors. Antibodies fused or conjugated to the polypeptides of the present invention may also be used in in vitro immunoassays and purification methods using methods known in the art. See e.g., Harbor et al., supra, and PCT publication WO 93/21232; EP 439,095; Naramura et al., Immunol. Lett. 39:91-99 (1994); U.S. Patent 5,474,981; Gillies et al., PNAS 89:1428-1432 (1992); Fell et al., J. Immunol. 146:2446- 2452(1991), which are incoφorated by reference in their entireties. The present invention further includes compositions comprising the polypeptides of the present invention fused or conjugated to antibody domains other than the variable regions. For example, the polypeptides of the present invention may be fused or conjugated to an antibody Fc region, or portion thereof. The antibody portion fused to a polypeptide of the present invention may comprise the constant region, hinge region, CHI domain, CH2 domain, and CH3 domain or any combination of whole domains or portions thereof. The polypeptides may also be fused or conjugated to the above antibody portions to form multimers. For example, Fc portions fused to the polypeptides of the present invention can form dimers through disulfide bonding between the Fc portions. Higher multimeric forms can be made by fusing the polypeptides to portions of IgA and IgM. Methods for fusing or conjugating the polypeptides of the present invention to antibody portions are known in the art. See, e.g., U.S. Patent Nos. 5,336,603; 5,622,929; 5,359,046; 5,349,053; 5,447,851; 5,112,946; EP 307,434; EP 367,166; PCT publications WO 96/04388; WO 91/06570; Ashkenazi et al., Proc. Natl. Acad. Sci. USA 88: 10535-10539 (1991); Zheng et al., J. Immunol. 154:5590-5600 (1995); and Vil et al., Proc. Natl. Acad. Sci. USA 89: 11337- 11341(1992) (said references incoφorated by reference in their entireties). As discussed, supra, the polypeptides of the present invention may be fused or conjugated to the above antibody portions to increase the in vivo half life of the polypeptides or for use in immunoassays using methods known in the art. Further, the polypeptides of the present invention may be fused or conjugated to the above antibody portions to facilitate purification. One reported example describes chimeric proteins consisting of the first two domains of the human CD4-polypeptide and various domains of the constant regions of the heavy or light chains of mammalian immunoglobulins. (EP 394,827; Traunecker et al., Nature 331:84-86 (1988). The polypeptides of the present invention fused or conjugated to an antibody having disulfide- linked dimeric structures (due to the IgG) may also be more efficient in binding and neutralizing other molecules, than the monomeric secreted protein or protein fragment alone. (Fountoulakis et al., J. Biochem. 270:3958-3964 (1995)). In many cases, the Fc part in a fusion protein is beneficial in therapy and diagnosis, and thus can result in, for example, improved pharmacokinetic properties. (EP A 232,262). Alternatively, deleting the Fc part after the fusion protein has been expressed, detected, and purified, would be desired. For example, the Fc portion may hinder therapy and diagnosis if the fusion protein is used as an antigen for immunizations. In drug discovery, for example, human proteins, such as hIL-5, have been fused with Fc portions for the puφose of high-throughput screening assays to identify antagonists of hIL-5. (See, D. Bennett et al., J. Molecular Recognition 8:52- 58 (1995); K. Johanson et al., J. Biol. Chem. 270:9459-9471 (1995)0. Moreover, the antibodies or fragments thereof of the present invention can be fused to marker sequences, such as a peptide to facilitates their purification. In preferred embodiments, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, CA, 91311), among others, many of which are commercially available. As described in Gentz et al., Proc. Natl. Acad. Sci. USA 86:821-824 (1989), for instance, hexa-histidine provides for convenient purification of the fusion protein. Other peptide tags useful for purification include, but are not limited to, the "HA" tag, which coπesponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., Cell 37:767 (1984)) and the "flag" tag. The present invention further encompasses antibodies or fragments thereof conjugated to a diagnostic or therapeutic agent. The antibodies can be used diagnostically to, for example, monitor the development or progression of a tumor as part of a clinical testing procedure to, e.g., determine the efficacy of a given treatment regimen. Detection can be facilitated by coupling the antibody to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, radioactive materials, positron emitting metals using various positron emission tomographies, and nonradioactive paramagnetic metal ions. See, for example, U.S. Patent No. 4,741,900 for metal ions which can be conjugated to antibodies for use as diagnostics according to the present invention. Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin; examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; an example of a luminescent material includes luminol; examples of bioluminescent materials include luciferase, luciferin, and aequorin; and examples of suitable radioactive material include 1251, 1311, l l lln or 99Tc. Further, an antibody or fragment thereof may be conjugated to a therapeutic moiety such as a cytotoxin, e.g., a cytostatic or cytocidal agent, a therapeutic agent or a radioactive metal ion. A cytotoxin or cytotoxic agent includes any agent that is detrimental to cells. Examples include paclitaxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cis- dichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents (e.g., vincristine and vinblastine). The conjugates of the invention can be used for modifying a given biological response, the therapeutic agent or drug moiety is not to be construed as limited to classical chemical therapeutic agents. For example, the drug moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin, or diphtheria toxin; a protein such as tumor necrosis factor, a-interferon, β-interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator, a thrombotic agent or an anti- angiogenic agent, e.g., angiostatin or endostatin; or, biological response modifiers such as, for example, lymphokines, interleukin-1 ("IL-1"), interleukin-2 ("IL-2"), interleukin-6 ("IL-6"), granulocyte macrophase colony stimulating factor ("GM- CSF"), granulocyte colony stimulating factor ("G-CSF"), or other growth factors. Antibodies may also be attached to solid supports, which are particularly useful for immunoassays or purification of the target antigen. Such solid supports include, but are not limited to, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene. Techniques for conjugating such therapeutic moiety to antibodies are well known, see, e.g., Arnon et al., "Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy", in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss, Inc. 1985); Hellstrom et al., "Antibodies For Drug Delivery", in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53 (Marcel Dekker, Inc. 1987); Thoφe, "Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review", in Monoclonal Antibodies '84: Biological And Clinical Applications, Pinchera et al. (eds.), pp. 475-506 (1985); "Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy", in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), pp. 303-16 (Academic Press 1985), and Thoφe et al., "The Preparation And Cytotoxic Properties Of Antibody-Toxin Conjugates", Immunol. Rev. 62:119-58 (1982). Alternatively, an antibody can be conjugated to a second antibody to form an antibody heteroconjugate as described by Segal in U.S. Patent No. 4,676,980, which is incoφorated herein by reference in its entirety. An antibody, with or without a therapeutic moiety conjugated to it, administered alone or in combination with cytotoxic factor(s) and/or cytokine(s) can be used as a therapeutic. Assays For Antibody Binding The antibodies of the invention may be assayed for immunospecific binding by any method known in the art. The immunoassays which can be used include but are not limited to competitive and non-competitive assay systems using techniques such as western blots, radioimmunoassays, ELISA (enzyme linked immunosorbent assay), "sandwich" immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays, protein A immunoassays, to name but a few. Such assays are routine and well known in the art (see, e.g., Ausubel et al, eds, 1994, Current Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York, which is incoφorated by reference herein in its entirety). Exemplary immunoassays are described briefly below (but are not intended by way of limitation). Immunoprecipitation protocols generally comprise lysing a population of cells in a lysis buffer such as RIPA buffer ( 1 % NP-40 or Triton X- 100, 1 % sodium deoxycholate, 0.1% SDS, 0.15 M NaCl, 0.01 M sodium phosphate at pH 7.2, 1% Trasylol) supplemented with protein phosphatase and/or protease inhibitors (e.g., EDTA, PMSF, aprotinin, sodium vanadate), adding the antibody of interest to the cell lysate, incubating for a period of time (e.g., 1-4 hours) at 4° C, adding protein A and/or protein G sepharose beads to the cell lysate, incubating for about an hour or more at 4° C, washing the beads in lysis buffer and resuspending the beads in SDS/sample buffer. The ability of the antibody of interest to immunoprecipitate a particular antigen can be assessed by, e.g., western blot analysis. One of skill in the art would be knowledgeable as to the parameters that can be modified to increase the binding of the antibody to an antigen and decrease the background (e.g., pre-clearing the cell lysate with sepharose beads). For further discussion regarding immunoprecipitation protocols see, e.g., Ausubel et al, eds, 1994, Cmrent Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York at 10.16.1. Western blot analysis generally comprises preparing protein samples, electrophoresis of the protein samples in a polyacrylamide gel (e.g., 8%- 20% SDS- PAGE depending on the molecular weight of the antigen), transferring the protein sample from the polyacrylamide gel to a membrane such as nitrocellulose, PVDF or nylon, blocking the membrane in blocking solution (e.g., PBS with 3% BSA or non-fat milk), washing the membrane in washing buffer (e.g., PBS-Tween 20), blocking the membrane with primary antibody (the antibody of interest) diluted in blocking buffer, washing the membrane in washing buffer, blocking the membrane with a secondary antibody (which recognizes the primary antibody, e.g., an anti-human antibody) conjugated to an enzymatic substrate (e.g., horseradish peroxidase or alkaline phosphatase) or radioactive molecule (e.g., 32P or 1251) diluted in blocking buffer, washing the membrane in wash buffer, and detecting the presence of the antigen. One of skill in the art would be knowledgeable as to the parameters that can be modified to increase the signal detected and to reduce the background noise. For further discussion regarding western blot protocols see, e.g., Ausubel et al, eds, 1994, Cuπent Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York at 10.8.1. ELISAs comprise preparing antigen, coating the well of a 96 well microtiter plate with the antigen, adding the antibody of interest conjugated to a detectable compound such as an enzymatic substrate (e.g., horseradish peroxidase or alkaline phosphatase) to the well and incubating for a period of time, and detecting the presence of the antigen. In ELISAs the antibody of interest does not have to be conjugated to a detectable compound; instead, a second antibody (which recognizes the antibody of interest) conjugated to a detectable compound may be added to the well. Further, instead of coating the well with the antigen, the antibody may be coated to the well. In this case, a second antibody conjugated to a detectable compound may be added following the addition of the antigen of interest to the coated well. One of skill in the art would be knowledgeable as to the parameters that can be modified to increase the signal detected as well as other variations of ELISAs known in the art. For further discussion regarding ELISAs see, e.g., Ausubel et al, eds, 1994, Current Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York at 11.2.1. The binding affinity of an antibody to an antigen and the off-rate of an antibody-antigen interaction can be determined by competitive binding assays. One example of a competitive binding assay is a radioimmunoassay comprising the incubation of labeled antigen (e.g., 3H or 1251) with the antibody of interest in the presence of increasing amounts of unlabeled antigen, and the detection of the antibody bound to the labeled antigen. The affinity of the antibody of interest for a particular antigen and the binding off-rates can be determined from the data by scatchard plot analysis. Competition with a second antibody can also be determined using radioimmunoassays. In this case, the antigen is incubated with antibody of interest is conjugated to a labeled compound (e.g., 3H or 1251) in the presence of increasing amounts of an unlabeled second antibody. Therapeutic Uses. The present invention is further directed to antibody-based therapies which involve administering antibodies of the invention to an animal, preferably a mammal, and most preferably a human, patient for treating one or more of the described disorders. Therapeutic compounds of the invention include, but are not limited to, antibodies of the invention (including fragments, analogs and derivatives thereof as described herein) and nucleic acids encoding antibodies of the invention (including fragments, analogs and derivatives thereof as described herein). The antibodies of the invention can be used to treat, inhibit or prevent diseases and disorders associated with aberrant expression and/or activity of a polypeptide of the invention, including, but not limited to, [insert diseases and disorders]. The treatment and/or prevention of diseases and disorders associated with aberrant expression and/or activity of a polypeptide of the invention includes, but is not limited to, alleviating symptoms associated with those diseases and disorders. Antibodies of the invention may be provided in pharmaceutically acceptable compositions as known in the art or as described herein. A summary of the ways in which the antibodies of the present invention may be used therapeutically includes binding polynucleotides or polypeptides of the present invention locally or systemically in the body or by direct cytotoxicity of the antibody, e.g. as mediated by complement (CDC) or by effector cells (ADCC). Some of these approaches are described in more detail below. Armed with the teachings provided herein, one of ordinary skill in the art will know how to use the antibodies of the present invention for diagnostic, monitoring or therapeutic puφoses without undue experimentation. The antibodies of this invention may be advantageously utilized in combination with other monoclonal or chimeric antibodies, or with lymphokines or hematopoietic growth factors (such as, e.g., IL-2, IL-3 and IL-7), for example, which serve to increase the number or activity of effector cells which interact with the antibodies. The antibodies of the invention may be administered alone or in combination with other types of treatments (e.g., radiation therapy, chemotherapy, hormonal therapy, immunotherapy and anti-tumor agents). Generally, administration of products of a species origin or species reactivity (in the case of antibodies) that is the same species as that of the patient is prefeπed. Thus, in a preferred embodiment, human antibodies, fragments derivatives, analogs, or nucleic acids, are administered to a human patient for therapy or prophylaxis. It is prefeπed to use high affinity and/or potent in vivo inhibiting and/or neutralizing antibodies against polypeptides or polynucleotides of the present invention, fragments or regions thereof, for both immunoassays directed to and therapy of disorders related to polynucleotides or polypeptides, including fragments thereof, of the present invention. Such antibodies, fragments, or regions, will preferably have an affinity for polynucleotides or polypeptides, including fragments thereof. Preferred binding affinities include those with a dissociation constant or Kd less than 5X10 "2 M, 10 "2 M, 5X10 '3 M, 10 "3 M, 5X10 '4 M, 10 "4 M, 5X10 "5 M, 10 "5 M, 5X10 " 6 M, 10 "6 M, 5X10 "7 M, 10 "7 M, 5X10 '8 M, 10 "8 M, 5X10 "9 M, 10 "9 M, 5X10 '°M, 10 ,0 M, 5X10 'π M, 10-"M, 5X10 12 M, 10 12 M, 5X10 I M, 10 13 M, 5X10 ,4 M, 10 14 M, 5X10 15 M, and 10 15 M. Gene Therapy. In a specific embodiment, nucleic acids comprising sequences encoding antibodies or functional derivatives thereof, are administered to treat, inhibit or prevent a disease or disorder associated with abeπant expression and/or activity of a polypeptide of the invention, by way of gene therapy. Gene therapy refers to therapy performed by the administration to a subject of an expressed or expressible nucleic acid. In this embodiment of the invention, the nucleic acids produce their encoded protein that mediates a therapeutic effect. Any of the methods for gene therapy available in the art can be used according to the present invention. Exemplary methods are described below. For general reviews of the methods of gene therapy, see Goldspiel et al., 1993, Clinical Pharmacy 12:488-505; Wu and Wu, 1991, Biotherapy 3:87-95; Tolstoshev, 1993, Ann. Rev. Pharmacol. Toxicol. 32:573-596; Mulligan, 1993, Science 260:926- 932; and Morgan and Anderson, 1993, Ann. Rev. Biochem. 62: 191-217; May, 1993, TIBTECH 11 (5): 155-215). Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et al. (eds.), 1993, Current Protocols in Molecular Biology, John Wiley & Sons, NY; and Kriegler, 1990, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY. In a prefeπed aspect, the compound comprises nucleic acid sequences encoding an antibody, said nucleic acid sequences being part of expression vectors that express the antibody or fragments or chimeric proteins or heavy or light chains thereof in a suitable host. In particular, such nucleic acid sequences have promoters operably linked to the antibody coding region, said promoter being inducible or constitutive, and, optionally, tissue- specific. In another particular embodiment, nucleic acid molecules are used in which the antibody coding sequences and any other desired sequences are flanked by regions that promote homologous recombination at a desired site in the genome, thus providing for intrachromosomal expression of the antibody nucleic acids (Koller and Smithies, 1989, Proc. Natl. Acad. Sci. USA 86:8932-8935; Zijlstra et al., 1989, Nature 342:435-438). In specific embodiments, the expressed antibody molecule is a single chain antibody; alternatively, the nucleic acid sequences include sequences encoding both the heavy and light chains, or fragments thereof, of the antibody. Delivery of the nucleic acids into a patient may be either direct, in which case the patient is directly exposed to the nucleic acid or nucleic acid- carrying vectors, or indirect, in which case, cells are first transformed with the nucleic acids in vitro, then transplanted into the patient. These two approaches are known, respectively, as in vivo or ex vivo gene therapy. In a specific embodiment, the nucleic acid sequences are directly administered in vivo, where it is expressed to produce the encoded product. This can be accomplished by any of numerous methods known in the art, e.g., by constructing them as part of an appropriate nucleic acid expression vector and administering it so that they become intracellular, e.g., by infection using defective or attenuated retrovirals or other viral vectors (see U.S. Patent No. 4,980,286), or by direct injection of naked DNA, or by use of microparticle bombardment (e.g., a gene gun; Biolistic, Dupont), or coating with lipids or cell-surface receptors or transfecting agents, encapsulation in liposomes, microparticles, or microcapsules, or by administering them in linkage to a peptide which is known to enter the nucleus, by administering it in linkage to a ligand subject to receptor-mediated endocytosis (see, e.g., Wu and Wu, 1987, J. Biol. Chem. 262:4429-4432) (which can be used to target cell types specifically expressing the receptors), etc. In another embodiment, nucleic acid- ligand complexes can be formed in which the ligand comprises a fusogenic viral peptide to disrupt endosomes, allowing the nucleic acid to avoid lysosomal degradation. In yet another embodiment, the nucleic acid can be targeted in vivo for cell specific uptake and expression, by targeting a specific receptor (see, e.g., PCT Publications WO 92/06180 dated April 16, 1992 (Wu et al.); WO 92/22635 dated December 23, 1992 (Wilson et al.); WO92/20316 dated November 26, 1992 (Findeis et al.); WO93/14188 dated July 22, 1993 (Clarke et al.), WO 93/20221 dated October 14, 1993 (Young)). Alternatively, the nucleic acid can be introduced intracellularly and incoφorated within host cell DNA for expression, by homologous recombination (Koller and Smithies, 1989, Proc. Natl. Acad. Sci. USA 86:8932-8935; Zijlstra et al., 1989, Nature 342:435-438). In a specific embodiment, viral vectors that contains nucleic acid sequences encoding an antibody of the invention are used. For example, a retroviral vector can be used (see Miller et al., 1993, Meth. Enzymol. 217:581-599). These retroviral vectors have been to delete retroviral sequences that are not necessary for packaging of the viral genome and integration into host cell DNA. The nucleic acid sequences encoding the antibody to be used in gene therapy are cloned into one or more vectors, which facilitates delivery of the gene into a patient. More detail about retroviral vectors can be found in Boesen et al., 1994, Biotherapy 6:291-302, which describes the use of a retroviral vector to deliver the mdrl gene to hematopoietic stem cells in order to make the stem cells more resistant to chemotherapy. Other references illustrating the use of retroviral vectors in gene therapy are: Clowes et al., 1994, J. Clin. Invest. 93:644-651; Kiem et al., 1994, Blood 83:1467-1473; Salmons and Gunzberg, 1993, Human Gene Therapy 4:129-141; and Grossman and Wilson, 1993, Cuπ. Opin. in Genetics and Devel. 3:110-114. Adenoviruses are other viral vectors that can be used in gene therapy. Adenoviruses are especially attractive vehicles for delivering genes to respiratory epithelia. Adenoviruses naturally infect respiratory epithelia where they cause a mild disease. Other targets for adenovirus-based delivery systems are liver, the central nervous system, endothelial cells, and muscle. Adenoviruses have the advantage of being capable of infecting non-dividing cells. Kozarsky and Wilson, 1993, Current Opinion in Genetics and Development 3:499-503 present a review of adenovirus- based gene therapy. Bout et al., 1994, Human Gene Therapy 5:3-10 demonstrated the use of adenovirus vectors to transfer genes to the respiratory epithelia of rhesus monkeys. Other instances of the use of adenoviruses in gene therapy can be found in Rosenfeld et al., 1991, Science 252:431-434; Rosenfeld et al., 1992, Cell 68: 143- 155; Mastrangeli et al., 1993, J. Clin. Invest. 91:225-234; PCT Publication WO94/12649; and Wang, et al., 1995, Gene Therapy 2:775-783. In a prefeπed embodiment, adenovirus vectors are used. Adeno-associated virus (AAV) has also been proposed for use in gene therapy (Walsh et al., 1993, Proc. Soc. Exp. Biol. Med. 204:289-300; U.S. Patent No. 5,436,146). Another approach to gene therapy involves transfeπing a gene to cells in tissue culture by such methods as electroporation, lipofection, calcium phosphate mediated transfection, or viral infection. Usually, the method of transfer includes the transfer of a selectable marker to the cells. The cells are then placed under selection to isolate those cells that have taken up and are expressing the transfeπed gene. Those cells are then delivered to a patient. In this embodiment, the nucleic acid is introduced into a cell prior to administration in vivo of the resulting recombinant cell. Such introduction can be caπied out by any method known in the art, including but not limited to transfection, electroporation, microinjection, infection with a viral or bacteriophage vector containing the nucleic acid sequences, cell fusion, chromosome-mediated gene transfer, microcell-mediated gene transfer, spheroplast fusion, etc. Numerous techniques are known in the art for the introduction of foreign genes into cells (see, e.g., Loeffler and Behr, 1993, Meth. Enzymol. 217:599-618; Cohen et al., 1993, Meth. Enzymol. 217:618-644; Cline, 1985, Pharmac. Ther. 29:69-92) and may be used in accordance with the present invention, provided that the necessary developmental and physiological functions of the recipient cells are not disrupted. The technique should provide for the stable transfer of the nucleic acid to the cell, so that the nucleic acid is expressible by the cell and preferably heritable and expressible by its cell progeny. The resulting recombinant cells can be delivered to a patient by various methods known in the art. Recombinant blood cells (e.g., hematopoietic stem or progenitor cells) are preferably administered intravenously. The amount of cells envisioned for use depends on the desired effect, patient state, etc., and can be determined by one skilled in the art. Cells into which a nucleic acid can be introduced for puφoses of gene therapy encompass any desired, available cell type, and include but are not limited to epithelial cells, endothelial cells, keratinocytes, fibroblasts, muscle cells, hepatocytes; blood cells such as Tlymphocytes, Blymphocytes, monocytes, macrophages, neutrophils, eosinophils, megakaryocytes, granulocytes; various stem or progenitor cells, in particular hematopoietic stem or progenitor cells, e.g., as obtained from bone marrow, umbilical cord blood, peripheral blood, fetal liver, etc. In a prefeπed embodiment, the cell used for gene therapy is autologous to the patient. In an embodiment in which recombinant cells are used in gene therapy, nucleic acid sequences encoding an antibody are introduced into the cells such that they are expressible by the cells or their progeny, and the recombinant cells are then administered in vivo for therapeutic effect. In a specific embodiment, stem or progenitor cells are used. Any stem and/or progenitor cells which can be isolated and maintained in vitro can potentially be used in accordance with this embodiment of the present invention (see e.g. PCT Publication WO 94/08598, dated April 28, 1994; Stemple and Anderson, 1992, Cell 71:973-985; Rheinwald, 1980, Meth. Cell Bio. 21A:229; and Pittelkow and Scott, 1986, Mayo Clinic Proc. 61:771). In a specific embodiment, the nucleic acid to be introduced for puφoses of gene therapy comprises an inducible promoter operably linked to the coding region, such that expression of the nucleic acid is controllable by controlling the presence or absence of the appropriate inducer of transcription. Demonstration of Therapeutic or Prophylactic Activity. The compounds or pharmaceutical compositions of the invention are preferably tested in vitro, and then in vivo for the desired therapeutic or prophylactic activity, prior to use in humans. For example, in vitro assays to demonstrate the therapeutic or prophylactic utility of a compound or pharmaceutical composition include, the effect of a compound on a cell line or a patient tissue sample. The effect of the compound or composition on the cell line and/or tissue sample can be determined utilizing < techniques known to those of skill in the art including, but not limited to, rosette formation assays and cell lysis assays. In accordance with the invention, in vitro assays which can be used to determine whether administration of a specific compound is indicated, include in vitro cell culture assays in which a patient tissue sample is grown in culture, and exposed to or otherwise administered a compound, and the effect of such compound upon the tissue sample is observed. Therapeutic/Prophylactic Administration and Composition. The invention provides methods of treatment, inhibition and prophylaxis by administration to a subject of an effective amount of a compound or pharmaceutical composition of the invention, preferably an antibody of the invention. In a prefeπed aspect, the compound is substantially purified (e.g., substantially free from substances that limit its effect or produce undesired side-effects). The subject is preferably an animal, including but not limited to animals such as cows, pigs, horses, chickens, cats, dogs, etc., and is preferably a mammal, and most preferably human. Formulations and methods of administration that can be employed when the compound comprises a nucleic acid or an immunoglobuhn are described above; additional appropriate formulations and routes of administration can be selected from among those described herein below. Various delivery systems are known and can be used to administer a compound of the invention, e.g., encapsulation in liposomes, microparticles, microcapsules, recombinant cells capable of expressing the compound, receptor-mediated endocytosis (see, e.g., Wu and Wu, 1987, J. Biol. Chem. 262:4429-4432), construction of a nucleic acid as part of a retroviral or other vector, etc. Methods of introduction include but are not limited to intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal, epidural, and oral routes. The compounds or compositions may be administered by any convenient route, for example by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, rectal and intestinal mucosa, etc.) and may be administered together with other biologically active agents. Administration can be systemic or local. In addition, it may be desirable to introduce the pharmaceutical compounds or compositions of the invention into the central nervous system by any suitable route, including intraventricular and intrathecal injection; intraventricular injection may be facilitated by an intraventricular catheter, for example, attached to a reservoir, such as an Ommaya reservoir. Pulmonary administration can also be employed, e.g., by use of an inhaler or nebulizer, and formulation with an aerosolizing agent. In a specific embodiment, it may be desirable to administer the pharmaceutical compounds or compositions of the invention locally to the area in need of treatment; this may be achieved by, for example, and not by way of limitation, local infusion during surgery, topical application, e.g., in conjunction with a wound dressing after surgery, by injection, by means of a catheter, by means of a suppository, or by means of an implant, said implant being of a porous, non-porous, or gelatinous material, including membranes, such as sialastic membranes, or fibers. Preferably, when administering a protein, including an antibody, of the invention, care must be taken to use materials to which the protein does not absorb. In another embodiment, the compound or composition can be delivered in a vesicle, in particular a liposome (see Langer, 1990, Science 249:1527-1533; Treat et al., in Liposomes in the Therapy of Infectious Disease and Cancer, Lopez-Berestein and Fidler (eds.), Liss, New York, pp. 353- 365 (1989); Lopez-Berestein, ibid., pp. 317-327; see generally ibid.) In yet another embodiment, the compound or composition can be delivered in a controlled release system. In one embodiment, a pump may be used (see Langer, supra; Sefton, 1987, CRC Crit. Ref. Biomed. Eng. 14:201; Buchwald et al., 1980, Surgery 88:507; Saudek et al., 1989, N. Engl. J. Med. 321:574). In another embodiment, polymeric materials can be used (see Medical Applications of Controlled Release, Langer and Wise (eds.), CRC Pres., Boca Raton, Florida (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley, New York (1984); Ranger and Peppas, J., 1983, Macromol. Sci. Rev. Macromol. Chem. 23:61; see also Levy et al., 1985, Science 228: 190; During et al., 1989, Ann. Neurol. 25:351; Howard et al., 1989, J.Neurosurg. 71: 105). In yet another embodiment, a controlled release system can be placed in proximity of the therapeutic target, i.e., the brain, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138 (1984)). Other controlled release systems are discussed in the review by Langer (1990, Science 249: 1527-1533). In a specific embodiment where the compound of the invention is a nucleic acid encoding a protein, the nucleic acid can be administered in vivo to promote expression of its encoded protein, by constructing it as part of an appropriate nucleic acid expression vector and administering it so that it becomes intracellular, e.g., by use of a retroviral vector (see U.S. Patent No. 4,980,286), or by direct injection, or by use of microparticle bombardment (e.g., a gene gun; Biolistic, Dupont), or coating with lipids or cell-surface receptors or transfecting agents, or by administering it in linkage to a homeobox- like peptide which is known to enter the nucleus (see e.g., Joliot et al, 1991, Proc. Natl. Acad. Sci. USA 88:1864-1868), etc. Alternatively, a nucleic acid can be introduced intracellularly and incorporated within host cell DNA for expression, by homologous recombination. The present invention also provides pharmaceutical compositions. Such compositions comprise a therapeutically effective amount of a compound, and a pharmaceutically acceptable caπier. In a specific embodiment, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term "caπier" refers to a diluent, adjuvant, excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical caπiers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a prefeπed caπier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid caπiers, particularly for injectable solutions. Suitable pharmaceutical excipients include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The composition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. These compositions can take the form of solutions, suspensions, emulsion, tablets, pills, capsules, powders, sustained-release formulations and the like. The composition can be formulated as a suppository, with traditional binders and caπiers such as triglycerides. Oral formulation can include standard carriers such as pharmaceutical grades of mannitol, lactose, starch, magnesium stearate, sodium saccharine, cellulose, magnesium carbonate, etc. Examples of suitable pharmaceutical earners are described in "Remington's Pharmaceutical Sciences" by E.W. Martin. Such compositions will contain a therapeutically effective amount of the compound, preferably in purified form, together with a suitable amount of carrier so as to provide the form for proper administration to the patient. The formulation should suit the mode of administration. In a prefeπed embodiment, the composition is formulated in accordance with routine procedures as a pharmaceutical composition adapted for intravenous administration to human beings. Typically, compositions for intravenous administration are solutions in sterile isotonic aqueous buffer. Where necessary, the composition may also include a solubilizing agent and a local anesthetic such as lignocaine to ease pain at the site of the injection. Generally, the ingredients are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the composition is to be administered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the composition is administered by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients may be mixed prior to administration. The compounds of the invention can be formulated as neutral or salt forms. Pharmaceutically acceptable salts include those formed with anions such as those derived from hydrochloric, phosphoric, acetic, oxalic, tartaric acids, etc., and those formed with cations such as those derived from sodium, potassium, ammonium, calcium, ferric hydroxides, isopropylamine, triethylamine, 2-ethylamino ethanol, histidine, procaine, etc. The amount of the compound of the invention which will be effective in the treatment, inhibition and prevention of a disease or disorder associated with abeπant expression and/or activity of a polypeptide of the invention can be determined by standard clinical techniques. In addition, in vitro assays may optionally be employed to help identify optimal dosage ranges. The precise dose to be employed in the formulation will also depend on the route of administration, and the seriousness of the disease or disorder, and should be decided according to the judgment of the practitioner and each patient's circumstances. Effective doses may be extrapolated from dose-response curves derived from in vitro or animal model test systems. For antibodies, the dosage administered to a patient is typically 0.1 mg/kg to 100 mg/kg of the patient's body weight. Preferably, the dosage administered to a patient is between 0.1 mg/kg and 20 mg/kg of the patient's body weight, more preferably 1 mg/kg to 10 mg/kg of the patient's body weight. Generally, human antibodies have a longer half-life within the human body than antibodies from other species due to the immune response to the foreign polypeptides. Thus, lower dosages of human antibodies and less frequent administration is often possible. Further, the dosage and frequency of administration of antibodies of the invention may be reduced by enhancing uptake and tissue penetration (e.g., into the brain) of the antibodies by modifications such as, for example, lipidation. The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. Diagnosis and Imaging Labeled antibodies, and derivatives and analogs thereof, which specifically bind to a polypeptide of interest can be used for diagnostic puφoses to detect, diagnose, or monitor diseases and/or disorders associated with the abeπant expression and/or activity of a polypeptide of the invention. The invention provides for the detection of aberrant expression of a polypeptide of interest, comprising (a) assaying the expression of the polypeptide of interest in cells or body fluid of an individual using one or more antibodies specific to the polypeptide interest and (b) comparing the level of gene expression with a standard gene expression level, whereby an increase or decrease in the assayed polypeptide gene expression level compared to the standard expression level is indicative of abeπant expression. The invention provides a diagnostic assay for diagnosising a disorder, comprising (a) assaying the expression of the polypeptide of interest in cells or body fluid of an individual using one or more antibodies specific to the polypeptide interest and (b) comparing the level of gene expression with a standard gene expression level, whereby an increase or decrease in the assayed polypeptide gene expression level compared to the standard expression level is indicative of a particular disorder. With respect to cancer, the presence of a relatively high amount of transcript 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 allow health professionals to employ preventative measures or aggressive treatment earlier thereby preventing the development or further progression of the cancer. Antibodies of the invention can be used to assay protein levels in a biological sample using classical immunohistological methods known to those of skill in the art (e.g., see Jalkanen, M., et al., J. Cell. Biol. 101:976-985 (1985); Jalkanen, M., et al., J. Cell . Biol. 105:3087-3096 (1987)). Other antibody-based methods useful for detecting protein gene expression include immunoassays, such as the enzyme linked immunosorbent assay (ELISA) and the radioimmunoassay (RIA). Suitable antibody assay labels are known in the art and include enzyme labels, such as, glucose oxidase; radioisotopes, such as.iodine (1251, 1211), carbon (14C), sulfur (35S), tritium (3H), indium (112In), and technetium (99Tc); luminescent labels, such as luminol; and fluorescent labels, such as fluorescein and rhodamine, and biotin. One aspect of the invention is the detection and diagnosis of a disease or disorder associated with aberrant expression of a polypeptide of the interest in an animal, preferably a mammal and most preferably a human. In one embodiment, diagnosis comprises: a) administering (for example, parenterally, subcutaneously, or intraperitoneally) to a subject an effective amount of a labeled molecule which specifically binds to the polypeptide of interest; b) waiting for a time interval following the administering for permitting the labeled molecule to preferentially concentrate at sites in the subject where the polypeptide is expressed (and for unbound labeled molecule to be cleared to background level); c) determining background level; and d) detecting the labeled molecule in the subject, such that detection of labeled molecule above the background level indicates that the subject has a particular disease or disorder associated with aberrant expression of the polypeptide of interest. Background level can be determined by various methods including, comparing the amount of labeled molecule detected to a standard value previously determined for a particular system. It will be understood in the art that the size of the subject and the imaging system used will determine the quantity of imaging moiety needed to produce diagnostic images. In the case of a radioisotope moiety, for a human subject, the quantity of radioactivity injected will normally range from about 5 to 20 millicuries of 99mTc. The labeled antibody or antibody fragment will then preferentially accumulate at the location of cells which contain the specific protein. In vivo tumor imaging is described in S.W. Burchiel et al., "Immunopharmacokinetics of Radiolabeled Antibodies and Their Fragments." (Chapter 13 in Tumor Imaging: The Radiochemical Detection of Cancer, S.W. Burchiel and B. A. Rhodes, eds., Masson Publishing Inc. (1982). Depending on several variables, including the type of label used and the mode of administration, the time interval following the administration for permitting the labeled molecule to preferentially concentrate at sites in the subject and for unbound labeled molecule to be cleared to background level is 6 to 48 hours or 6 to 24 hours or 6 to 12 hours. In another embodiment the time interval following administration is 5 to 20 days or 5 to 10 days. In an embodiment, monitoring of the disease or disorder is caπied out by repeating the method for diagnosing the disease or disease, for example, one month after initial diagnosis, six months after initial diagnosis, one year after initial diagnosis, etc. Presence of the labeled molecule can be detected in the patient using methods known in the art for in vivo scanning. These methods depend upon the type of label used. Skilled artisans will be able to determine the appropriate method for detecting a particular label. Methods and devices that may be used in the diagnostic methods of the invention include, but are not limited to, computed tomography (CT), whole body scan such as position emission tomography (PET), magnetic resonance imaging (MRI), and sonography. In a specific embodiment, the molecule is labeled with a radioisotope and is detected in the patient using a radiation responsive surgical instrument (Thurston et al., U.S. Patent No. 5,441,050). In another embodiment, the molecule is labeled with a fluorescent compound and is detected in the patient using a fluorescence responsive scanning instrument. In another embodiment, the molecule is labeled with a positron emitting metal and is detected in the patent using positron emission-tomography. In yet another embodiment, the molecule is labeled with a paramagnetic label and is detected in a patient using magnetic resonance imaging (MRI). Kits. The present invention provides kits that can be used in the above methods. In one embodiment, a kit comprises an antibody of the invention, preferably a purified antibody, in one or more containers. In a specific embodiment, the kits of the present invention contain a substantially isolated polypeptide comprising an epitope which is specifically immunoreactive with an antibody included in the kit. Preferably, the kits of the present invention further comprise a control antibody which does not react with the polypeptide of interest. In another specific embodiment, the kits of the present invention contain a means for detecting the binding of an antibody to a polypeptide of interest (e.g., the antibody may be conjugated to a detectable substrate such as a fluorescent compound, an enzymatic substrate, a radioactive compound or a luminescent compound, or a second antibody which recognizes the first antibody may be conjugated to a detectable substrate). In another specific embodiment of the present invention, the kit is a diagnostic kit for use in screening serum containing antibodies specific against proliferative and/or cancerous polynucleotides and polypeptides. Such a kit may include a control antibody that does not react with the polypeptide of interest. Such a kit may include a substantially isolated polypeptide antigen comprising an epitope which is specifically immunoreactive with at least one anti-polypeptide antigen antibody. Further, such a kit includes means for detecting the binding of said antibody to the antigen (e.g., the antibody may be conjugated to a fluorescent compound such as fluorescein or rhodamine which can be detected by flow cytometry). In specific embodiments, the kit may include a recombinantly produced or chemically synthesized polypeptide antigen. The polypeptide antigen of the kit may also be attached to a solid support. In a more specific embodiment the detecting means of the above-described kit includes a solid support to which said polypeptide antigen is attached. Such a kit may also include a non-attached reporter-labeled anti-human antibody. In this embodiment, binding of the antibody to the polypeptide antigen can be detected by binding of the said reporter-labeled antibody. In an additional embodiment, the invention includes a diagnostic kit for use in screening serum containing antigens of the polypeptide of the invention. The diagnostic kit includes a substantially isolated antibody specifically immunoreactive with polypeptide or polynucleotide antigens, and means for detecting the binding of the polynucleotide or polypeptide antigen to the antibody. In one embodiment, the antibody is attached to a solid support. In a specific embodiment, the antibody may be a monoclonal antibody. The detecting means of the kit may include a second, labeled monoclonal antibody. Alternatively, or in addition, the detecting means may include a labeled, competing antigen. In one diagnostic configuration, test serum is reacted with a solid phase reagent having a surface-bound antigen obtained by the methods of the present invention. After binding with specific antigen antibody to the reagent and removing unbound serum components by washing, the reagent is reacted with reporter-labeled anti- human antibody to bind reporter to the reagent in proportion to the amount of bound anti-antigen antibody on the solid support. The reagent is again washed to remove unbound labeled antibody, and the amount of reporter associated with the reagent is determined. Typically, the reporter is an enzyme which is detected by incubating the solid phase in the presence of a suitable fluorometric, luminescent or colorimetric substrate (Sigma, St. Louis, MO). The solid surface reagent in the above assay is prepared by known techniques for attaching protein material to solid support material, such as polymeric beads, dip sticks, 96-well plate or filter material. These attachment methods generally include non-specific adsoφtion of the protein to the support or covalent attachment of the protein, typically through a free amine group, to a chemically reactive group on the solid support, such as an activated carboxyl, hydroxyl, or aldehyde group. Alternatively, streptavidin coated plates can be used in conjunction with biotinylated antigen(s). Thus, the invention provides an assay system or kit for caπying out this diagnostic method. The kit generally includes a support with surface- bound recombinant antigens, and a reporter-labeled anti-human antibody for detecting surface-bound anti-antigen antibody. The invention further relates to antibodies which act as agonists or antagonists of the polypeptides of the present invention. For example, the present invention includes antibodies which disrupt the receptor/ligand interactions with the polypeptides of the invention either partially or fully. Included are both receptor- specific antibodies and ligand-specific antibodies. Included are receptor-specific antibodies which do not prevent ligand binding but prevent receptor activation. Receptor activation (i.e., signaling) may be determined by techniques described herein or otherwise known in the art. Also included are receptor-specific antibodies which both prevent ligand binding and receptor activation. Likewise, included are neutralizing antibodies which bind the ligand and prevent binding of the ligand to the receptor, as well as antibodies which bind the ligand, thereby preventing receptor activation, but do not prevent the ligand from binding the receptor. Further included are antibodies which activate the receptor. These antibodies may act as agonists for either all or less than all of the biological activities affected by ligand-mediated receptor activation. The antibodies may be specified as agonists or antagonists for biological activities comprising specific activities disclosed herein. Further included are antibodies that bind to Brainiac-5 iπespective of whether Brainiac-5 is bound to a Brainiac-5 Receptor. These antibodies act as Brainiac-5 agonists as reflected in an increase in cellular proliferation in response to binding of Brainiac-5 to a Brainiac-5 receptor in the presence of these antibodies. The above antibody agonists can be made using methods known in the art. See e.g., WO 96/40281; US Patent 5,811,097; Deng, B. et al., Blood 92(6): 1981-1988 (1998); Chen, Z. et al., Cancer Res. 58(16):3668- 3678 (1998); Haπop, J.A. et al., J. Immunol. 161(4): 1786-1794 (1998); Zhu, Z. et al., Cancer Res. 58(15):3209-3214 (1998); Yoon, D.Y. et al., J. Immunol. 160(7):3170- 3179 (1998); Prat, M. et al., J. Cell. Sci. l l l(Pt2):237-247 (1998); Pitard, V. et al., J. Immunol. Methods 205(2): 177-190 (1997); Liautard, J. et al., Cytokinde 9(4):233-241 (1997); Carlson, N.G. et al., J. Biol. Chem. 272(17): 11295-11301 (1997); Taryman, R.E. et al., Neuron 14(4):755-762 (1995); Muller, Y.A. et al., Structure 6(9):1153- 1167 (1998); Bartunek, P. et al., Cytokine 8(l):14-20 (1996) (said references incoφorated by reference in their entireties). In a specific embodiment, the antibodies of the invention fix complement. In other specific embodiments, as further described herein, the antibodies of the invention (or fragments thereof) are associated with heterologous polypeptides or nucleic acids (e.g. toxins, such as, compounds that bind and activate endogenous cytotoxic effecter systems, and radioisotopes; and cytotoxic prodrugs). As discussed above, antibodies to the Brainiac-5 polypeptides of the invention can, in turn, be utilized to generate anti-idiotype antibodies that "mimic" the Brainiac - 5, using techniques well known to those skilled in the art. (See, e.g., Greenspan & Bona, FASEB J. 7(5):437-444 (1989), and Nissinoff, J. Immunol 147(8):2429-2438 (1991)). For example, antibodies which bind to Brainiac-5 and competitively inhibit the Brainiac-5 multimerization and/or binding to ligand can be used to generate anti- idiotypes that "mimic" the Brainiac-5 mutimerization and/or binding domain and, as a consequence, bind to and neutralize Brainiac-5 and/or its ligand. Such neutralizing anti-idiotypes or Fab fragments of such anti-idiotypes can be used in therapeutic regimens to neutralize Brainiac-5 ligand. For example, such anti-idiotypic antibodies can be used to bind Brainiac-5 on the surface of the cell, and thereby block Brainiac-5- mediated cellular activation, proliferation, and/or differentiation. Disorders Related to the Immune and Nervous Systems Diagnosis The present inventors have discovered that Brainiac-5 is expressed not only in ovarian tumor cells, but also (using BLAST analysis of the HGS EST database) in bone maπow stromal cells and synovial sarcoma cells. For a number of immune and/or nervous system-related and/or developmental disorders, substantially altered (increased or decreased) levels of Brainiac-5 gene expression can be detected in immune and/or nervous system tissue or other cells or bodily fluids (e.g., sera, plasma, urine, synovial fluid or spinal fluid) taken from an individual having such a disorder, relative to a "standard" Brainiac-5 gene expression level, that is, the Brainiac-5 expression levels in immune and/or nervous system tissues or bodily fluids from an individual not having the immune and/or nervous system disorder. Thus, the invention provides a diagnostic method useful during diagnosis of a immune and/or nervous system disorder, which involves measuring the expression level of the gene encoding the Brainiac-5 polypeptides in immune and/or nervous system tissue or other cells or body fluid from an individual and comparing the measured gene expression level with a standard Brainiac-5 gene expression level, whereby an increase or decrease in the gene expression level compared to the standard is indicative of an immune and/or nervous system disorder. In particular, it is believed that certain tissues in mammals with cancer of the immune and nervous systems express significantly enhanced or reduced levels of the Brainiac-5 polypeptides and mRNA encoding the Brainiac-5 polypeptides when compared to a coπesponding "standard" level. Further, it is believed that enhanced levels of the Brainiac-5 polypeptides can be detected in certain body fluids (e.g., sera, plasma, urine, and spinal fluid) from mammals with such a cancer when compared to sera from mammals of the same species not having the cancer. In specific embodiments, cancers that may be treated, prevented, and/or diagnosed using Brainiac-5 polynucleotides, polypeptides, and/or agonists and/or antagonists of the invention include, but are not limited to, leukemia; acute leukemia (e.g., acute lymphocytic leukemia, acute myelocytic leukemia (specific examples thereof include myeloblastic, promyelocytic, myelomonocytic, monocytic, and erythroleukemia)); chronic leukemia (e.g., chronic myelocytic (granulocytic) leukemia, and chronic lymphocytic leukemia); polycythemia vera; lymphoma (e.g., Hodgkin's disease, and non-Hodgkin's disease); multiple myeloma; Waldenstrom's macroblogulinemia; heavy chain disease; and/or solid tumors (e.g., sarcomas and carcinomas (specific examples thereof include fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenomcarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinoma, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilms' tumor, cervical carcinoma, testicular cancer, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, menangioma, melanoma, neuroblastoma, and retinoblastoma). Thus, the invention provides a diagnostic method useful during diagnosis of an immune and/or nervous system disorder, including cancers of these systems, which involves measuring the expression level of the gene encoding the Brainiac-5 polypeptides in immune and/or nervous system tissue or other cells or body fluid from an individual and comparing the measured gene expression level with a standard Brainiac-5 gene expression level, whereby an increase or decrease in the gene expression level compared to the standard is indicative of an immune and/or nervous system disorder. Where a diagnosis of a disorder in the immune and/or nervous systems including diagnosis of a tumor, has already been made according to conventional methods, the present invention is useful as a prognostic indicator, whereby patients exhibiting enhanced or depressed Brainiac-5 gene expression will experience a worse clinical outcome relative to patients expressing the genes at a level nearer the standard level. By "assaying the expression level of the genes encoding the Brainiac-5 polypeptides" is intended qualitatively or quantitatively measuring or estimating the level of the Brainiac-5 polypeptides or the level of the mRNA encoding the Brainiac-5 polypeptides in a first biological sample either directly (e.g., by determining or estimating absolute protein level or mRNA level) or relatively (e.g., by comparing to the Brainiac-5 polypeptide levels or mRNA levels in a second biological sample). Preferably, the Brainiac-5 polypeptides level or mRNA level in the first biological sample is measured or estimated and compared to a standard Brainiac-5 polypeptide level or mRNA level, the standard being taken from a second biological sample obtained from an individual not having the disorder or being determined by averaging levels from a population of individuals not having a disorder of the immune and/or nervous systems. As will be appreciated in the art, once a standard Brainiac-5 polypeptide level or mRNA level is known, it can be used repeatedly as a standard for comparison. By "biological sample" is intended any biological sample obtained from an individual, body fluid, cell line, tissue culture, or other source which contains Brainiac-5 polypeptides or mRNA. As indicated, biological samples include body fluids (such as sera, plasma, urine, synovial fluid and spinal fluid) which contain free Brainiac-5 polypeptides, immune and/or nervous system tissue, and other tissue sources found to express complete or mature Brainiac-5 polypeptides or a Brainiac-5 receptor. Methods for obtaining tissue biopsies and body fluids from mammals are well known in the art. Where the biological sample is to include mRNA, a tissue biopsy is the prefeπed source. The present invention is useful for treating, preventing, and/or diagnosing various immune and/or nervous system-related disorders in mammals, preferably humans. A nonexclusive list of preferred mammals includes monkeys, apes, cats, dogs, cows, pigs, horses, rabbits, and humans. Humans are particularly prefeπed mammals. Such disorders include any disregulation of immune and/or nervous system cell and/or tissue function including, but not limited to Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Tourette's Syndrome, epilepsy, schizophrenia, mania, dementia, paranoia, obsessive compulsive disorder, panic disorder, learning disabilities, ALS, psychoses , autism, and altered behaviors, including disorders in feeding, sleep patterns, balance, and perception, neuronal survival; synapse formation; conductance; neural differentiation, autoimmunity, arthritis, leukemias, lymphomas, immunosuppression, immunity, humoral immunity, inflammatory bowel disease, myelosuppression, lymphoproliferative disorders, in the maintenance and differentiation of various hematopoietic lineages from early hematopoietic stem and committed progenitor cells, anemia, pancytopenia, leukopenia, thrombocytopenia or leukemia, bone maπow cell ex vivo culture, bone marrow transplantation, bone marrow reconstitution, radiotherapy or chemotherapy of neoplasia, asthma, immune deficiency diseases such as AIDS, rheumatoid arthritis, sepsis, acne, psoriasis, Grave's Disease, lymphocytic thyroiditis, hyperthyroidism, hypothyroidism, graft versus host reaction, graft versus host disease, transplant rejection, myelogenous leukemia, bone maπow fibrosis, and myeloproliferative disease, Huntington's disease gene and other neurodegenerative diseases including spinocerebullar ataxia types I and III, dentatorubropallidoluysian and spinal bulbar muscular atrophy, and the like. Total cellular RNA can be isolated from a biological sample using any suitable technique such as the single-step guanidinium-thiocyanate-phenol-chloroform method described by Chomczynski and Sacchi (Anal Biochem. 162: 156-159 (1987)). Levels of mRNA encoding the Brainiac-5 polypeptides are then assayed using any appropriate method. These include Northern blot analysis, S 1 nuclease mapping, the polymerase chain reaction (PCR), reverse transcription in combination with the polymerase chain reaction (RT-PCR), and reverse transcription in combination with the ligase chain reaction (RT-LCR). Assaying Brainiac-5 polypeptide levels in a biological sample can occur using antibody-based techniques. For example, Brainiac-5 polypeptide expression in tissues can be studied with classical immunohistological methods (Jalkanen, M., et al, J. Cell. Biol. 101:976-985 (1985); Jalkanen, ML, et al, J. Cell. Biol. 105:3087-3096 (1987)). Other antibody-based methods useful for detecting Brainiac-5 gene expression include immunoassays, such as the enzyme linked immunosorbent assay (ELISA) and the radioimmunoassay (RIA). Suitable antibody assay labels are known in the art and include enzyme labels, such as, glucose oxidase, and radioisotopes, such as iodine ( 125 I, 121 I), carbon ( 14 C), sulfur ( 35 S), tritium ( 3 H), indium ( 1 ,2 In), and technetium ( 99m Tc), and fluorescent labels, such as fluorescein and rhodamine, and biotin. In addition to assaying Brainiac-5 polypeptide levels in a biological sample obtained from an individual, Brainiac-5 polypeptides can also be detected in vivo by imaging. Antibody labels or markers for in vivo imaging of Brainiac-5 polypeptides include those detectable by X-radiography, NMR or ESR. For X-radiography, suitable labels include radioisotopes such as barium or cesium, which emit detectable radiation but are not overtly harmful to the subject. Suitable markers for NMR and ESR include those with a detectable characteristic spin, such as deuterium, which may be incoφorated into the antibody by labeling of nutrients for the relevant hybridoma. A Brainiac-5-specific antibody or antibody fragment, which has been labeled with an appropriate detectable imaging moiety, such as a radioisotope (for example, 1 1 I, u2 In, 99m Tc), a radio-opaque substance, or a material detectable by nuclear magnetic resonance, is introduced (for example, parenterally, subcutaneously or intraperitoneally) into the mammal to be examined for immune system disorder. It will be understood in the art that the size of the subject and the imaging system used will determine the quantity of imaging moiety needed to produce diagnostic images. In the case of a radioisotope moiety, for a human subject, the quantity of radioactivity injected will normally range from about 5 to 20 millicuries of 99m Tc. The labeled antibody or antibody fragment will then preferentially accumulate at the location of cells which contain Brainiac-5 polypeptides. In vivo tumor imaging is described by Burchiel and coworkers (Chapter 13 in Tumor Imaging: The Radiochemical Detection of Cancer, Burchiel, S. W. and Rhodes, B. A., eds., Masson Publishing Inc. (1982)). Treatment As noted above, Brainiac-5 polynucleotides and polypeptides are useful for diagnosis of conditions involving abnormally high or low expression of Brainiac-5 activities. Given the cells and tissues where Brainiac-5 polypeptides are expressed as well as the activities modulated by Brainiac-5 polypeptides, it is readily apparent that a substantially altered (increased or decreased) level of expression of Brainiac-5 polypeptides in an individual compared to the standard or "normal" level produces pathological conditions related to the bodily system(s) in which Brainiac-5 polypeptides are expressed and/or is active. It is well-known in the art that, in addition to a specific cellular function, cellular receptor molecules may also often be exploited by a virus as a means of initiating entry into a potential host cell. For example, it was recently discovered by Wu and colleagues (J. Exp. Med. 185: 1681-1691 (1997)) that the cellular chemokine receptor CCR5 functions not only as a cellular chemokine receptor, but also as a receptor for macrophage-tropic human immunodeficiency virus (HIV)-l. In addition, RANTES, MlP-la, and MlP-lb, which are agonists for the cellular chemokine receptor CCR5, inhibit entry of various strains of HIV-1 into susceptible cell lines (Cocchi, F., et al, Science 270: 1811-1815 (1995)). Thus, the invention also provides a method of treating, preventing, and/or diagnosing an individual exposed to, or infected with, a virus through the prophylactic or therapeutic administration of Brainiac-5 polypeptides, or an agonist or antagonist thereof, to block or disrupt the interaction of a viral particle with the Brainiac-5 receptors and, as a result, block the initiation or continuation of viral infectivity. The Brainiac-5 polypeptides of the present invention binds to the Brainiac-5 receptor and, as such, is likely to block immune-tropic viral infections. Agonists and antagonists of the Brainiac-5/Brainiac-5 Receptor interaction are also likely to interfere with immune-tropic viral infection. As a result, such an interaction is likely to interfere with the infectious life cycle of one or more immune-tropic viruses such as HIV- 1 , HIV-2, HTLV-III, HS V- 1 , HS V-2, and the like. The ability of Brainiac-5 polypeptides of the present invention, or agonists or antagonists thereof, to prophylactically or therapeutically block viral infection may be easily tested by the skilled artisan. For example, Simmons and coworkers (Science 276:276-279 (1997)) and Arenzana-Seisdedos and colleagues (Nαtwre 383:400 (1996)) each outline a method of observing suppression of HIV-1 infection by an antagonist of the CCR5 chemokine receptor and of the CC chemokine RAΝTES, respectively, in cultured peripheral blood mononuclear cells. Cells are cultured and infected with a virus, HIV-1 in both cases noted above. An agonist or antagonist of the CC chemokine or its receptor is then immediately added to the culture medium. Evidence of the ability of the agonist or antagonist of the chemokine or cellular receptor is determined by evaluating the relative success of viral infection at 3, 6, and 9 days postinfection. Administration of a pharmaceutical composition comprising an amount of an isolated Brainiac-5 polypeptide, or an agonist or antagonist thereof, of the invention to an individual either infected with a virus or at risk for infection with a virus is performed as described below. It will also be appreciated by one of ordinary skill that, since the Brainiac-5 polypeptides of the invention is a member of the Brainiac family, the mature secreted form of the polypeptide may be released in soluble form from the cells which express the Brainiac-5 polypeptides by proteolytic cleavage. Therefore, when the mature form of a Brainiac-5 polypeptide is added from an exogenous source to cells, tissues or the body of an individual, the polypeptide will exert its physiological activities on its target cells of that individual. Therefore, it will be appreciated that conditions caused by a decrease in the standard or normal level of Brainiac-5 activity in an individual, particularly disorders of the immune and/or nervous systems, can be treated, prevented, and/or diagnosed by administration of Brainiac-5 polypeptide (preferably in the form of the mature form of the polypeptide). Thus, the invention also provides a method of treatment, prevention, and/or diagnosis of an individual in need of an increased level of Brainiac-5 activity comprising administering to such an individual a pharmaceutical composition comprising an amount of an isolated Brainiac-5 polypeptide of the invention, particularly a mature form of the Brainiac-5 polypeptides of the invention, effective to increase the Brainiac-5 polypeptide activity level in such an individual. Brainiac-5 polypeptides are believed to elicit a potent cellular response including any genotypic, phenotypic, and/or moφhologic change to the cell, cell line, tissue, tissue culture or patient. As indicated, such cellular responses include not only < normal physiological responses to Brainiac-5, but also diseases associated with increased apoptosis or the inhibition of apoptosis. Apoptosis-programmed cell death- is a physiological mechanism involved in the deletion of peripheral B and/or T lymphocytes of the immune system, and its disregulation can lead to a number of different pathogenic processes (J.C. Ameisen, AIDS 5: 1197-1213 (1994); P.H. Krammer et α/., Curr. Opin. Immunol. 6:279-289 (1994)). Diseases associated with increased cell survival, or the inhibition of apoptosis, and which may be treated or prevented with polynucleotides, polypeptides, and/or agonists or antagonists of the invention, include, but are not limited to, cancers (such as follicular lymphomas, carcinomas with p53 mutations, and hormone-dependent tumors, including, but not limited to, colon cancer, cardiac tumors, pancreatic cancer, melanoma, retinoblastoma, glioblastoma, lung cancer, intestinal cancer, testicular cancer, stomach cancer, neuroblastoma, myxoma, myoma, lymphoma, endothelioma, osteoblastoma, osteoclastoma, osteosarcoma, chondrosarcoma, adenoma, breast cancer, prostate cancer, Kaposi's sarcoma and ovarian cancer); autoimmune disorders (such as systemic lupus erythematosus and immune-related glomerulonephritis rheumatoid arthritis); viral infections (such as heφes viruses, pox viruses and adenoviruses); inflammation; graft vs. host disease; acute graft rejection and chronic graft rejection. Thus, in prefeπed embodiments Brainiac-5 polynucleotides or polypeptides of the invention are used to treat, prevent, and/or diagnose autoimmune diseases and/or inhibit the growth, progression, and/or metastasis of cancers, including, but not limited to, those cancers disclosed herein, such as, for example, lymphocytic leukemias (including, for example, MLL and chronic lymphocytic leukemia (CLL)) and follicular lymphomas. In another embodiment Brainiac-5 polynucleotides or polypeptides of the invention are used to activate, differentiate or proliferate cancerous cells or tissue (e.g., B cell lineage related cancers (e.g., CLL and MLL), lymphocytic leukemia, or lymphoma) and thereby render the cells more vulnerable to cancer therapy (e.g., chemotherapy or radiation therapy). Moreover, in other embodiments, Brainiac-5 polynucleotides or polypeptides of the invention are used to inhibit the growth, progression, and or metastases of malignancies and related disorders such as leukemia (including acute leukemias (e.g., acute lymphocytic leukemia, acute myelocytic leukemia (including myeloblastic, promyelocytic, myelomonocytic, monocytic, and erythroleukemia)) and chronic leukemias (e.g., chronic myelocytic (granulocytic) leukemia and chronic lymphocytic leukemia)), polycythemia vera, lymphomas (e.g., Hodgkin's disease and non-Hodgkin's disease), multiple myeloma, Waldenstrom's macroglobulinemia, heavy chain disease, and solid tumors including, but not limited to, sarcomas and carcinomas such as fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilm's tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, menangioma, melanoma, neuroblastoma, and retinoblastoma. Diseases associated with increased apoptosis include AIDS; neurodegenerative disorders (such as Alzheimer's disease, Parkinson's disease, Amyotrophic lateral sclerosis, Retinitis pigmentosa, Cerebellar degeneration); myelodysplastic syndromes (such as aplastic anemia), ischemic injury (such as that caused by myocardial infarction, stroke and reperfusion injury), toxin-induced liver disease (such as that caused by alcohol), septic shock, cachexia and anorexia. Thus, in prefeπed embodiments Brainiac-5 polynucleotides or polypeptides of the invention are used to treat, prevent, and/or diagnose the diseases and disorders listed above. In prefeπed embodiments, Brainiac-5 polypeptides of the invention inhibit the growth of human histiocytic lymphoma U-937 cells in a dose-dependent manner. In additional preferred embodiments, Brainiac-5 polypeptides of the invention inhibit the growth of PC-3 cells, HT-29 cells, HeLa cells, MCF-7 cells, and A293 cells. In highly preferred embodiments, Brainiac-5 polynucleotides or polypeptides of the invention are used to inhibit growth, progression, and/or metastasis of prostate cancer, colon cancer, cervical carcinoma, and breast carcinoma. Because Brainiac-5 belongs to the Brainiac family, the polypeptides should also modulate angiogenesis. In addition, since Brainiac-5 inhibits immune cell functions, the polypeptides will have a wide range of anti-inflammatory activities. Brainiac-5 may be employed as an anti-neovascularizing agent to treat, prevent, and/or diagnose solid tumors by stimulating the invasion and activation of host defense cells, e.g., cytotoxic T cells and macrophages and by inhibiting the angiogenesis of tumors. Those of skill in the art will recognize other non-cancer indications where blood vessel proliferation is not wanted. They may also be employed to enhance host defenses against resistant chronic and acute infections, for example, myobacterial infections via the attraction and activation of microbicidal leukocytes. Brainiac-5 may also be employed to inhibit T-cell proliferation by the inhibition of IL-2 biosynthesis for the treatment of T-cell mediated auto-immune diseases and lymphocytic leukemias (including, for example, chronic lymphocytic leukemia (CLL)). Brainiac-5 may also be employed to stimulate wound healing, both via the recruitment of debris clearing and connective tissue promoting inflammatory cells. In this same manner, Brainiac-5 may also be employed to treat, prevent, and or diagnose other fibrotic disorders, including liver cirrhosis, osteoarthritis and pulmonary fibrosis. Brainiac-5 also increases the presence of eosinophils that have the distinctive function of killing the larvae of parasites that invade tissues, as in schistosomiasis, trichinosis and ascariasis. It may also be employed to regulate hematopoiesis, by regulating the activation and differentiation of various hematopoietic progenitor cells, for example, to release mature leukocytes from the bone maπow following chemotherapy, i.e., in stem cell mobilization. Brainiac-5 may also be employed to treat, prevent, and/or diagnose sepsis. Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5, can be used in the treatment of infectious agents. For example, by increasing the immune response, particularly increasing the proliferation and differentiation of B cells, infectious diseases may be treated. The immune response may be increased by either enhancing an existing immune response, or by initiating a new immune response. Alternatively, Brainiac-5 polynucleotides or polypeptides, or agonists or antagonists of Brainiac-5, may also directly inhibit the infectious agent, without necessarily eliciting an immune response. Viruses are one example of an infectious agent that can cause disease or symptoms that can be treated by Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5. Examples of viruses, include, but are not limited to the following DNA and RNA viruses and viral families: Arbovirus, Adenoviridae, Arenaviridae, Arterivirus, Birnaviridae, Bunyaviridae, Caliciviridae, Circoviridae, Coronaviridae, Dengue, EBV, HIV, Flaviviridae, Hepadnaviridae (Hepatitis), Heφesviridae (such as, Cytomegalovirus, Heφes Simplex, Heφes Zoster), Mononegavirus (e.g., Paramyxoviridae, Morbillivirus, Rhabdoviridae), Orthomyxoviridae (e.g., Influenza A, Influenza B, and parainfluenza), Papiloma virus, Papovaviridae, Parvoviridae, Picornaviridae, Poxviridae (such as Smallpox or Vaccinia), Reoviridae (e.g., Rotavirus), Retroviridae (HTLV-I, HTLV-II, Lentivirus), and Togaviridae (e.g., Rubivirus). Viruses falling within these families can cause a variety of diseases or symptoms, including, but not limited to: arthritis, bronchiolhtis, respiratory syncytial virus, encephalitis, eye infections (e.g., conjunctivitis, keratitis), chronic fatigue syndrome, hepatitis (A, B, C, E, Chronic Active, Delta), Japanese B encephalitis, Junin, Chikungunya, Rift Valley fever, yellow fever, meningitis, opportunistic infections (e.g., AIDS), pneumonia, Burkitt's Lymphoma, chickenpox, hemorrhagic fever, Measles, Mumps, Parainfluenza, Rabies, the common cold, Polio, leukemia, Rubella, sexually transmitted diseases, skin diseases (e.g., Kaposi's, warts), and viremia. Brainiac-5 polynucleotides or polypeptides, or agonists or antagonists of Brainiac-5, can be used to treat, prevent, diagnose, and/or detect any of these symptoms or diseases. In specific embodiments, Brainiac-5 polynucleotides, polypeptides, or agonists are used to treat, prevent, and/or diagnose: meningitis, Dengue, EBV, and/or hepatitis (e.g., hepatitis B). In an additional specific embodiment Brainiac-5 polynucleotides, polypeptides, or agonists are used to treat patients nonresponsive to one or more other commercially available hepatitis vaccines. In a further specific embodiment, Brainiac-5 polynucleotides, polypeptides, or agonists are used to treat, prevent, and/or diagnose AIDS. In an additional specific embodiment Brainiac-5 polypeptides, agonists, and/or antagonists are used to treat, prevent, and/or diagnose patients with cryptosporidiosis. Similarly, bacterial or fungal agents that can cause disease or symptoms and that can be treated by Brainiac-5 polynucleotides or polypeptides, or agonists or antagonists of Brainiac-5, include, but not limited to, the following Gram-Negative and Gram-positive bacteria and bacterial families and fungi: Actinomycetales (e.g., Corynebacterium, Mycobacterium, Norcardia), Cryptococcus neoformans, Aspergillosis, Bacillaceae (e.g., Anthrax, Clostridium), Bacteroidaceae, Blastomycosis, Bordetella, Boπelia (e.g., Boπelia burgdorferi, Brucellosis, Candidiasis, Campylobacter, Coccidioidomycosis, Cryptococcosis, Dermatocycoses, E. coli (e.g., Enterotoxigenic E. coli and Enterohemoπhagic E. coli), Enterobacteriaceae (Klebsiella, Salmonella (e.g., Salmonella typhi, and Salmonella paratyphi), Seπatia, Yersinia), Erysipelothrix, Helicobacter, Legionellosis, Leptospirosis, Listeria, Mycoplasmatales, Mycobacterium leprae, Vibrio cholerae, Neisseriaceae (e.g., Acinetobacter, Gonoπhea, Menigococcal), Meisseria meningitidis, Pasteurellacea Infections (e.g., Actinobacillus, Heamophilus (e.g., Heamophilus influenza type B), Pasteurella), Pseudomonas, Rickettsiaceae, Chlamydiaceae, Syphilis, Shigella spp., Staphylococcal, Meningiococcal, Pneumococcal and Streptococcal (e.g., Streptococcus pneumoniae and Group B Streptococcus). These bacterial or fungal families can cause the following diseases or symptoms, including, but not limited to: bacteremia, endocarditis, eye infections (conjunctivitis, tuberculosis, uveitis), gingivitis, opportunistic infections (e.g., AIDS related infections), paronychia, prosthesis-related infections, Reiter's Disease, respiratory tract infections, such as Whooping Cough or Empyema, sepsis, Lyme Disease, Cat-Scratch Disease, Dysentery, Paratyphoid Fever, food poisoning, Typhoid, pneumonia, Gonorrhea, meningitis (e.g., mengitis types A and B), Chlamydia, Syphilis, Diphtheria, Leprosy, Paratuberculosis, Tuberculosis, Lupus, Botulism, gangrene, tetanus, impetigo, Rheumatic Fever, Scarlet Fever, sexually transmitted diseases, skin diseases (e.g., cellulitis, dermatocycoses), toxemia, urinary tract infections, wound infections. Brainiac-5 polynucleotides or polypeptides, or agonists or antagonists of Brainiac-5, can be used to treat, prevent, diagnose, and/or detect any of these symptoms or diseases. In specific embodiments, Brainiac-5 polynucleotides, polypeptides, or agonists thereof are used to treat, prevent, and/or diagnose: tetanus, Diptheria, botulism, and/or meningitis type B. Moreover, parasitic agents causing disease or symptoms that can be treated by Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5, include, but not limited to, the following families or class: Amebiasis, Babesiosis, Coccidiosis, Cryptosporidiosis, Dientamoebiasis, Dourine, Ectoparasitic, Giardiasis, Helminthiasis, Leishmaniasis, Theileriasis, Toxoplasmosis, Trypanosomiasis, and Trichomonas and Sporozoans (e.g., Plasmodium virax, Plasmodium falciparium, Plasmodium malariae and Plasmodium ovale). These parasites can cause a variety of diseases or symptoms, including, but not limited to: Scabies, Trombiculiasis, eye infections, intestinal disease (e.g., dysentery, giardiasis), liver disease, lung disease, opportunistic infections (e.g., AIDS related), malaria, pregnancy complications, and toxoplasmosis. Brainiac-5 polynucleotides or polypeptides, or agonists or antagonists of Brainiac-5, can be used to treat, prevent, diagnose, and/or detect any of these symptoms or diseases. In specific embodiments, Brainiac-5 polynucleotides, polypeptides, or agonists thereof are used to treat, prevent, and/or diagnose malaria. In another embodiment, the invention provides a method of delivering compositions containing the polypeptides of the invention (e.g., compositions containing Brainiac-5 polypeptides or anti-Brainiac-5 antibodies associated with heterologous polypeptides, heterologous nucleic acids, toxins, or prodrugs) to targeted cells, such as, for example, cells expressing Brainiac-5 receptor. Brainiac-5 polypeptides or anti-Brainiac-5 antibodies of the invention may be associated with heterologous polypeptides, heterologous nucleic acids, toxins, or prodrugs via hydrophobic, hydrophilic, ionic and/or covalent interactions. In one embodiment, the invention provides a method for the specific delivery of compositions of the invention to cells by administering polypeptides of the invention (e.g., Brainiac-5 polypeptides or anti-Brainiac-5 antibodies) that are associated with heterologous polypeptides or nucleic acids. In one example, the invention provides a method for delivering a therapeutic protein into the targeted cell. In another example, the invention provides a method for delivering a single stranded nucleic acid (e.g., antisense or ribozymes) or double stranded nucleic acid (e.g., DNA that can integrate into the cell's genome or replicate episomally and that can be transcribed) into the targeted cell. In another embodiment, the invention provides a method for the specific destruction of cells (e.g., the destruction of tumor cells) by administering polypeptides of the invention (e.g., Brainiac-5 polypeptides or anti-Brainiac-5 antibodies) in association with toxins or cytotoxic prodrugs. By "toxin" is meant compounds that bind and activate endogenous cytotoxic effector systems, radioisotopes, holotoxins, modified toxins, catalytic subunits of toxins, or any molecules or enzymes not normally present in or on the surface of a cell that under defined conditions cause the cell's death. Toxins that may be used according to the methods of the invention include, but are not limited to, radioisotopes known in the art, compounds such as, for example, antibodies (or complement fixing containing portions thereof) that bind an inherent or induced endogenous cytotoxic effector system, thymidine kinase, endonuclease, RNAse, alpha toxin, ricin, abrin, Pseudomonas exotoxin A, diphtheria toxin, saporin, momordin, gelonin, pokeweed antiviral protein, alpha-sarcin and cholera toxin. "Toxin" also includes a cytostatic or cytocidal agent, a therapeutic agent or a radioactive metal ion, e.g., alpha-emitters such as, for example, 213 Bi. A cytotoxin or cytotoxic agent includes any agent that is detrimental to cells. Examples include paclitaxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cis- dichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents (e.g., vincristine and vinblastine). By "cytotoxic prodrug" is meant a non-toxic compound that is converted by an enzyme, normally present in the cell, into a cytotoxic compound. Cytotoxic prodrugs that may be used according to the methods of the invention include, but are not limited to, glutamyl derivatives of benzoic acid mustard alkylating agent, phosphate derivatives of etoposide or mitomycin C, cytosine arabinoside, daunorubisin, and phenoxyacetamide derivatives of doxorubicin. An additional condition, disease or symptom that can be treated, prevented, and/or diagnosed by Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5, is osteomyelitis. An additional condition, disease or symptom that can be treated, prevented, and/or diagnosed by Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5, is endocarditis. Preferably, treatment using Brainiac-5 polynucleotides or polypeptides, or agonists of Brainiac-5, could either be by administering an effective amount of Brainiac-5 polypeptide to the patient, or by removing cells from the patient, supplying the cells with Brainiac-5 polynucleotide, and returning the engineered cells to the patient (ex vivo therapy). Moreover, as further discussed herein, the Brainiac-5 polypeptide or polynucleotide can be used as an adjuvant in a vaccine to raise an immune response against infectious disease. Additional preferred embodiments of the invention include, but are not limited to, the use of Brainiac-5 and functional agonists thereof, in the following applications: Administration to an animal (e.g., mouse, rat, rabbit, hamster, guinea pig, pigs, micro-pig, chicken, camel, goat, horse, cow, sheep, dog, cat, non-human primate, and human, most preferably human) to boost the immune system to produce increased quantities of one or more antibodies (e.g., IgG, IgA, IgM, and IgE), to induce higher affinity antibody production (e.g., IgG, IgA, IgM, and IgE), and/or to increase an immune response. Administration to an animal (including, but not limited to, those listed above, and also including transgenic animals) incapable of producing functional endogenous antibody molecules or having an otherwise compromised endogenous immune system, but which is capable of producing human immunoglobuhn molecules by means of a reconstituted or partially reconstituted immune system from another animal (see, e.g., published PCT Application Nos. WO98/24893, WO/9634096, WO/9633735, and WO/9110741. The antagonists may be employed for instance to inhibit Brainiac-5-mediated chemotaxis and activation of macrophages and their precursors, and of neutrophils, basophils, B lymphocytes and some T-cell subsets, e.g., activated and CD8 cytotoxic T cells and natural killer cells, in certain auto-immune and chronic inflammatory and infective diseases. Examples of auto-immune diseases include multiple sclerosis, and insulin-dependent diabetes. The antagonists may also be employed to treat, prevent, and/or diagnose infectious diseases including silicosis, sarcoidosis, idiopathic pulmonary fibrosis by preventing the recruitment and activation of mononuclear phagocytes. They may also be employed to treat, prevent, and/or diagnose idiopathic hyper-eosinophilic syndrome by preventing eosinophil production and migration. Endotoxic shock may also be treated by the antagonists by preventing the migration of macrophages and their production of the Brainiac-5 polypeptides of the present invention. The antagonists may also be employed for treating atherosclerosis, by preventing monocyte infiltration in the artery wall. The antagonists may also be employed to treat, prevent, and/or diagnose histamine-mediated allergic reactions and immunological disorders including late phase allergic reactions, chronic urticaria, and atopic dermatitis by inhibiting chemokine-induced mast cell and basophil degranulation and release of histamine. IgE-mediated allergic reactions such as allergic asthma, rhinitis, and eczema may also be treated. The antagonists may also be employed to treat, prevent, and/or diagnose chronic and acute inflammation by preventing the attraction of monocytes to a wound area. They may also be employed to regulate normal pulmonary macrophage populations, since chronic and acute inflammatory pulmonary diseases are associated with sequestration of mononuclear phagocytes in the lung. Antagonists may also be employed to treat, prevent, and/or diagnose rheumatoid arthritis by preventing the attraction of monocytes into synovial fluid in the joints of patients. Monocyte influx and activation plays a significant role in the pathogenesis of both degenerative and inflammatory arthropathies. The antagonists may be employed to interfere with the deleterious cascades attributed primarily to IL-1 and TNF, which prevents the biosynthesis of other inflammatory cytokines. In this way, the antagonists may be employed to prevent inflammation. The antagonists may also be employed to inhibit prostaglandin-independent fever induced by Brainiac-5. The antagonists may also be employed to treat, prevent, and/or diagnose cases of bone maπow failure, for example, aplastic anemia and myelodysplastic syndrome. The antagonists may also be employed to treat, prevent, and/or diagnose asthma and allergy by preventing eosinophil accumulation in the lung. The antagonists may also be employed to treat, prevent, and/or diagnose subepithelial basement membrane fibrosis which is a prominent feature of the asthmatic lung. The antagonists may also be employed to treat, prevent, and/or diagnose lymphomas (e.g., one or more of the extensive, but not limiting, list of lymphomas provided herein). All of the above described applications as they may apply to veterinary medicine. Moreover, all applications described herein may also apply to veterinary medicine. Antibodies against Brainiac-5 may be employed to bind to and inhibit Brainiac-5 activity to treat, prevent, and/or diagnose ARDS, by preventing infiltration of neutrophils into the lung after injury. The antagonists and antagonists of the instant may be employed in a composition with a pharmaceutically acceptable caπier, e.g., as described hereinafter. Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof, are used to treat, prevent, and/or diagnose various immune system-related disorders and/or conditions associated with these disorders, in mammals, preferably humans. Many autoimmune disorders result from inappropriate recognition of self as foreign material by immune cells. This inappropriate recognition results in an immune response leading to the destruction of the host tissue. Therefore, the administration of Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof that can inhibit an immune response, particularly the proliferation, differentiation, or chemotaxis of T cells, may be an effective therapy in treating and/or preventing autoimmune disorders. Thus, in preferred embodiments, Brainiac-5 antagonists of the invention (e.g., polypeptide fragments of Brainiac-5 and anti-Brainiac-5 antibodies) are used to treat, prevent, and/or diagnose an autoimmune disorder. Such autoimmune disorders include, but are not limited to, autoimmune diseases such as, for example, autoimmune hemolytic anemia, autoimmune neonatal thrombocytopenia, autoimmunocytopenia, hemolytic anemia, antiphospholipid syndrome, dermatitis, allergic encephalomyelitis, glomerulonephritis, Multiple Sclerosis, Neuritis, Ophthalmia, Polyendocrinopathies, Puφura, Reiter's Disease, Stiff-Man Syndrome, Autoimmune Pulmonary Inflammation, Guillain-Barre Syndrome, insulin dependent diabetes mellitis, and autoimmune inflammatory eye disease. Additional autoimmune disorders (that are highly probable) include, but are not limited to, autoimmune thyroiditis (i.e., Hashimoto's thyroiditis) (often characterized, e.g., by cell-mediated and humoral thyroid cytotoxicity), systemic lupus erhthematosus (often characterized, e.g., by circulating and locally generated immune complexes), Goodpasture's syndrome (often characterized, e.g., by anti-basement membrane antibodies), Pemphigus (often characterized, e.g., by epidermal acantholytic antibodies), Receptor autoimmunities such as, for example, (a) Graves' Disease (often characterized, e.g., by TSH receptor antibodies), (b) Myasthenia Gravis (often characterized, e.g., by acetylcholine receptor antibodies), and (c) insulin resistance (often characterized, e.g., by insulin receptor antibodies), autoimmune hemolytic anemia (often characterized, e.g., by phagocytosis of antibody-sensitized RBCs), autoimmune thrombocytopenic puφura (often characterized, e.g., by phagocytosis of antibody-sensitized platelets. Additional autoimmune disorders (that are probable) include, but are not limited to, rheumatoid arthritis (often characterized, e.g., by immune complexes in joints), scleroderma with anti-collagen antibodies (often characterized, e.g., by nucleolar and other nuclear antibodies), mixed connective tissue disease (often characterized, e.g., by antibodies to extractable nuclear antigens (e.g., ribonucleoprotein)), polymyositis (often characterized, e.g., by nonhistone ANA), pernicious anemia (often characterized, e.g., by antiparietal cell, microsomes, and intrinsic factor antibodies), idiopathic Addison's disease (often characterized, e.g., by humoral and cell-mediated adrenal cytotoxicity, infertility (often characterized, e.g., by antispermatozoal antibodies), glomerulonephritis (often characterized, e.g., by glomerular basement membrane antibodies or immune complexes), bullous pemphigoid (often characterized, e.g., by IgG and complement in basement membrane), Sjogren's syndrome (often characterized, e.g., by multiple tissue antibodies, and/or a specific nonhistone ANA (SS-B)), diabetes millitus (often characterized, e.g., by cell-mediated and humoral islet cell antibodies), and adrenergic drug resistance (including adrenergic drug resistance with asthma or cystic fibrosis) (often characterized, e.g., by beta-adrenergic receptor antibodies). Additional autoimmune disorders (that are possible) include, but are not limited to, chronic active hepatitis (often characterized, e.g., by smooth muscle antibodies), primary biliary cirrhosis (often characterized, e.g., by mitchondrial antibodies), other endocrine gland failure (often characterized, e.g., by specific tissue antibodies in some cases), vitiligo (often characterized, e.g., by melanocyte antibodies), vasculitis (often characterized, e.g., by Ig and complement in vessel walls and/or low serum complement), post-MI (often characterized, e.g., by myocardial antibodies), cardiotomy syndrome (often characterized, e.g., by myocardial antibodies), urticaria (often characterized, e.g., by IgG and IgM antibodies to IgE), atopic dermatitis (often characterized, e.g., by IgG and IgM antibodies to IgE), asthma (often characterized, e.g., by IgG and IgM antibodies to IgE), and many other inflammatory, granulamatous, degenerative, and atrophic disorders. In a prefeπed embodiment, the autoimmune diseases and disorders and/or conditions associated with the diseases and disorders recited above are treated, prevented, and/or diagnosed using anti-Brainiac-5 antibodies. Similarly, allergic reactions and conditions, such as asthma (particularly allergic asthma) or other respiratory problems, may also be treated by Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof. Moreover, these molecules can be used to treat, prevent, and/or diagnose anaphylaxis, hypersensitivity to an antigenic molecule, or blood group incompatibility. Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof, may also be used to treat, prevent, and/or diagnose organ rejection or graft-versus-host disease (GVHD) and/or conditions associated therewith. Organ rejection occurs by host immune cell destruction of the transplanted tissue through an immune response. Similarly, an immune response is also involved in GVHD, but, in this case, the foreign transplanted immune cells destroy the host tissues. The administration of Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof, that inhibits an immune response, particularly the proliferation, differentiation, or chemotaxis of T-cells, may be an effective therapy in preventing organ rejection or GVHD. Similarly, Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof, may also be used to modulate inflammation. For example, Brainiac-5 polynucleotides or polypeptides of the invention and/or agonists and/or antagonists thereof, may inhibit the proliferation and differentiation of cells involved in an inflammatory response. These molecules can be used to treat, prevent, and/or diagnose inflammatory conditions, both chronic and acute conditions, including chronic prostatitis, granulomatous prostatitis and malacoplakia, inflammation associated with infection (e.g., septic shock, sepsis, or systemic inflammatory response syndrome (SIRS)), ischemia-reperfusion injury, endotoxin lethality, arthritis, complement-mediated hyperacute rejection, nephritis, cytokine or chemokine induced lung injury, inflammatory bowel disease, Crohn's disease, or resulting from over production of cytokines (e.g., TNF or IL-1.) In additional prefeπed embodiments, the present invention is directed to a method for enhancing apoptosis induced by a Brainiac-5 polypeptide, which involves administering to a cell which expresses a Brainiac-5 receptor an effective amount of Brainiac-5, analog or an agonist capable of increasing Brainiac-5-mediated signaling. Preferably, Brainiac-5-mediated signaling is increased to treat, prevent, and/or diagnose a disease wherein decreased apoptosis or decreased cytokine and adhesion molecule expression is exhibited. An agonist can include soluble forms of Brainiac-5 and monoclonal antibodies directed against the Brainiac-5 polypeptide. In a further embodiment, the present invention is directed to a method for inhibiting apoptosis induced by a Brainiac-5 polypeptide, which involves administering to a cell which expresses the Brainiac-5 receptor an effective amount of an antagonist capable of decreasing Brainiac-5-mediated signaling. Preferably, Brainiac-5-mediated signaling is decreased to treat, prevent, and/or diagnose a disease wherein increased apoptosis or NF-kappaB expression is exhibited. An antagonist can include soluble forms of Brainiac-5 and monoclonal antibodies directed against the Brainiac-5 polypeptide. Polynucleotides and/or polypeptides of the invention and/or agonists and/or antagonists thereof are useful in the diagnosis and treatment or prevention of a wide range of diseases and/or conditions. Such diseases and conditions include, but are not limited to, cancer (e.g., immune cell related cancers, breast cancer, prostate cancer, ovarian cancer, follicular lymphoma, cancer associated with mutation or alteration of p53, brain tumor, bladder cancer, uterocervical cancer, colon cancer, colorectal cancer, non-small cell carcinoma of the lung, small cell carcinoma of the lung, stomach cancer, etc.), lymphoproliferative disorders (e.g., lymphadenopathy), microbial (e.g., viral, bacterial, etc.) infection (e.g., HIV-1 infection, HIV-2 infection, heφesvirus infection (including, but not limited to, HSV-1, HSV-2, CMV, VZV, HHV-6, HHV-7, EBV), adenovirus infection, poxvirus infection, human papilloma virus infection, hepatitis infection (e.g., HAV, HBV, HCV, etc.), Helicobacter pylori infection, invasive Staphylococcia, etc.), parasitic infection, nephritis, bone disease (e.g., osteoporosis), atherosclerosis, pain, cardiovascular disorders (e.g., neovascularization, hypovascularization or reduced circulation (e.g., ischemic disease (e.g., myocardial infarction, stroke, etc.))), AIDS, allergy, inflammation, neurodegenerative disease (e.g., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, pigmentary retinitis, cerebellar degeneration, etc.), graft rejection (acute and chronic), graft vs. host disease, diseases due to osteomyelodysplasia (e.g., aplastic anemia, etc.), joint tissue destruction in rheumatism, liver disease (e.g., acute and chronic hepatitis, liver injury, and ciπhosis), autoimmune disease (e.g., multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, immune complex glomerulonephritis, autoimmune diabetes, autoimmune thrombocytopenic puφura, Grave's disease, Hashimoto's thyroiditis, etc.), cardiomyopathy (e.g., dilated cardiomyopathy), diabetes, diabetic complications (e.g., diabetic nephropathy, diabetic neuropathy, diabetic retinopathy), influenza, asthma, psoriasis, glomerulonephritis, septic shock, and ulcerative colitis. Polynucleotides and/or polypeptides of the invention and/or agonists and/or antagonists thereof are useful in promoting angiogenesis, wound healing (e.g., wounds, burns, and bone fractures). Polynucleotides and/or polypeptides of the invention and/or agonists and/or antagonists thereof are also useful as an adjuvant to enhance immune responsiveness to specific antigen, anti-viral immune responses,. More generally, polynucleotides and/or polypeptides of the invention and/or agonists and/or antagonists thereof are useful in regulating (i.e., elevating or reducing) immune response. For example, polynucleotides and/or polypeptides of the invention may be useful in preparation or recovery from surgery, trauma, radiation therapy, chemotherapy, and transplantation, or may be used to boost immune response and/or recovery in the elderly and immunocompromised individuals. Alternatively, polynucleotides and/or polypeptides of the invention and/or agonists and/or antagonists thereof are useful as immunosuppressive agents, for example in the treatment or prevention of autoimmune disorders. In specific embodiments, polynucleotides and/or polypeptides of the invention are used to treat or prevent chronic inflammatory, allergic or autoimmune conditions, such as those described herein or are otherwise known in the art. Formulations The Brainiac-5 polypeptide composition will be formulated and dosed in a fashion consistent with good medical practice, taking into account the clinical condition of the individual patient (especially the side effects of treatment, prevention, and/or diagnosis with Brainiac-5 polypeptides alone), the site of delivery of the Brainiac-5 polypeptide composition, the method of administration, the scheduling of administration, and other factors known to practitioners. The "effective amount" of Brainiac-5 polypeptide for puφoses herein is thus determined by such considerations. As a general proposition, the total pharmaceutically effective amount of Brainiac-5 polypeptide administered parenterally per dose will be in the range of about 1 μg/kg/day to 10 mg/kg/day of patient body weight, although, as noted above, this will be subject to therapeutic discretion. More preferably, this dose is at least 0.01 mg/kg/day, and most preferably for humans between about 0.01 and 1 mg/kg/day for the hormone. If given continuously, the Brainiac-5 polypeptide is typically administered at a dose rate of about 1 μg/kg/hour to about 50 μg/kg/hour, either by 1-4 injections per day or by continuous subcutaneous infusions, for example, using a mini- pump. An intravenous bag solution may also be employed. The length of treatment needed to observe changes and the interval following treatment for responses to occur appears to vary depending on the desired effect. Effective dosages of the compositions of the present invention to be administered may be determined through procedures well known to those in the art which address such parameters as biological half-life, bioavailability, and toxicity. Such determination is well within the capability of those skilled in the art, especially in light of the detailed disclosure provided herein. Bioexposure of an organism to Brainiac-5 polypeptide during therapy may also play an important role in determining a therapeutically and/or pharmacologically effective dosing regime. Variations of dosing such as repeated administrations of a relatively low dose of Brainiac-5 polypeptide for a relatively long period of time may have an effect which is therapeutically and/or pharmacologically distinguishable from that achieved with repeated administrations of a relatively high dose of Brainiac-5 for a relatively short period of time. See, for instance, the serum immunoglobuhn level experiments presented in Example 6. Using the equivalent surface area dosage conversion factors supplied by Freireich, E. J., et al. (Cancer Chemotherapy Reports 50(4):219-44 (1966)), one of < ordinary skill in the art is able to conveniently convert data obtained from the use of Brainiac-5 in a given experimental system into an accurate estimation of a pharmaceutically effective amount of Brainiac-5 polypeptide to be administered per dose in another experimental system. Experimental data obtained through the administration of Brainiac-5 in mice may be converted through the conversion factors supplied by Freireich, et al., to accurate estimates of pharmaceutically effective doses of Brainiac-5 in rat, monkey, dog, and human. The following conversion table (Table III) is a summary of the data provided by Freireich, et al. Table III gives approximate factors for converting doses expressed in terms of mg/kg from one species to an equivalent surface area dose expressed as mg/kg in another species tabulated. Table III. Equivalent Surface Area Dosage Conversion Factors. -TO - Mouse Rat Monkey Dog Human -FROM- (20g) (150p) (3.5kg) (8kg) 1 (60kg) Mouse 1 1/2 1/4 1/6 1/12 Rat 2 1 1/2 1/4 1/7 Monkey 4 2 1 3/5 1/3 Dog 6 4 5/3 1 1/2 Human 12 7 3 2 1 Thus, for example, using the conversion factors provided in Table III, a dose of 50 mg/kg in the mouse converts to an appropriate dose of 12.5 mg/kg in the monkey because (50 mg/kg) x (1/4) = 12.5 mg/kg. As an additional example, doses of 0.02, 0.08, 0.8, 2, and 8 mg/kg in the mouse equate to effect doses of 1.667 micrograms/kg, 6.67 micrograms/kg, 66.7 micrograms/kg, 166.7 micrograms/kg, and 0.667 mg/kg, respectively, in the human. Pharmaceutical compositions containing the Brainiac-5 polypeptides of the invention may be administered orally, rectally, parenterally, intracistemally, intravaginally, intraperitoneally, topically (as by powders, ointments, drops or transdermal patch), bucally, or as an oral or nasal spray. By "pharmaceutically acceptable caπier" is meant a non-toxic solid, semisolid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. In one embodiment, "pharmaceutically acceptable caπier" means a non-toxic solid, semisolid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. In a specific embodiment, "pharmaceutically acceptable" means approved by a regulatory agency of the federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly humans. Nonlimiting examples of suitable pharmaceutical caπiers according to this embodiment are provided in "Remington's Pharmaceutical Sciences" by E.W. Martin, and include sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred caπier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can be employed as liquid carriers, particularly for injectable solutions. The composition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. These compositions can take the form of solutions, suspensions, emulsion, tablets, pills, capsules, powders, sustained-release formulations and the like. The term "parenteral" as used herein refers to modes of administration which include intravenous, intramuscular, intraperitoneal, intrasternal, subcutaneous and intraarticular injection and infusion. The Brainiac-5 polypeptide is also suitably administered by sustained-release systems. Suitable examples of sustained-release compositions include semi-permeable polymer matrices in the form of shaped articles, e.g., films, or mirocapsules. Sustained-release matrices include polylactides (U.S. Pat. No. 3,773,919, EP 58,481), copolymers of L-glutamic acid and gamma-efhyl-L-glutamate (Sidman, LT., et al, Biopolymers 22:547-556 (1983)), poly (2- hydroxyethyl methacrylate; Langer, R., et al, J. Biomed. Mater. Res. 15:167-277 (1981), and Langer, R., Chem. Tech. 12:98-105 (1982)), ethylene vinyl acetate (Langer, R., et al, Id.) or poly-D- (-)-3-hydroxybutyric acid (EP 133,988). Sustained-release Brainiac-5 polypeptide compositions also include liposomally entrapped Brainiac-5 polypeptide. Liposomes containing Brainiac-5 polypeptides are prepared by methods known in the art (DE 3,218,121; Epstein, et al, Proc. Natl. Acad. Sci. (USA) 82:3688-3692 (1985); Hwang, et al, Proc. Natl. Acad. Sci. (USA) 77:4030-4034 (1980); EP 52,322; EP 36,676; EP 88,046; EP 143,949; EP 142,641; Japanese Pat. Appl. 83-118008; U.S. Pat. Nos. 4,485,045 and 4,544,545; and EP 102,324). Ordinarily, the liposomes are of the small (about 200- 800 Angstroms) unilamellar type in which the lipid content is greater than about 30 mol. percent cholesterol, the selected proportion being adjusted for the optimal Brainiac-5 polypeptide therapy. For parenteral administration, in one embodiment, the Brainiac-5 polypeptide is formulated generally by mixing it at the desired degree of purity, in a unit dosage injectable form (solution, suspension, or emulsion), with a pharmaceutically acceptable caπier, i.e., one that is non-toxic to recipients at the dosages and concentrations employed and is compatible with other ingredients of the formulation. For example, the formulation preferably does not include oxidizing agents and other compounds that are known to be deleterious to polypeptides. Generally, the formulations are prepared by contacting the Brainiac-5 polypeptide uniformly and intimately with liquid caπiers or finely divided solid caπiers or both. Then, if necessary, the product is shaped into the desired formulation. Preferably the caπier is a parenteral caπier, more preferably a solution that is isotonic with the blood of the recipient. Examples of such carrier vehicles include water, saline, Ringer's solution, and dextrose solution. Non-aqueous vehicles such as fixed oils and ethyl oleate are also useful herein, as well as liposomes. The carrier suitably contains minor amounts of additives such as substances that enhance isotonicity and chemical stability. Such materials are non-toxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, succinate, acetic acid, and other organic acids or their salts; antioxidants such as ascorbic acid; low molecular weight (less than about ten residues) polypeptides, e.g., polyarginine or tripeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyπolidone; amino acids, such as glycine, glutamic acid, aspartic acid, or arginine; monosaccharides, disaccharides, and other carbohydrates including cellulose or its derivatives, glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; counterions such as sodium; and/or nonionic surfactants such as polysorbates, poloxamers, or PEG. The Brainiac-5 polypeptide is typically formulated in such vehicles at a concentration of about 0.1 mg/ml to 100 mg/ml, preferably 1-10 mg/ml, at a pH of about 3 to 8. It will be understood that the use of certain of the foregoing excipients, caπiers, or stabilizers will result in the formation of Brainiac-5 polypeptide salts. Brainiac-5 polypeptide to be used for therapeutic administration must be sterile. Sterility is readily accomplished by filtration through sterile filtration membranes (e.g., 0.2 micron membranes). Therapeutic Brainiac-5 polypeptide compositions generally are placed into a container having a sterile access port, for example, an intravenous solution bag or vial having a stopper pierceable by a hypodermic injection needle. Brainiac-5 polypeptide ordinarily will be stored in unit or multi-dose containers, for example, sealed ampoules or vials, as an aqueous solution or as a lyophilized formulation for reconstitution. As an example of a lyophilized formulation, 10-ml vials are filled with 5 ml of sterile-filtered 1% (w/v) aqueous Brainiac-5 polypeptide solution, and the resulting mixture is lyophilized. The infusion solution is prepared by reconstituting the lyophilized Brainiac-5 polypeptide using bacteriostatic water- for-injection (WFI). The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. In addition, the polypeptides of the present invention may be employed in conjunction with other therapeutic compounds. The compositions of the invention may be administered alone or in combination with other adjuvants. Adjuvants that may be administered with the compositions of the invention include, but are not limited to, alum, alum plus deoxycholate (ImmunoAg), MTP-PE (Biocine Corp.). QS21 (Genentech, Inc.), BCG, and MPL. In a specific embodiment, compositions of the invention are administered in combination with alum. In another specific embodiment, compositions of the invention are administered in combination with QS-21. Further adjuvants that may be administered with the compositions of the invention include, but are not limited to, Monophosphoryl lipid immunomodulator, AdjuVax 100a, QS-21, QS-18, CRL1005, Aluminum salts, MF-59, and Virosomal adjuvant technology. Vaccines that may be administered with the compositions of the invention include, but are not limited to, vaccines directed toward protection against MMR (measles, mumps, rubella), polio, varicella, tetanus/diptheria, hepatitis A, hepatitis B, haemophilus influenzae B, whooping cough, pneumonia, influenza, Lyme's Disease, rotavirus, cholera, yellow fever, Japanese encephalitis, poliomyelitis, rabies, typhoid fever, and pertussis. Combinations may be administered either concomitantly, e.g., as an admixture, separately but simultaneously or concurrently; or sequentially. This includes presentations in which the combined agents are administered together as a therapeutic mixture, and also procedures in which the combined agents are administered separately but simultaneously, e.g., as through separate intravenous lines into the same individual. Administration "in combination" further includes the separate administration of one of the compounds or agents given first, followed by the second. The compositions of the invention may be administered alone or in combination with other therapeutic agents, including but not limited to, chemotherapeutic agents, antibiotics, antivirals, steroidal and non-steroidal anti- inflammatories, conventional immunotherapeutic agents and cytokines. Combinations may be administered either concomitantly, e.g., as an admixture, separately but simultaneously or concuπently; or sequentially. This includes presentations in which the combined agents are administered together as a therapeutic mixture, and also procedures in which the combined agents are administered separately but simultaneously, e.g., as through separate intravenous lines into the same individual. Administration "in combination" further includes the separate administration of one of the compounds or agents given first, followed by the second. In one embodiment, the compositions of the invention are administered in combination with members of the TNF family. TNF, TNF-related or TNF-like molecules that may be administered with the compositions of the invention include, but are not limited to, soluble forms of TNF-alpha, lymphotoxin-alpha (LT-alpha, also known as TNF-beta), LT-beta (found in complex heterotrimer LT-alpha2-beta), OPGL, FasL, CD27L, CD30L, CD40L, 4-1BBL, DcR3, OX40L, TNF-gamma (Inteπiational Publication No. WO 96/14328), AIM-I (International Publication No. WO 97/33899), AIM-II (International Publication No. WO 97/34911), APRIL (J. Exp. Med. 188(6):1185-1190), endokine-alpha (International Publication No. WO 98/07880), TR6 (International Publication No. WO 98/30694), OPG, and neutrokine- alpha (International Publication No. WO 98/18921 , OX40, and nerve growth factor (NGF), and soluble forms of Fas, CD30, CD27, CD40 and 4-IBB, TR2 (International Publication No. WO 96/34095), DR3 (International Publication No. WO 97/33904), DR4 (International Publication No. WO 98/32856), TR5 (International Publication No. WO 98/30693), TR6 (International Publication No. WO 98/30694), TR7 (International Publication No. WO 98/41629), TRANK, TR9 (International Publication No. WO 98/56892), TRIO (International Publication No. WO 98/54202), 312C2 (International Publication No. WO 98/06842), and TR12. In certain embodiments, compositions of the invention are administered in combination with antiretroviral agents, nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and/or protease inhibitors. Nucleoside reverse transcriptase inhibitors that may be administered in combination with the compositions of the invention, include, but are not limited to, RETRO VIR™ (zidovudine/AZT), VIDEX™ (didanosine/ddl), HIVID™ (zalcitabine/ddC), ZERIT™ (stavudine/d4T), EPIVIR™ (lamivudine/3TC), and COMBIVIR™ (zidovudine/lamivudine). Non-nucleoside reverse transcriptase inhibitors that may be administered in combination with the compositions of the invention, include, but are not limited to, VIRAMUNE™ (nevirapine), RESCRIPTOR™ (delavirdine), and SUSTIVA™ (efavirenz). Protease inhibitors that may be administered in combination with the compositions of the invention, include, but are not limited to, CRIXIVAN™ (indinavir), NORVIR™ (ritonavir), INVIRASE™ (saquinavir), and VIRACEPT™ (nelfinavir). In a specific embodiment, antiretroviral agents, nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and/or protease inhibitors may be used in any combination with compositions of the invention to treat, prevent, and/or diagnose AIDS and/or to treat, prevent, and/or diagnose HIV infection. In other embodiments, compositions of the invention may be administered in combination with anti-opportunistic infection agents. Anti-opportunistic agents that may be administered in combination with the compositions of the invention, include, but are not limited to, TRIMETHOPRIM-SULFAMETHOXAZOLE™, DAPSONE™, PENTAMIDINE™, ATOVAQUONE™, ISONIAZID™, RIFAMPIN™, PYRAZINAMIDE™, ETHAMBUTOL™, RIFABUTIN™, CLARITHROMYCIN™, AZITHROMYCIN™, GANCICLOVIR™, FOSCARNET™, CIDOFOVIR™, FLUCONAZOLE™, ITRACONAZOLE™, KETOCONAZOLE™, ACYCLOVIR™, FAMCICOLVIR™, PYRIMETHAMINE™, LEUCOVORIN™, NEUPOGEN™ (filgrastim/G-CSF), and LEUKINE™ (sargramostim/GM-CSF). In a specific embodiment, compositions of the invention are used in any combination with TRIMETHOPRIM-SULFAMETHOXAZOLE™, DAPSONE™, PENTAMIDINE™, and/or ATOVAQUONE™ to prophylactically treat, prevent, and/or diagnose an opportunistic Pneumocystis carinii pneumonia infection. In another specific embodiment, compositions of the invention are used in any combination with ISONIAZID™, RIFAMPIN™, PYRAZINAMIDE™, and/or ETHAMBUTOL™ to prophylactically treat, prevent, and/or diagnose an opportunistic Mycobacterium avium complex infection. In another specific embodiment, compositions of the invention are used in any combination with RIFABUTIN™, CLARITHROMYCIN™, and/or AZITHROMYCIN™ to prophylactically treat, prevent, and/or diagnose an opportunistic Mycobacterium tuberculosis infection. In another specific embodiment, compositions of the invention are used in any combination with GANCICLOVIR™, FOSCARNET™, and/or CIDOFOVIR™ to prophylactically treat, prevent, and/or diagnose an opportunistic cytomegalovirus infection. In another specific embodiment, compositions of the invention are used in any combination with FLUCONAZOLE™, ITRAςONAZOLE™, and or KETOCONAZOLE™ to prophylactically treat, prevent, and/or diagnose an opportunistic fungal infection. In another specific embodiment, compositions of the invention are used in any combination with ACYCLOVIR™ and/or FAMCICOLVIR™ to prophylactically treat, prevent, and/or diagnose an opportunistic heφes simplex virus type I and/or type II infection. In another specific embodiment, compositions of the invention are used in any combination with PYRIMETHAMINE™ and/or LEUCOVORIN™ to prophylactically treat, prevent, and/or diagnose an opportunistic Toxoplasma gondii infection. In another specific embodiment, compositions of the invention are used in any combination with LEUCOVORIN™ and/or NEUPOGEN™ to prophylactically treat, prevent, and/or diagnose an opportunistic bacterial infection. In a further embodiment, the compositions of the invention are administered in combination with an antiviral agent. Antiviral agents that may be administered with the compositions of the invention include, but are not limited to, acyclovir, ribavirin, amantadine, and remantidine. In a further embodiment, the compositions of the invention are administered in combination with an antibiotic agent. Antibiotic agents that may be administered with the compositions of the invention include, but are not limited to, amoxicillin, aminoglycosides, beta-lactam (glycopeptide), beta-lactamases, Clindamycin, chloramphenicol, cephalosporins, ciprofloxacin, ciprofloxacin, erythromycin, fluoroquinolones, macrolides, metronidazole, penicillins, quinolones, rifampin, streptomycin, sulfonamide, tetracyclines, trimethoprim, trimethoprim- sulfamthoxazole, and vancomycin. Conventional nonspecific immunosuppressive agents, that may be administered in combination with the compositions of the invention include, but are not limited to, steroids, cyclosporine, cyclosporine analogs, cyclophosphamide methylprednisone, prednisone, azathioprine, FK-506, 15-deoxyspergualin, and other immunosuppressive agents that act by suppressing the function of responding T cells. In specific embodiments, compositions of the invention are administered in combination with immunosuppressants. Immunosuppressants preparations that may be administered with the compositions of the invention include, but are not limited to, ORTHOCLONE™ (OKT3), SANDIMMUNE™/NEORAL™/SANGDYA™ (cyclosporin), PROGRAF™ (tacrolimus), CELLCEPT™ (mycophenolate), Azathioprine, glucorticosteroids, and RAPAMUNE™ (sirolimus). In a specific embodiment, immunosuppressants may be used to prevent rejection of organ or bone maπow transplantation. In an additional embodiment, compositions of the invention are administered alone or in combination with one or more intravenous immune globulin preparations. Intravenous immune globulin preparations that may be administered with the compositions of the invention include, but not limited to, GAMMAR™, IVEEGAM™, SANDOGLOBULIN™, GAMMAGARD S/D™, and GAMIMUNE™. In a specific embodiment, compositions of the invention are administered in combination with intravenous immune globulin preparations in transplantation therapy (e.g., bone marrow transplant). In an additional embodiment, the compositions of the invention are administered alone or in combination with an anti -inflammatory agent. Anti- inflammatory agents that may be administered with the compositions of the invention include, but are not limited to, glucocorticoids and the nonsteroidal anti- inflammatories, aminoarylcarboxylic acid derivatives, arylacetic acid derivatives, arylbutyric acid derivatives, arylcarboxylic acids, arylpropionic acid derivatives, pyrazoles, pyrazolones, salicylic acid derivatives, thiazinecarboxamides, e- acetamidocaproic acid, S-adenosylmethionine, 3-amino-4-hydroxybutyric acid, amixetrine, bendazac, benzydamine, bucolome, difenpiramide, ditazol, emorfazone, guaiazulene, nabumetone, nimesulide, orgotein, oxaceprol, paranyline, perisoxal, pifoxime, proquazone, proxazole, and tenidap. In another embodiment, compostions of the invention are administered in combination with a chemotherapeutic agent. Chemotherapeutic agents that may be administered with the compositions of the invention include, but are not limited to, antibiotic derivatives (e.g., doxorubicin, bleomycin, daunorubicin, and dactinomycin); antiestrogens (e.g., tamoxifen); antimetabolites (e.g., fluorouracil, 5-FU, methotrexate, floxuridine, interferon alpha-2b, glutamic acid, plicamycin, mercaptopurine, and 6- thioguanine); cytotoxic agents (e.g., carmustine, BCNU, lomustine, CCNU, cytosine arabinoside, cyclophosphamide, estramustine, hydroxyurea, procarbazine, mitomycin, busulfan, cis-platin, and vincristine sulfate); hormones (e.g., medroxyprogesterone, estramustine phosphate sodium, ethinyl estradiol, estradiol, megestrol acetate, methyltestosterone, diethylstilbestrol diphosphate, chlorotrianisene, and testolactone); nitrogen mustard derivatives (e.g., mephalen, chorambucil, mechlorethamine (nitrogen mustard) and thiotepa); steroids and combinations (e.g., bethamethasone sodium phosphate); and others (e.g., dicarbazine, asparaginase, mitotane, vincristine sulfate, vinblastine sulfate, and etoposide). In a specific embodiment, compositions of the invention are administered in combination with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) or any combination of the components of CHOP. In another embodiment, compositions of the invention are administered in combination with Rituximab. In a further embodiment, compositions of the invention are administered with Rituxmab and CHOP, or Rituxmab and any combination of the components of CHOP. In an additional embodiment, the compositions of the invention are administered in combination with cytokines. Cytokines that may be administered with the compositions of the invention include, but are not limited to, GM-CSF, G-CSF, IL2, IL3, IL4, IL5, IL6, IL7, IL10, IL12, IL13, IL15, anti-CD40, CD40L, IFN-alpha, IFN-beta, IFN-gamma, TNF-alpha, and TNF-beta. In another embodiment, compositions of the invention may be administered with any interleukin, including, but not limited to, IL-lalpha, IL-lbeta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL- 10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-19, IL-20, IL-21, and IL-22. In an additional embodiment, the compositions of the invention are administered with a chemokine. In another embodiment, the compositions of the invention are administered with chemokine beta-8, chemokine beta-1, and/or macrophage inflammatory protein-4. In a prefeπed embodiment, the compositions of the invention are administered with chemokine beta-8. In an additional embodiment, the compositions of the invention are administered in combination with an IL-4 antagonist. IL-4 antagonists that may be administered with the compositions of the invention include, but are not limited to: soluble IL-4 receptor polypeptides, multimeric forms of soluble IL-4 receptor polypeptides; anti-IL-4 receptor antibodies that bind the IL-4 receptor without transducing the biological signal elicited by IL-4, anti-IL4 antibodies that block binding of IL-4 to one or more IL-4 receptors, and muteins of IL-4 that bind IL-4 receptors but do not transduce the biological signal elicited by IL-4. Preferably, the antibodies employed according to this method are monoclonal antibodies (including antibody fragments, such as, for example, those described herein). In an additional embodiment, the compositions of the invention are administered in combination with hematopoietic growth factors. Hematopoietic growth factors that may be administered with the compositions of the invention include, but are not limited to, LEUKINE™ (SARGRAMOSTIM™) and NEUPOGEN™ (FILGRASTIM™). In an additional embodiment, the compositions of the invention are administered in combination with fibroblast growth factors. Fibroblast growth factors that may be administered with the compositions of the invention include, but are not limited to, FGF-1, FGF-2, FGF-3, FGF-4, FGF-5, FGF-6, FGF-7, FGF-8, FGF-9, FGF- 10, FGF-11, FGF- 12, FGF- 13, FGF- 14, and FGF- 15. Additionally, the compositions of the invention may be administered alone or in combination with other therapeutic regimens, including but not limited to, radiation therapy. Such combinatorial therapy may be administered sequentially and/or concomitantly. Agonists and Antagonists - Assays and Molecules The invention also provides a method of screening compounds to identify those which enhance or block the action of Brainiac-5 polypeptides on cells, such as its interaction with Brainiac-5 polypeptide-binding molecules such as receptor molecules. An agonist is a compound which increases the natural biological functions of Brainiac-5 polypeptides or which functions in a manner similar to Brainiac-5 polypeptides, while antagonists decrease or eliminate such functions. In another aspect of this embodiment the invention provides a method for identifying a receptor protein or other ligand-binding protein which binds specifically to a Brainiac-5 polypeptide. For example, a cellular compartment, such as a membrane or a preparation thereof, may be prepared from a cell that expresses a molecule that binds Brainiac-5 polypeptides. The preparation is incubated with labeled Brainiac-5 polypeptide and complexes of Brainiac-5 polypeptide bound to the receptor or other binding protein are isolated and characterized according to routine methods known in the art. Alternatively, the Brainiac-5 polypeptide may be bound to a solid support so that binding molecules solubilized from cells are bound to the column and then eluted and characterized according to routine methods. In the assay of the invention for agonists or antagonists, a cellular compartment, such as a membrane or a preparation thereof, may be prepared from a cell that expresses a molecule that binds Brainiac-5 polypeptide, such as a molecule of a signaling or regulatory pathway modulated by Brainiac-5 polypeptide. The preparation is incubated with labeled Brainiac-5 polypeptide in the absence or the presence of a candidate molecule which may be a Brainiac-5 polypeptide agonist or antagonist. The ability of the candidate molecule to bind the binding molecule is reflected in decreased binding of the labeled ligand. Molecules which bind gratuitously, i.e., without inducing the effects of Brainiac-5 polypeptide on binding the Brainiac-5 polypeptide-binding molecule, are most likely to be good antagonists. Molecules that bind well and elicit effects that are the same as or closely related to Brainiac-5 polypeptide are agonists. Brainiac-5 polypeptide-like effects of potential agonists and antagonists may by measured, for instance, by determining activity of a second messenger system following interaction of the candidate molecule with a cell or appropriate cell preparation, and comparing the effect with that of Brainiac-5 polypeptides or molecules that elicit the same effects as Brainiac-5 polypeptide. Second messenger systems that may be useful in this regard include but are not limited to AMP guanylate cyclase, ion channel or phosphoinositide hydrolysis second messenger systems. Another example of an assay for Brainiac-5 polypeptide antagonists is a competitive assay that combines Brainiac-5 polypeptides and a potential antagonist with membrane-bound Brainiac-5 polypeptide receptor molecules or recombinant Brainiac-5 polypeptide receptor molecules under appropriate conditions for a competitive inhibition assay. Brainiac-5 polypeptides can be labeled, such as by radioactivity, such that the number of Brainiac-5 polypeptide molecules bound to a receptor molecule can be determined accurately to assess the effectiveness of the potential antagonist. Potential antagonists include small organic molecules, peptides, polypeptides and antibodies that bind to a polypeptide of the invention and thereby inhibit or extinguish its activity. Potential antagonists also may be small organic molecules, a peptide, a polypeptide such as a closely related protein or antibody that binds the same sites on a binding molecule, such as a receptor molecule, without inducing Brainiac-5 polypeptide-induced activities, thereby preventing the action of Brainiac-5 polypeptides by excluding Brainiac-5 polypeptides from binding. Other potential antagonists include antisense molecules. Antisense technology can be used to control gene expression through antisense DNA or RNA or through triple-helix formation. Antisense techniques are discussed in a number of studies (for example, Okano, J. Neurochem. 56:560 (1991); "Oligodeoxynucleotides as Antisense Inhibitors of Gene Expression." CRC Press, Boca Raton, FL (1988)). Triple helix formation is discussed in a number of studies, as well (for instance, Lee, et al, Nucleic Acids Research 6:3073 (1979); Cooney, et al, Science 241:456 (1988); Dervan, et al, Science 251: 1360 (1991)). The methods are based on binding of a polynucleotide to a complementary DNA or RNA. For example, the 5' coding portion of a polynucleotide that encodes the mature polypeptide of the present invention may be used to design an antisense RNA ohgonucleotide of from about 10 to 40 base pairs in length. A DNA ohgonucleotide is designed to be complementary to a region of the gene involved in transcription thereby preventing transcription and the production of a Brainiac-5 polypeptide. The antisense RNA ohgonucleotide hybridizes to the mRNA in vivo and blocks translation of the mRNA molecule into a Brainiac-5 polypeptide. The ohgonucleotides described above can also be delivered to cells such that the antisense RNA or DNA may be expressed in vivo to inhibit production of Brainiac-5 polypeptides. In one embodiment, the Brainiac-5 antisense nucleic acid of the invention is produced intracellularly by transcription from an exogenous sequence. For example, a vector or a portion thereof, is transcribed, producing an antisense nucleic acid (RNA) of the invention. Such a vector would contain a sequence encoding the Brainiac-5 antisense nucleic acid. Such a vector can remain episomal or become chromosomally integrated, as long as it can be transcribed to produce the desired antisense RNA. Such vectors can be constructed by recombinant DNA technology methods standard in the art. Vectors can be plasmid, viral, or others know in the art, used for replication and expression in vertebrate cells. Expression of the sequence encoding Brainiac-5, or fragments thereof, can be by any promoter known in the art to act in vertebrate, preferably human cells. Such promoters can be inducible or constitutive. Such promoters include, but are not limited to, the SV40 early promoter region (Bernoist and Chambon, Nature 29:304-310 (1981), the promoter contained in the 3' long terminal repeat of Rous sarcoma virus (Yamamoto et al., Cell 22:787-797 (1980), the heφes thymidine promoter (Wagner et al., Proc. Natl. Acad. Sci. U.S.A. 78: 1441-1445 (1981), the regulatory sequences of the metahothionein gene (Brinster, et al., Nature 296:39-42 (1982)), etc. The antisense nucleic acids of the invention comprise a sequence complementary to at least a portion of an RNA transcript of a Brainiac-5 gene. However, absolute complementarity, although preferred, is not required. A sequence "complementary to at least a portion of an RNA," refeπed to herein, means a sequence having sufficient complementarity to be able to hybridize with the RNA, forming a stable duplex; in the case of double stranded Brainiac-5 antisense nucleic acids, a single strand of the duplex DNA may thus be tested, or triplex formation may be assayed. The ability to hybridize will depend on both the degree of complementarity and the length of the antisense nucleic acid Generally, the larger the hybridizing nucleic acid, the more base mismatches with a Brainiac-5 RNA it may contain and still form a stable duplex (or triplex as the case may be). One skilled in the art can ascertain a tolerable degree of mismatch by use of standard procedures to determine the melting point of the hybridized complex. Ohgonucleotides that are complementary to the 5' end of the message, e.g., the 5' untranslated sequence up to and including the AUG initiation codon, should work most efficiently at inhibiting translation. However, sequences complementary to the 3' untranslated sequences of mRNAs have been shown to be effective at inhibiting translation of mRNAs as well. See generally, Wagner, R., 1994, Nature 372:333-335. Thus, ohgonucleotides complementary to either the 5'- or 3'- non- translated, non- coding regions of Brainiac-5 shown in Figures 1A-B, could be used in an antisense approach to inhibit translation of endogenous Brainiac-5 mRNA. Ohgonucleotides complementary to the 5' untranslated region of the mRNA should include the complement of the AUG start codon. Antisense ohgonucleotides complementary to mRNA coding regions are less efficient inhibitors of translation but could be used in accordance with the invention. Whether designed to hybridize to the 5'-, 3'- or coding region of Brainiac-5 mRNA, antisense nucleic acids should be at least six nucleotides in length, and are preferably ohgonucleotides ranging from 6 to about 50 nucleotides in length. In specific aspects the ohgonucleotide is at least 10 nucleotides, at least 17 nucleotides, at least 25 nucleotides or at least 50 nucleotides. The polynucleotides of the invention can be DNA or RNA or chimeric mixtures or derivatives or modified versions thereof, single-stranded or double- stranded. The ohgonucleotide can be modified at the base moiety, sugar moiety, or phosphate backbone, for example, to improve stability of the molecule, hybridization, etc. The ohgonucleotide may include other appended groups such as peptides (e.g., for targeting host cell receptors in vivo), or agents facilitating transport across the cell membrane (see, e.g., Letsinger et al., 1989, Proc. Natl. Acad. Sci. U.S.A. 86:6553- 6556; Lemaitre et al., Proc. Natl. Acad. Sci. 84:648-652 (1987); PCT Publication No. WO88/09810, published December 15, 1988) or the blood-brain barrier (see, e.g., PCT Publication No. WO89/10134, published April 25, 1988), hybridization-triggered cleavage agents. (See, e.g., Krol et al., BioTechniques 6:958-976 (1988)) or intercalating agents. (See, e.g., Zon, Pharm. Res. 5:539-549 (1988)). To this end, the ohgonucleotide may be conjugated to another molecule, e.g., a peptide, hybridization triggered cross-linking agent, transport agent, hybridization-triggered cleavage agent, etc. The antisense ohgonucleotide may comprise at least one modified base moiety which is selected from the group including, but not limited to, 5-fluorouracil, 5- bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xantine, 4-acetylcytosine, 5- (carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5- carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, N6-isopentenyladenine, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2- methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine, 7- methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine, 5-methoxycarboxymethyluracil, 5-methoxyuracil, 2- methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid (v), wybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4- thiouracil, 5-methyluracil, uracil-5-oxy cetic acid methylester, uracil-5-oxyacetic acid (v), 5-methyl-2-thiouracil, 3-(3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2,6- diaminopurine. The antisense ohgonucleotide may also comprise at least one modified sugar moiety selected from the group including, but not limited to, arabinose, 2-fluoroarabinose, xylulose, and hexose. In yet another embodiment, the antisense ohgonucleotide comprises at least one modified phosphate backbone selected from the group including, but not limited to, a phosphorothioate, a phosphorodithioate, a phosphoramidothioate, a phosphoramidate, a phosphordiamidate, a methylphosphonate, an alkyl phosphotriester, and a formacetal or analog thereof. In yet another embodiment, the antisense ohgonucleotide is an a-anomeric ohgonucleotide. An a-anomeric ohgonucleotide forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual b-units, the strands run parallel to each other (Gautier et al., Nucl. Acids Res. 15:6625-6641 (1987)). The ohgonucleotide is a 2-0-methylribonucleotide (Inoue et al., Nucl. Acids Res. 15:6131- 6148 (1987)), or a chimeric RNA-DNA analogue (Inoue et al., FEBS Lett. 215:327- 330 (1997)). Polynucleotides of the invention may be synthesized by standard methods known in the art, e.g. by use of an automated DNA synthesizer (such as are commercially available from Biosearch, Applied Biosystems, etc.). As examples, phosphorothioate ohgonucleotides may be synthesized by the method of Stein et al. (Nucl. Acids Res. 16:3209 (1988)), methylphosphonate ohgonucleotides can be prepared by use of controlled pore glass polymer supports (Sarin et al., Proc. Natl. Acad. Sci. U.S.A. 85:7448-7451 (1988)), etc. While antisense nucleotides complementary to the Brainiac-5 coding region sequence could be used, those complementary to the transcribed untranslated region are most prefeπed. Potential antagonists according to the invention also include catalytic RNA, or a ribozyme (See, e.g., PCT International Publication WO 90/11364, published October 4, 1990; Sarver et al, Science 247:1222-1225 (1990). While ribozymes that cleave mRNA at site specific recognition sequences can be used to destroy Brainiac-5 mRNAs, the use of hammerhead ribozymes is prefeπed. Hammerhead ribozymes cleave mRNAs at locations dictated by flanking regions that form complementary base pairs with the target mRNA. The sole requirement is that the target mRNA have the following sequence of two bases: 5'-UG-3'. The construction and production of hammerhead ribozymes is well known in the art and is described more fully in Haseloff and Gerlach, Nature 334:585-591 (1988). There are numerous potential hammerhead ribozyme cleavage sites within the nucleotide sequence of Brainiac-5 (Figures 1A-B). Preferably, the ribozyme is engineered so that the cleavage recognition site is located near the 5' end of the Brainiac-5 mRNA; i.e., to increase efficiency and minimize the intracellular accumulation of non-functional mRNA transcripts. As in the antisense approach, the ribozymes of the invention can be composed of modified ohgonucleotides (e.g. for improved stability, targeting, etc.) and should be delivered to cells which express Brainiac-5 in vivo. DNA constructs encoding the ribozyme may be introduced into the cell in the same manner as described above for the introduction of antisense encoding DNA. A prefeπed method of delivery involves using a DNA construct "encoding" the ribozyme under the control of a strong constitutive promoter, such as, for example, pol III or pol II promoter, so that transfected cells will produce sufficient quantities of the ribozyme to destroy endogenous Brainiac-5 messages and inhibit translation. Since ribozymes unlike antisense molecules, are catalytic, a lower intracellular concentration is required for efficiency. Endogenous gene expression can also be reduced by inactivating or "knocking out" the Brainiac-5 gene and/or its promoter using targeted homologous recombination. (E.g., see Smithies et al., Nature 317:230-234 (1985); Thomas & Capecchi, Cell 51:503-512 (1987); Thompson et al., Cell 5:313-321 (1989); each of which is incoφorated by reference herein in its entirety). For example, a mutant, nonfunctional polynucleotide of the invention (or a completely unrelated DNA sequence) flanked by DNA homologous to the endogenous polynucleotide sequence (either the coding regions or regulatory regions of the gene) can be used, with or without a selectable marker and/or a negative selectable marker, to transfect cells that express polypeptides of the invention in vivo. In another embodiment, techniques known in the art are used to generate knockouts in cells that contain, but do not express the gene of interest. Insertion of the DNA construct, via targeted homologous recombination, results in inactivation of the targeted gene. Such approaches are particularly suited in research and agricultural fields where modifications to embryonic stem cells can be used to generate animal offspring with an inactive targeted gene (e.g., see Thomas & Capecchi 1987 and Thompson 1989, supra). However this approach can be routinely adapted for use in humans provided the recombinant DNA constructs are directly administered or targeted to the required site in vivo using appropriate viral vectors that will be apparent to those of skill in the art. The contents of each of the documents recited in this paragraph is herein incoφorated by reference in its entirety. In other embodiments, antagonists according to the present invention include soluble forms of Brainiac-5. Such soluble forms of the Brainiac-5, which may be naturally occurring or synthetic, antagonize Brainiac-5-mediated signaling by competing with native Brainiac-5 for binding to Brainiac-5 receptors and/or by forming a multimer that may or may not be capable of binding the receptor, but which is incapable of inducing signal transduction. Preferably, these antagonists inhibit Brainiac-5-mediated stimulation of lymphocyte (e.g., Dendritic cell, monocyte, macrophage, T cell, and/or B-cell) proliferation, differentiation, and/or activation. Antagonists of the present invention also include antibodies specific for TNF-family ligands (e.g., CD30) and Brainiac-5-Fc fusion proteins. Polyclonal and monoclonal antibody agonists or antagonists according to the present invention can be raised according to the methods disclosed in Tartaglia and Goeddel, J. Biol. Chem. 267(7):4304-4307(1992)); Tartaglia et al., Cell 73:213-216 (1993)), and PCT Application WO 94/09137 and are preferably specific to (i.e., bind uniquely to polypeptides of the invention having the amino acid sequence of SEQ ID NO:2. The term "antibody" (Ab) or "monoclonal antibody" (mAb) as used herein is meant to include intact molecules as well as fragments thereof (such as, for example, Fab and F(ab') fragments) which are capable of binding an antigen. Fab, Fab' and F(ab') fragments lack the Fc fragment intact antibody, clear more rapidly from the circulation, and may have less non-specific tissue binding of an intact antibody (Wahl et al., J. Nucl. Med., 24:316-325 (1983)). In a prefeπed method, antibodies according to the present invention are mAbs. Such mAbs can be prepared using hybridoma technology (Kohler and Millstein, Nature 256:495-497 (1975) and U.S. Patent No. 4,376,110; Harlow et al., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1988; Monoclonal Antibodies and Hybridomas: A New Dimension in Biological Analyses, Plenum Press, New York, NY, 1980; Campbell, "Monoclonal Antibody Technology," In: Laboratory Techniques in Biochemistry and Molecular Biology, Volume 13 (Burdon et al., eds.), Elsevier, Amsterdam (1984)). Proteins and other compounds which bind the Brainiac-5 domains are also candidate agonists and antagonists according to the present invention. Such binding compounds can be "captured" using the yeast two-hybrid system (Fields and Song, Nature 340:245-246 (1989)). A modified version of the yeast two- hybrid system has been described by Roger Brent and his colleagues (Gyuris, Cell 75:791-803 (1993); Zervos et al., Cell 72:223-232 (1993)). Such compounds are good candidate agonists and antagonists of the present invention. Other screening techniques include the use of cells which express the polypeptide of the present invention (for example, transfected CHO cells) in a system which measures extracellular pH changes caused by receptor activation, for example, as described in Science, 246:181-296 (1989). In another example, potential agonists or antagonists may be contacted with a cell which expresses the polypeptide of the present invention and a second messenger response, e.g., signal transduction may be measured to determine whether the potential antagonist or agonist is effective. Agonists according to the present invention include naturally occuπing and synthetic compounds such as, for example, TNF family ligand peptide fragments, transforming growth factor, neurotransmitters (such as glutamate, dopamine, N- methyl-D-aspartate), tumor suppressors (p53), cytolytic T cells and antimetabolites. Preferred agonists include chemotherapeutic drugs such as, for example, cisplatin, doxorubicin, bleomycin, cytosine arabinoside, nitrogen mustard, methotrexate and vincristine. Others include ethanol and -amyloid peptide. (Science 267:1457-1458 (1995)). Preferred agonists are fragments of Brainiac-5 polypeptides of the invention which stimulate lymphocyte (e.g., B cell) proliferation, differentiation and/or activation. Further preferred agonists include polyclonal and monoclonal antibodies raised against the Brainiac-5 polypeptides of the invention, or a fragment thereof. Such agonist antibodies raised against a TΝF-family receptor are disclosed in Tartaglia et al., Proc. Natl. Acad. Sci. USA 88:9292-9296 (1991); and Tartaglia et al., J. Biol. Chem. 267:4304- 4307(1992). See, also, PCT Application WO 94/09137. In an additional embodiment, immunoregulatory molecules such as, for example, IL2, IL3, IL4, IL5, IL6, IL7, IL10, IL12, IL13, IL15, anti-CD40, CD40L, IFΝ-gamma and TΝF-alpha, may be used as agonists of Brainiac-5 polypeptides of the invention which stimulate lymphocyte proliferation, differentiation and/or activation. In further embodiments of the invention, cells that are genetically engineered to express the polypeptides of the invention, or alternatively, that are genetically engineered not to express the polypeptides of the invention (e.g., knockouts) are administered to a patient in vivo. Such cells may be obtained from the patient (i.e., animal, including human) or an MHC compatible donor and can include, but are not limited to fibroblasts, bone marrow cells, blood cells (e.g., lymphocytes), adipocytes, muscle cells, endothelial cells etc. The cells are genetically engineered in vitro using < recombinant DΝA techniques to introduce the coding sequence of polypeptides of the invention into the cells, or alternatively, to disrupt the coding sequence and/or endogenous regulatory sequence associated with the polypeptides of the invention, e.g., by transduction (using viral vectors, and preferably vectors that integrate the transgene into the cell genome) or transfection procedures, including, but not limited to, the use of plasmids, cosmids, YACs, naked DNA, electroporation, liposomes, etc. The coding sequence of the polypeptides of the invention can be placed under the control of a strong constitutive or inducible promoter or promoter/enhancer to achieve expression, and preferably secretion, of the polypeptides of the invention. The engineered cells which express and preferably secrete the polypeptides of the invention can be introduced into the patient systemically, e.g., in the circulation, or intraperitoneally. Alternatively, the cells can be incoφorated into a matrix and implanted in the body, e.g., genetically engineered fibroblasts can be implanted as part of a skin graft; genetically engineered endothelial cells can be implanted as part of a lymphatic or vascular graft. (See, for example, Anderson et al. U.S. Patent No. 5,399,349; and Mulligan & Wilson, U.S. Patent No. 5,460,959 each of which is incoφorated by reference herein in its entirety). When the cells to be administered are non- autologous or non-MHC compatible cells, they can be administered using well known techniques which prevent the development of a host immune response against the introduced cells. For example, the cells may be introduced in an encapsulated form which, while allowing for an exchange of components with the immediate extracellular environment, does not allow the introduced cells to be recognized by the host immune system. In yet another embodiment of the invention, the activity of Brainiac-5 polypeptide can be reduced using a "dominant negative." To this end, constructs which encode defective Brainiac-5 polypeptide, such as, for example, mutants lacking all or a portion of a conserved domain, can be used in gene therapy approaches to diminish the activity of Brainiac-5 on appropriate target cells. For example, nucleotide sequences that direct host cell expression of Brainiac-5 polypeptide in which all or a portion of a conserved domain is altered or missing can be introduced into monocytic cells or other cells or tissues (either by in vivo or ex vivo gene therapy methods described herein or otherwise known in the art). Alternatively, targeted homologous recombination can be utilized to introduce such deletions or mutations into the subject's endogenous Brainiac-5 gene in monocytes. The engineered cells will express non-functional Brainiac-5 polypeptides (i.e., a ligand (e.g., multimer) that may be capable of binding, but which is incapable of inducing signal transduction). The agonists and antagonists may be employed in a composition with a pharmaceutically acceptable caπier, e.g., as described above. Gene Mapping The nucleic acid molecules of the present invention are also valuable for chromosome identification. The sequence is specifically targeted to and can hybridize with a particular location on an individual human chromosome. Moreover, there is a current need for identifying particular sites on the chromosome. Few chromosome marking reagents based on actual sequence data (repeat polymoφhisms) are presently available for marking chromosomal location. The mapping of DNAs to chromosomes according to the present invention is an important first step in coπelating those sequences with genes associated with disease. In certain prefeπed embodiments in this regard, the cDNA herein disclosed is used to clone genomic DNA of a Brainiac-5 gene. This can be accomplished using a variety of well known techniques and libraries, which generally are available commercially. The genomic DNA then is used for in situ chromosome mapping using well known techniques for this puφose. In addition, in some cases, sequences can be mapped to chromosomes by preparing PCR primers (preferably 15-25 bp) from the cDNA. Computer analysis of the 3' untranslated region of the gene is used to rapidly select primers that do not span more than one exon in the genomic DNA, thus complicating the amplification process. These primers are then used for PCR screening of somatic cell hybrids containing individual human chromosomes. Fluorescence in situ hybridization ("FISH") of a cDNA clone to a metaphase chromosomal spread can be used to provide a precise chromosomal location in one step. This technique can be used with probes from the cDNA as short as 50 or 60 bp (for a review of this technique, see Verma, et al, Human Chromosomes: A Manual Of Basic Techniques, Pergamon Press, New York (1988)). Once a sequence has been mapped to a precise chromosomal location, the physical position of the sequence on the chromosome can be correlated with genetic map data. Such data are found, for example, on the World Wide Web (McKusick, V. Mendelian Inheritance In Man, available on-line through Johns Hopkins University, Welch Medical Library). The relationship between genes and diseases that have been mapped to the same chromosomal region are then identified through linkage analysis (coinheritance of physically adjacent genes). Next, it is necessary to determine the differences in the cDNA or genomic sequence between affected and unaffected individuals. If a mutation is observed in some or all of the affected individuals but not in any normal individuals, then the mutation is likely to be the causative agent of the disease. Having generally described the invention, the same will be more readily understood by reference to the following examples, which are provided by way of illustration and are not intended as limiting. Examples Example 1: Expression and Purification of "His-tagged" Brainiac-5 in E. coli The novel pHE4 series of bacterial expression vectors, in particular, the pHE4- 5 vector may be used for bacterial expression in this example. (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, CA, 91311). pHE4-5/MPIFD23 vector plasmid DNA contains an insert which encodes another ORF. The construct was deposited with the American Type Culture Collection, 10801 University Boulevard, Manassas, Virginia 20110-2209, on September 30, 1997 and given Accession No. 209311. Using the NJe I and Asp 718 restriction sites flanking the iπelevant MPIF ORF insert, one of ordinary skill in the art could easily use cuπent molecular biological techniques to replace the iπelevant ORF in the pHE4-5 vector with the Brainiac-5 ORF of the present invention. The pHE4-5 bacterial expression vector includes a neomycin phosphotransferase gene for selection, an E. coli origin of replication, a T5 phage promoter sequence, two lac operator sequences, a Shine-Delgarno sequence, and the lactose operon repressor gene (laclq). These elements are aπanged such that an inserted DNA fragment encoding a polypeptide expresses that polypeptide with the six His residues (i.e., a "6 X His tag") covalently linked to the amino terminus of that polypeptide. The promoter and operator sequences of the pHE4-5 vector were made synthetically. Synthetic production of nucleic acid sequences is well known in the art (CLONETECH 95/96 Catalog, pages 215-216, CLONETECH, 1020 East Meadow Circle, Palo Alto, CA 94303). The DNA sequence encoding the desired portion of the Brainiac-5 polypeptide is amplified from the deposited cDNA clone using PCR ohgonucleotide primers which anneal to the amino terminal sequences of the desired portion of the Brainiac-5 polypeptide and to sequences in the deposited construct 3' to the cDNA coding sequence. Additional nucleotides containing restriction sites to facilitate cloning in the pHE4-5 vector are added to the 5' and 3' primer sequences, respectively. For cloning the Brainiac-5 polypeptide, the 5' primer has the sequence 5' CAA TTG GAT CCG TGG CAG AGG ACT TCG AGC 3' (SEQ ID NO: 11) containing the underlined Bam HI restriction site followed by 18 nucleotides of the amino terminal coding sequence of the Brainiac-5 sequence in SEQ ID NO:2. One of ordinary skill in the art would appreciate, of course, that the point in the protein coding sequence where the 5' primer begins may be varied to amplify a DNA segment encoding any desired portion of the complete Brainiac-5 polypeptide shorter or longer than the complete sequence of the polypeptide shown in Figures 1A and IB or in SEQ ID NO:2. The 3' primer has the sequence 5' GTA CGC AAG CTT GGA GTC CCA TTG GAA GGG 3' (SEQ ID NO: 12) containing the underlined Hin dill restriction site followed by 18 nucleotides complementary to the 3' end of the coding sequence of the Brainiac-5 DNA sequence shown in Figures 1A and IB (SEQ ID NO:l). The amplified Brainiac-5 DNA fragment and the vector pHE4-5 are digested with Bam HI and Hin dill and the digested DNAs are then ligated together. Insertion of the Brainiac-5 DNA into the restricted pHE4-5 vector places the Brainiac-5 polypeptide coding region downstream from the IPTG-inducible promoter and in- frame with an initiating AUG and the six histidine codons. The ligation mixture is transformed into competent E. coli cells using standard procedures such as those described by Sambrook and colleagues (Molecular Cloning: a Laboratory Manual, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY (1989)). E. coli strain M15/rep4, containing multiple copies of the plasmid pRΕP4, which expresses the lac repressor and confers kanamycin resistance ("Kanr"), is used in carrying out the illustrative example described herein. This strain, which is only one of many that are suitable for expressing Brainiac-5 polypeptide, is available commercially (QIAGEN, Inc., supra). Transformants are identified by their ability to grow on LB plates in the presence of ampicillin and kanamycin. Plasmid DNA is isolated from resistant colonies and the identity of the cloned DNA confirmed by restriction analysis, PCR and DNA sequencing. Clones containing the desired constructs are grown overnight ("O/N") in liquid culture in LB media supplemented with both ampicillin (100 μg/ml) and kanamycin (25 μg/ml). The O/N culture is used to inoculate a large culture, at a dilution of approximately 1:25 to 1:250. The cells are grown to an optical density at 600 nm ("OD600") of between 0.4 and 0.6. Isopropyl-beta-D-thiogalactopyranoside ("IPTG") is then added to a final concentration of 1 mM to induce transcription from the lac repressor sensitive promoter, by inactivating the lad repressor. Cells subsequently are incubated further for 3 to 4 hours. Cells then are harvested by centrifugation. The cells are then stiπed for 3-4 hours at 4°C in 6M guanidine-HCl, pH 8. The cell debris is removed by centrifugation, and the supernatant containing the Brainiac-5 polypeptide is loaded onto a nickel-nitrilo-tri-acetic acid ("Ni-NTA") affinity resin column (QIAGEN, Inc., supra). Proteins with a 6 x His tag bind to the Ni-NTA resin with high affinity and can be purified in a simple one-step procedure (for details see: The QIAexpressionist, 1995, QIAGEN, Inc., supra). Briefly the supernatant is loaded onto the column in 6 M guanidine-HCl, pH 8, the column is first washed with 10 volumes of 6 M guanidine-HCl, pH 8, then washed with 10 volumes of 6 M guanidine-HCl pH 6, and finally the Brainiac-5 polypeptide is eluted with 6 M guanidine-HCl, pH 5. The purified polypeptide is then renatured by dialyzing it against phosphate-buffered saline (PBS) or 50 mM Na-acetate, pH 6 buffer plus 200 mM NaCl. Alternatively, the protein can be successfully refolded while immobilized on the Ni-NTA column. The recommended conditions are as follows: renature using a linear 6M-1M urea gradient in 500 mM NaCl, 20% glycerol, 20 mM Tris/HCl pH 7.4, containing protease inhibitors. The renaturation should be performed over a period of 1.5 hours or more. After renaturation the proteins can be eluted by the addition of 250 0 mM immidazole. Immidazole is removed by a final dialyzing step against PBS or 50 mM sodium acetate pH 6 buffer plus 200 mM NaCl. The purified protein is stored at 4°C or frozen at -80° C. The following alternative method may be used to purify Brainiac-5 polypeptide expressed in E coli when it is present in the form of inclusion bodies. Unless 5 otherwise specified, all of the following steps are conducted at 4-10°C. Upon completion of the production phase of the E. coli fermentation, the cell culture is cooled to 4-10°C and the cells are harvested by continuous centrifugation at 15,000 φ (Heraeus Sepatech). On the basis of the expected yield of protein per unit weight of cell paste and the amount of purified protein required, an appropriate o amount of cell paste, by weight, is suspended in a buffer solution containing 100 mM Tris, 50 mM ΕDTA, pH 7.4. The cells are dispersed to a homogeneous suspension using a high shear mixer. The cells ware then lysed by passing the solution through a microfluidizer (Microfuidics, Coφ. or APV Gaulin, Inc.) twice at 4000-6000 psi. The homogenate is 5 then mixed with NaCl solution to a final concentration of 0.5 M NaCl, followed by centrifugation at 7000 x g for 15 min. The resultant pellet is washed again using 0.5M NaCl, 100 mM Tris, 50 mM ΕDTA, pH 7.4. The resulting washed inclusion bodies are solubilized with 1.5 M guanidine hydrochloride (GuHCl) for 2-4 hours. After 7000 x g centrifugation for 15 min., the pellet is discarded and the Brainiac-5 polypeptide-containing supernatant is incubated at 4°C overnight to allow further GuHCl extraction. Following high speed centrifugation (30,000 x g) to remove insoluble particles, the GuHCl solubilized protein is refolded by quickly mixing the GuHCl extract with 20 volumes of buffer containing 50 mM sodium, pH 4.5, 150 mM NaCl, 2 mM EDTA by vigorous stiπing. The refolded diluted protein solution is kept at 4°C without mixing for 12 hours prior to further purification steps. To clarify the refolded Brainiac-5 polypeptide solution, a previously prepared tangential filtration unit equipped with 0.16 micrometer membrane filter with appropriate surface area (e.g., Filtron), equilibrated with 40 mM sodium acetate, pH 6.0 is employed. The filtered sample is loaded onto a cation exchange resin (e.g., Poros HS-50, Perseptive Biosystems). The column is washed with 40 mM sodium acetate, pH 6.0 and eluted with 250 mM, 500 mM, 1000 mM, and 1500 mM NaCl in the same buffer, in a stepwise manner. The absorbance at 280 mm of the effluent is continuously monitored. Fractions are collected and further analyzed by SDS-PAGE. Fractions containing the Brainiac-5 polypeptide are then pooled and mixed with 4 volumes of water. The diluted sample is then loaded onto a previously prepared set of tandem columns of strong anion (Poros HQ-50, Perseptive Biosystems) and weak anion (Poros CM-20, Perseptive Biosystems) exchange resins. The columns are equilibrated with 40 mM sodium acetate, pH 6.0. Both columns are washed with 40 mM sodium acetate, pH 6.0, 200 mM NaCl. The CM-20 column is then eluted using a 10 column volume linear gradient ranging from 0.2 M NaCl, 50 mM sodium acetate, pH 6.0 to 1.0 M NaCl, 50 mM sodium acetate, pH 6.5. Fractions are collected under constant A 280 monitoring of the effluent. Fractions containing the Brainiac-5 polypeptide (determined, for instance, by 16% SDS-PAGE) are then pooled. The resultant Brainiac-5 polypeptide exhibits greater than 95% purity after the above refolding and purification steps. No major contaminant bands are observed from Commassie blue stained 16% SDS-PAGE gel when 5 micrograms of purified protein is loaded. The purified protein is also tested for endotoxin/LPS contamination, and typically the LPS content is less than 0.1 ng/ml according to LAL assays. Example 2: Cloning and Expression of Brainiac-5 polypeptide in a Baculovirus Expression System In this illustrative example, the plasmid shuttle vector pA2 GP is used to insert the cloned DNA encoding the mature protein, lacking its naturally associated secretory signal (leader) sequence, into a baculovirus to express a Brainiac-5 polypeptide, using a baculovirus leader and standard methods as described by Summers and colleagues (A Manual of Methods for Baculovirus Vectors and Insect Cell Culture Procedures, Texas Agricultural Experimental Station Bulletin No. 1555 (1987)). This expression vector contains the strong polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus (AcMNPV) followed by the secretory signal peptide (leader) of the baculovirus gp67 protein and convenient restriction sites such as Bam HI, Xba I and Asp 718. The polyadenylation site of the simian virus 40 ("SV40") is used for efficient polyadenylation. For easy selection of recombinant virus, the plasmid contains the beta-galactosidase gene from E. coli under control of a weak Drosophila promoter in the same orientation, followed by the polyadenylation signal of the polyhedrin gene. The inserted genes are flanked on both sides by viral sequences for cell-mediated homologous recombination with wild-type viral DNA to generate viable virus that expresses the cloned polynucleotide. Many other baculovirus vectors could be used in place of the vector above, such as pA2, pAc373, pVL941 and pAcIMl, as one skilled in the art would readily appreciate, as long as the construct provides appropriately located signals for transcription, translation, secretion and the like, including a signal peptide and an in- frame AUG as required. Such vectors are described, for instance, by Luckow and colleagues (Virology 170:31-39 (1989)). The cDNA sequence encoding the Brainiac-5 polypeptide in the deposited clone, is amplified using PCR ohgonucleotide primers corresponding to the 5' and 3' sequences of the gene. The 5' primer has the sequence 5'-CGC GGA TCC GCC ATC ATG GTG GCA GAG GAC TTC GAG C-3' (SEQ ID NO: 13) containing the underlined Bam HI restriction enzyme site followed by 19 nucleotides of the sequence of the Brainiac-5 polypeptide shown in SEQ ID NO:2, beginning with the currently known N-terminus. The 3' primer has the sequence 5'-CAC TTA GGT ACC GGA GTC CCA TTG GAA GGG-3' (SEQ ID NO: 14) containing the underlined Asp 718 restriction site followed by 18 nucleotides complementary to the carboxy-terminal sequence in Figures 1A and IB. The amplified fragment is isolated from a 1 % agarose gel using a commercially available kit ("Geneclean," BIO 101 Inc., La Jolla, Ca.). The fragment then is digested with Bam HI and Asp 718 and again is purified on a 1% agarose gel. This fragment is designated herein FI. The plasmid is digested with the restriction enzymes Bam HI and Asp 718 and optionally, can be dephosphorylated using calf intestinal phosphatase, using routine procedures known in the art. The DNA is then isolated from a 1 % agarose gel using a commercially available kit ("Geneclean" BIO 101 Inc., La Jolla, Ca.). This vector DNA is designated herein "VI". Fragment FI and the dephosphorylated plasmid VI are ligated together with T4 DNA ligase. E. coli HB101 or other suitable E. coli hosts such as XL-1 Blue (Statagene Cloning Systems, La Jolla, CA) cells are transformed with the ligation mixture and spread on culture plates. Bacteria are identified that contain the plasmid with the human Brainiac-5 gene by digesting DNA from individual colonies using Bam HI and Asp 718 and then analyzing the digestion product by gel electrophoresis. The sequence of the cloned fragment is confirmed by DNA sequencing. This plasmid is designated herein pA2GPBrainiac-5. Five μg of the plasmid pA2GPBrainiac-5 is co-transfected with 1.0 μg of a commercially available linearized baculovirus DNA ("BaculoGold™ baculovirus DNA", Pharmingen, San Diego, CA), using the lipofection method described by Feigner and colleagues (Proc. Natl Acad. Sci. USA 84:7413-7417 (1987)). One μg of BaculoGold™ virus DNA and 5 μg of the plasmid pA2GPBrainiac-5 are mixed in a sterile well of a microtiter plate containing 50 μl of serum-free Grace's medium (Life Technologies Inc., Gaithersburg, MD). Afterwards, 10 μl Lipofectin plus 90 μl Grace's medium are added, mixed and incubated for 15 minutes at room temperature. Then the transfection mixture is added drop-wise to Sf9 insect cells (ATCC CRL 1711) seeded in a 35 mm tissue culture plate with 1 ml Grace's medium without serum. The plate is then incubated for 5 hours at 27°C. The transfection solution is then removed from the plate and 1 ml of Grace's insect medium supplemented with 10% fetal calf serum is added. Cultivation is then continued at 27°C for four days. After four days the supernatant is collected and a plaque assay is performed, as described by Summers and Smith (supra). An agarose gel with "Blue Gal" (Life Technologies Inc., Gaithersburg) is used to allow easy identification and isolation of gal-expressing clones, which produce blue-stained plaques. (A detailed description of o a "plaque assay" of this type can also be found in the user's guide for insect cell culture and baculovirology distributed by Life Technologies Inc., Gaithersburg, page 9-10). After appropriate incubation, blue stained plaques are picked with the tip of a micropipettor (e.g., Eppendorf). The agar containing the recombinant viruses is then resuspended in a microcentrifuge tube containing 200 μl of Grace's medium and the 5 suspension containing the recombinant baculovirus is used to infect Sf9 cells seeded in 35 mm dishes. Four days later the supematants of these culture dishes are harvested and then they are stored at 4°C. The recombinant virus is called V-Brainiac-5. To verify the expression of the Brainiac-5 gene Sf9 cells are grown in Grace's medium supplemented with 10% heat-inactivated FBS. The cells are infected with the 0 recombinant baculovirus V-Brainiac-5 at a multiplicity of infection ("MOI") of about 2. If radiolabeled polypeptides are desired, 6 hours later the medium is removed and is replaced with SF900 II medium minus methionine and cysteine (available from Life Technologies Inc., Rockville, MD). After 42 hours, 5 μCi of 5 S-methionine and 5 μCi 35 S-cysteine (available from Amersham) are added. The cells are further incubated for 5 16 hours and then are harvested by centrifugation. The polypeptides in the supernatant as well as the intracellular polypeptides are analyzed by SDS-PAGE followed by autoradiography (if radiolabeled). Example 3: Cloning and Expression of Brainiac-5 in Mammalian Cells A typical mammalian expression vector contains the promoter element, which mediates the initiation of transcription of mRNA, the polypeptide coding sequence, and signals required for the termination of transcription and polyadenylation of the transcript. Additional elements include enhancers, Kozak sequences and intervening sequences flanked by donor and acceptor sites for RNA splicing. Highly efficient transcription can be achieved with the early and late promoters from SV40, the long terminal repeats (LTRs) from Retroviruses, e.g., RSV, HTLV-I, HIV-1 and the early promoter of the cytomegalovirus (CMV). However, cellular elements can also be used (e.g., the human actin promoter). Suitable expression vectors for use in practicing the present invention include, for example, vectors such as pSVL and pMSG (Pharmacia, Uppsala, Sweden), pRSVcat (ATCC 37152), pSV2dhfr (ATCC 37146) and pBC12MI (ATCC 67109). Mammalian host cells that could be used include, human Hela, 293, H9 and Jurkat cells, mouse NIH3T3 and C127 cells, Cos 1, Cos 7 and CV1, quail QC1-3 cells, mouse L cells and Chinese hamster ovary (CHO) cells. Alternatively, the gene can be expressed in stable cell lines that contain the gene integrated into a chromosome. The co-transfection with a selectable marker such as dhfr, gpt, neomycin, hygromycin allows the identification and isolation of the transfected cells. The transfected gene can also be amplified to express large amounts of the encoded polypeptide. The DHFR (dihydrofolate reductase) marker is useful to develop cell lines that carry several hundred or even several thousand copies of the gene of interest. Another useful selection marker is the enzyme glutamine synthase (GS; Muφhy, et al, Biochem J. 227:277-279 (1991); Bebbington, et al, Bio/Technology 10:169-175 (1992)). Using these markers, the mammalian cells are < grown in selective medium and the cells with the highest resistance are selected. These cell lines contain the amplified gene(s) integrated into a chromosome. Chinese hamster ovary (CHO) and NSO cells are often used for the production of polypeptides. The expression vectors pC 1 and pC4 contain the strong promoter (LTR) of the Rous Sarcoma Virus (Cullen, et al, Mol. Cel. Biol. 5:438-447 (1985)) plus a fragment of the CMV-enhancer (Boshart, et al, Cell 41:521-530 (1985)). Multiple cloning sites, e.g., with the restriction enzyme cleavage sites Bam HI, Xba I and Asp 718, facilitate the cloning of the gene of interest. The vectors contain in addition the 3' intron, the polyadenylation and termination signal of the rat preproinsulin gene. Example 3(a): Cloning and Expression in COS Cells The expression plasmid, pBrainiac-5HA, is made by cloning a portion of the cDNA encoding the mature form of the Brainiac-5 polypeptide into the expression vector pcDNAI/Amp or pcDNAIII (which can be obtained from Invitrogen, Inc.). The expression vector pcDNAI/amp contains: (1) an E. coli origin of replication effective for propagation in E. coli and other prokaryotic cells; (2) an ampicillin resistance gene for selection of plasmid-containing prokaryotic cells; (3) an SV40 origin of replication for propagation in eukaryotic cells; (4) a CMV promoter, a polylinker, an SV40 intron; (5) several codons encoding a hemagglutinin fragment (i.e., an "HA" tag to facilitate purification) followed by a termination codon and polyadenylation signal aπanged so that a cDNA can be conveniently placed under expression control of the CMV promoter and operably linked to the SV40 intron and the polyadenylation signal by means of restriction sites in the polylinker. The HA tag corresponds to an epitope derived from the influenza hemagglutinin protein described by Wilson and colleagues (Cell 37:767 (1984)). The fusion of the HA tag to the target polypeptide allows easy detection and recovery of the recombinant polypeptide with an antibody that recognizes the HA epitope. pcDNAIII contains, in addition, the selectable neomycin marker. A DNA fragment encoding the Brainiac-5 polypeptide is cloned into the polylinker region of the vector so that recombinant polypeptide expression is directed by the CMV promoter. The plasmid construction strategy is as follows. The Brainiac-5 cDNA of the deposited clone is amplified using primers that contain convenient restriction sites, much as described above for construction of vectors for expression of Brainiac-5 in E. coli. Suitable primers include the following, which are used in this example. The 5' primer, containing the underlined Bam HI site, a Kozak sequence (in italics), an AUG start codon, and 16 nucleotides of the 5' coding region of the Brainiac-5 polypeptide, has the following sequence: 5' CGC GGA TCC GCCATC ATG GTG GCA GAG GAC TTC GAG C 3' (SEQ ID NO: 15). The 3' primer, containing the underlined Asp 718 and 17 of nucleotides complementary to the 3' coding sequence immediately before the stop codon, has the following sequence: 5'-CAC TTA GGT ACC GGA GTC CCA TTG GAA GGG-3' (SEQ ID NO: 16). The PCR amplified DNA fragment and the vector, pcDNAI/Amp, are digested with Bam HI and Asp 718 and then ligated. The ligation mixture is transformed into E. coli strain SURE (Stratagene Cloning Systems, La Jolla, CA 92037), and the transformed culture is plated on ampicillin media plates which then are incubated to allow growth of ampicillin resistant colonies. Plasmid DNA is isolated from resistant colonies and examined by restriction analysis or other means for the presence of the fragment encoding the complete Brainiac-5 polypeptide For expression of recombinant Brainiac-5, COS cells are transfected with an expression vector, as described above, using DEAE-dextran, as described, for instance, by Sambrook and coworkers (Molecular Cloning: a Laboratory Manual, Cold Spring Laboratory Press, Cold Spring Harbor, New York (1989)). Cells are incubated under conditions for expression of Brainiac-5 by the vector. Expression of the Brainiac-5-HA fusion polypeptide is detected by radiolabeling and immunoprecipitation, using methods described in, for example Harlow and colleagues (Antibodies: A Laboratory Manual, 2nd Ed. ; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York (1988)). To this end, two days after transfection, the cells are labeled by incubation in media containing 35 S- cysteine for 8 hours. The cells and the media are collected, and the cells are washed and the lysed with detergent-containing RIPA buffer: 150 mM NaCl, 1 % NP-40, 0.1 % SDS, 1% NP-40, 0.5% DOC, 50 mM TRIS, pH 7.5, as described by Wilson and colleagues (supra). Polypeptides are precipitated from the cell lysate and from the culture media using an HA-specific monoclonal antibody. The precipitated polypeptides then are analyzed by SDS-PAGE and autoradiography. An expression product of the expected size is seen in the cell lysate, which is not seen in negative controls. Example 3(b): Cloning and Expression in CHO Cells The vector pC4 is used for the expression of Brainiac-5 polypeptide. Plasmid pC4 is a derivative of the plasmid pSV2-dhfr (ATCC Accession No. 37146). The plasmid contains the mouse DHFR gene under control of the SV40 early promoter. Chinese hamster ovary- or other cells lacking dihydrofolate activity that are transfected with these plasmids can be selected by growing the cells in a selective medium (alpha minus MEM, Life Technologies) supplemented with the chemotherapeutic agent methotrexate. The amplification of the DHFR genes in cells resistant to methotrexate (MTX) has been well documented (see, e.g., Alt, F. W., et al, J. Biol. Chem. 253: 1357-1370 (1978); Hamlin, J. L. and Ma, C. Biochem. et Biophys. Ada, 1097: 107-143 (1990); Page, M. J. and Sydenham, M. A. Biotechnology 9:64-68 (1991)). Cells grown in increasing concentrations of MTX develop resistance to the drug by oveφroducing the target enzyme, DHFR, as a result of amplification of the DHFR gene. If a second gene is linked to the DHFR gene, it is usually co- amplified and over-expressed. It is known in the art that this approach may be used to develop cell lines carrying more than 1,000 copies of the amplified gene(s). Subsequently, when the methotrexate is withdrawn, cell lines are obtained which contain the amplified gene integrated into one or more chromosome(s) of the host cell. Plasmid pC4 contains for expressing the gene of interest the strong promoter of the long terminal repeat (LTR) of the Rouse Sarcoma Virus (Cullen, et al, Mol. Cell. Biol. 5:438-447 (1985)) plus a fragment isolated from the enhancer of the immediate early gene of human cytomegalovirus (CMV; Boshart, et al, Cell 41:521-530 (1985)). Downstream of the promoter are the following single restriction enzyme cleavage sites that allow the integration of the genes: Bam HI, Xba I, and Asp 718. Behind these cloning sites the plasmid contains the 3' intron and polyadenylation site of the rat preproinsulin gene. Other high efficiency promoters can also be used for the expression, e.g., the human β-actin promoter, the SV40 early or late promoters or the long terminal repeats from other retroviruses, e.g., HIV and HTLVI. Clontech's Tet- Off and Tet-On gene expression systems and similar systems can be used to express the Brainiac-5 polypeptide in a regulated way in mammalian cells (Gossen, M., and Bujard, H. Proc. Natl Acad. Sci. USA 89:5547-5551 (1992)). For the polyadenylation of the mRNA other signals, e.g., from the human growth hormone or globin genes can be used as well. Stable cell lines carrying a gene of interest integrated into the chromosomes can also be selected upon co-transfection with a selectable marker such as gpt, G418 or hygromycin. It is advantageous to use more than one selectable marker in the beginning, e.g., G418 plus methotrexate. The plasmid pC4 is digested with the restriction enzymes Bam HI and Asp 118 and then dephosphorylated using calf intestinal phosphates by procedures known in the art. The vector is then isolated from a 1% agarose gel. The DNA sequence encoding the complete Brainiac-5 polypeptide is amplified using PCR ohgonucleotide primers coπesponding to the 5' and 3' sequences of the desired portion of the gene. The 5' primer contains a Bam HI restriction site, a Kozak sequence, an AUG start codon, and 16 nucleotides of the 5' coding region of the Brainiac-5 polypeptide, and is shown in SEQ ID NO: 15. The 3' primer, contains an Asp 718 restriction site, and 17 of nucleotides complementary to the 3' coding sequence immediately before the stop codon, and is shown in SEQ ID NO: 16. The amplified fragment is digested with the endonucleases Bam HI and Asp 718 and then purified again on a 1% agarose gel. The isolated fragment and the dephosphorylated vector are then ligated with T4 DNA ligase. E. coli HB 101 or XL-1 Blue cells are then transformed and bacteria are identified that contain the fragment inserted into plasmid pC4 using, for instance, restriction enzyme analysis. Chinese hamster ovary cells lacking an active DHFR gene are used for transfection. Five μg of the expression plasmid pC4 is cotransfected with 0.5 μg of the plasmid pSVneo using lipofectin (Feigner, et al, supra). The plasmid pSV2-neo contains a dominant selectable marker, the neo gene from Tn5 encoding an enzyme that confers resistance to a group of antibiotics including G418. The cells are seeded in alpha minus MEM supplemented with 1 mg/ml G418. After 2 days, the cells are trypsinized and seeded in hybridoma cloning plates (Greiner, Germany) in alpha minus MEM supplemented with 10, 25, or 50 ng/ml of metothrexate plus 1 mg/ml G418. After about 10-14 days single clones are trypsinized and then seeded in 6- well petri dishes or 10 ml flasks using different concentrations of methotrexate (50 nM, 100 nM, 200 nM, 400 nM, 800 nM). Clones growing at the highest concentrations of methotrexate are then transfeπed to new 6-well plates containing even higher concentrations of methotrexate (1 μM, 2 μM, 5 μM, 10 mM, 20 mM). The same procedure is repeated until clones are obtained which grow at a concentration of 100-200 μM. Expression of the desired gene product is analyzed, for instance, by SDS-PAGE and Western blot or by reversed phase HPLC analysis. Example 4: Tissue distribution of Brainiac-5 mRNA expression Northern blot analysis is carried out to examine Brainiac-5 gene expression in human tissues, using methods described by, among others, Sambrook and colleagues (supra). A cDNA probe containing the entire nucleotide sequence of the Brainiac-5 polypeptide (SEQ ID NO: 1) is labeled with 32 P using the red/prime™ DNA labeling system (Amersham Life Science), according to manufacturer's instructions. After labeling, the probe is purified using a CHROMA SPIN- 100™ column (Clontech Laboratories, Inc.), according to manufacturer's protocol number PT1200-1. The purified labeled probe is then used to examine various human tissues for Brainiac-5 mRNA. Multiple Tissue Northern (MTN) blots containing various human tissues (H) or human immune system tissues (IM) are obtained from Clontech and are examined with the labeled probe using ExpressHyb™ hybridization solution (Clontech) according to manufacturer's protocol number PT1190-1. Following hybridization and washing, the blots are mounted and exposed to film at -70°C overnight, and films developed according to standard procedures. Example 5: Production of an Antibody (a) Hybridoma Technology The antibodies of the present invention can be prepared by a variety of methods. (See, Current Protocols, Chapter 2.) As one example of such methods, cells expressing Brainiac-5 are administered to an animal to induce the production of sera containing polyclonal antibodies. In a prefeπed method, a preparation of Brainiac-5 protein is prepared and purified to render it substantially free of natural contaminants. Such a preparation is then introduced into an animal in order to produce polyclonal antisera of greater specific activity. Monoclonal antibodies specific for protein Brainiac-5 are prepared using hybridoma technology. (Kohler et al., Nature 256:495 (1975); Kohler et al., Eur. J. Immunol. 6:511 (1976); Kohler et al., Eur. J. Immunol. 6:292 (1976); Hammerling et al., in: Monoclonal Antibodies and T-Cell Hybridomas, Elsevier, N.Y., pp. 563-681 (1981)). In general, an animal (preferably a mouse) is immunized with Brainiac-5 polypeptide or, more preferably, with a secreted Brainiac-5 polypeptide-expressing cell. Such polypeptide-expressing cells are cultured in any suitable tissue culture medium, preferably in Earle's modified Eagle's medium supplemented with 10% fetal bovine serum (inactivated at about 56°C), and supplemented with about 10 g/1 of nonessential amino acids, about 1,000 U/ml of penicillin, and about 100 μg/ml of streptomycin. The splenocytes of such mice are extracted and fused with a suitable myeloma cell line. Any suitable myeloma cell line may be employed in accordance with the present invention; however, it is preferable to employ the parent myeloma cell line (SP2O), available from the ATCC. After fusion, the resulting hybridoma cells are selectively maintained in HAT medium, and then cloned by limiting dilution as described by Wands et al. (Gastroenterology 80:225-232 (1981). The hybridoma cells obtained through such a selection are then assayed to identify clones which secrete antibodies capable of binding the Brainiac-5 polypeptide. Alternatively, additional antibodies capable of binding to Brainiac-5 polypeptide can be produced in a two-step procedure using anti-idiotypic antibodies. Such a method makes use of the fact that antibodies are themselves antigens, and therefore, it is possible to obtain an antibody which binds to a second antibody. In accordance with this method, protein specific antibodies are used to immunize an animal, preferably a mouse. The splenocytes of such an animal are then used to produce hybridoma cells, and the hybridoma cells are screened to identify clones which produce an antibody whose ability to bind to the Brainiac-5 protein-specific antibody can be blocked by Brainiac-5. Such antibodies comprise anti-idiotypic antibodies to the Brainiac-5 protein-specific antibody and are used to immunize an animal to induce formation of further Brainiac-5 protein-specific antibodies. For in vivo use of antibodies in humans, an antibody is "humanized". Such antibodies can be produced using genetic constructs derived from hybridoma cells producing the monoclonal antibodies described above. Methods for producing chimeric and humanized antibodies are known in the art and are discussed infra. (See, for review, Moπison, Science 229: 1202 (1985); Oi et al., BioTechniques 4:214 (1986); Cabilly et al., U.S. Patent No. 4,816,567; Taniguchi et al., EP 171496; Moπison et al., EP 173494; Neuberger et al., WO 8601533; Robinson et al., WO 8702671; Boulianne et al., Nature 312:643 (1984); Neuberger et al., Nature 314:268 (1985).) (b) Isolation Of Antibody Fragments Directed Against Brainiac-5 From A Library OfscFvs Naturally occuπing V-genes isolated from human PBLs are constructed into a library of antibody fragments which contain reactivities against Brainiac-5 to which the donor may or may not have been exposed (see e.g., U.S. Patent 5,885,793 incorporated herein by reference in its entirety). Rescue of the Library. A library of scFvs is constructed from the RNA of human PBLs as described in PCT publication WO 92/01047. To rescue phage displaying antibody fragments, approximately 109 E. coli harboring the phagemid are used to inoculate 50 ml of 2xTY containing 1 % glucose and 100 μg/ml of ampicillin (2xTY-AMP-GLU) and grown to an O.D. of 0.8 with shaking. Five ml of this culture is used to innoculate 50 ml of 2xTY-AMP-GLU, 2 x 108 TU of delta gene 3 helper (Ml 3 delta gene III, see PCT publication WO 92/01047) are added and the culture incubated at 37°C for 45 minutes without shaking and then at 37°C for 45 minutes with shaking. The culture is centrifuged at 4000 r.p.m. for 10 min. and the pellet resuspended in 2 liters of 2xTY containing 100 μg/ml ampicillin and 50 ug/ml kanamycin and grown overnight. Phage are prepared as described in PCT publication WO 92/01047. M13 delta gene III is prepared as follows: M13 delta gene III helper phage does not encode gene III protein, hence the phage(mid) displaying antibody fragments have a greater avidity of binding to antigen. Infectious M13 delta gene III particles are made by growing the helper phage in cells harboring a pUC19 derivative supplying the wild type gene III protein during phage moφhogenesis. The culture is incubated for 1 hour at 37° C without shaking and then for a further hour at 37°C with shaking. Cells are spun down (IEC-Centra 8,400 r.p.m. for 10 min), resuspended in 300 ml 2xTY broth containing 100 μg ampicillin/ml and 25 μg kanamycin/ml (2xTY- AMP- KAN) and grown overnight, shaking at 37°C. Phage particles are purified and concentrated from the culture medium by two PEG-precipitations (Sambrook et al., 1990), resuspended in 2 ml PBS and passed through a 0.45 μm filter (Minisart NML; Sartorius) to give a final concentration of approximately 1013 transducing units/ml (ampicillin-resistant clones). Panning of the Library. Immunotubes (Nunc) are coated overnight in PBS with 4 ml of either 100 μg/ml or 10 μg/ml of a polypeptide of the present invention. Tubes are blocked with 2% Marvel-PBS for 2 hours at 37°C and then washed 3 times in PBS. Approximately 1013 TU of phage is applied to the tube and incubated for 30 minutes at room temperature tumbling on an over and under turntable and then left to stand for another 1.5 hours. Tubes are washed 10 times with PBS 0.1% Tween-20 and 10 times with PBS. Phage are eluted by adding 1 ml of 100 mM triethylamine and rotating 15 minutes on an under and over turntable after which the solution is immediately neutralized with 0.5 ml of 1.0M Tris-HCl, pH 7.4. Phage are then used to infect 10 ml of mid-log E. coli TGI by incubating eluted phage with bacteria for 30 minutes at 37°C. The E. coli are then plated on TYE plates containing 1% glucose and 100 μg/ml ampicillin. The resulting bacterial library is then rescued with delta gene 3 helper phage as described above to prepare phage for a subsequent round of selection. This process is then repeated for a total of 4 rounds of affinity purification with tube-washing increased to 20 times with PBS, 0.1% Tween-20 and 20 times with PBS for rounds 3 and 4. Characterization of Binders. Eluted phage from the 3rd and 4th rounds of selection are used to infect E. coli HB 2151 and soluble scFv is produced (Marks, et al., 1991) from single colonies for assay. ELISAs are performed with microtitre plates coated with either 10 pg/ml of the polypeptide of the present invention in 50 mM bicarbonate pH 9.6. Clones positive in ELISA are further characterized by PCR fingeφrinting (see, e.g., PCT publication WO 92/01047) and then by sequencing. It will be clear that the invention may be practiced otherwise than as particularly described in the foregoing description and examples. Numerous modifications and variations of the present invention are possible in light of the above teachings and, therefore, are within the scope of the appended claims. The entire disclosure of all publications (including patents, patent applications, journal articles, laboratory manuals, books, or other documents) cited herein are hereby incoφorated by reference. Further, the Sequence Listing submitted herewith, and the Sequence Listing submitted in copending application Serial No. 60/113,804, filed December 23, 1998, in both computer-readable and paper formats (in each case), are hereby incoφorated by reference in their entireties. INDICATIONS RELATING TO A DEPOSITED MICROORGANISM (PCT Rule 13 bis) Form PCT/RO/134 (July 1992) ATCC Deposit No. 203572 CANADA The applicant requests that, until either a Canadian patent has been issued on the basis of an application or the application has been refused, or is abandoned and no longer subject to reinstatement, or is withdrawn, the Commissioner of Patents only authorizes the furnishing of a sample ofthe deposited biological material refeπed to in the application to an independent expert nominated by the Commissioner, the applicant must, by a written statement, inform the International Bureau accordingly before completion of technical preparations for publication ofthe international application. NORWAY The applicant hereby requests that the application has been laid open to public inspection (by the Norwegian Patent Office), or has been finally decided upon by the Norwegian Patent Office without having been laid open inspection, the furnishing of a sample shall only be effected to an expert in the art. The request to this effect shall be filed by the applicant with the Norwegian Patent Office not later than at the time when the application is made available to the public under Sections 22 and 33(3) ofthe Norwegian Patents Act. If such a request has been filed by the applicant, any request made by a third party for the furnishing of a sample shall indicate the expert to be used. That expert may be any person entered on the list of recognized experts drawn up by the Norwegian Patent Office or any person approved by the applicant in the individual case. AUSTRALIA The applicant hereby gives notice that the furnishing of a sample of a microorganism shall only be effected prior to the grant of a patent, or prior to the lapsing, refusal or withdrawal of the application, to a person who is a skilled addressee without an interest in the invention (Regulation 3.25(3) ofthe Australian Patents Regulations). FINLAND The applicant hereby requests that, until the application has been laid open to public inspection (by the National Board of Patents and Regulations), or has been finally decided upon by the National Board of Patents and Registration without having been laid open to public inspection, the furnishing of a sample shall only be effected to an expert in the art. UNITED KINGDOM The applicant hereby requests that the furnishing of a sample of a microorganism shall only be made available to an expert. The request to this effect must be filed by the applicant with the International Bureau before the completion ofthe technical preparations for the international publication ofthe application. ATCC Deposit No. 203572 DENMARK The applicant hereby requests that, until the application has been laid open to public inspection (by the Danish Patent Office), or has been finally decided upon by the Danish Patent office without having been laid open to public inspection, the furnishing of a sample shall only be effected to an expert in the art. The request to this effect shall be filed by the applicant with the Danish Patent Office not later that at the time when the application is made available to the public under Sections 22 and 33(3) ofthe Danish Patents Act. If such a request has been filed by the applicant, any request made by a third party for the furnishing of a sample shall indicate the expert to be used. That expert may be any person entered on a list of recognized experts drawn up by the Danish Patent Office or any person by the applicant in the individual case. SWEDEN The applicant hereby requests that, until the application has been laid open to public inspection (by the Swedish Patent Office), or has been finally decided upon by the Swedish Patent Office without having been laid open to public inspection, the furnishing of a sample shall only be effected to an expert in the art. The request to this effect shall be filed by the applicant with the International Bureau before the expiration of 16 months from the priority date (preferably on the Form PCT/RO/134 reproduced in annex Z of Volume I ofthe PCT Applicant's Guide). If such a request has been filed by the applicant any request made by a third party for the furnishing of a sample shall indicate the expert to be used. That expert may be any person entered on a list of recognized experts drawn up by the Swedish Patent Office or any person approved by a applicant in the individual case. NETHERLANDS The applicant hereby requests that until the date of a grant of a Netherlands patent or until the date on which the application is refused or withdrawn or lapsed, the microorganism shall be made available as provided in the 31 F( 1 ) ofthe Patent Rules only by the issue of a sample to an expert. The request to this effect must be furnished by the applicant with the Netherlands Industrial Property Office before the date on which the application is made available to the public under Section 22C or Section 25 ofthe Patents Act ofthe Kingdom ofthe Netherlands, whichever ofthe two dates occurs earlier.

Claims: What Is Claimed Is: 1. An isolated nucleic acid molecule comprising a polynucleotide having a nucleotide sequence at least 95% identical to a sequence selected from the group consisting of: (a) a nucleotide sequence encoding the Brainiac-5 polypeptide having the amino acid sequence at positions 1-278 of SEQ ID NO:2; (b) a nucleotide sequence as encoded by the cDNA clone contained in the ATCC Deposit No. 203572; and (c) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b) or (c), above. 2. The nucleic acid molecule of claim 1 wherein said polynucleotide has the complete nucleotide sequence in Figures 1A and IB (SEQ ID NO: l). 3. The nucleic acid molecule of claim 1 wherein said polynucleotide has the nucleotide sequence in Figures 1A and IB (SEQ ID NO: l) encoding the Brainiac-5 polypeptide having the amino acid sequence in positions 1 to 278 of SEQ ID NO:2. 4. The nucleic acid molecule of claim 1 wherein said polynucleotide has the nucleotide sequence in Figure 1 (SEQ ID NO:l) encoding the Brainiac-5 polypeptide having the amino acid sequence from about 8 to about 278 in SEQ ID NO:2. 5. An isolated nucleic acid molecule comprising a polynucleotide having a nucleotide sequence at least 95% identical to a sequence selected from the group consisting of: (a) a nucleotide sequence encoding a polypeptide comprising the amino acid sequence of residues n'-278 of SEQ ID NO:2, where n 1 is an integer in the range of 1 to 8; (b) a nucleotide sequence encoding a polypeptide comprising the amino acid sequence of residues 1-m 1 of SEQ ID NO:2, where m 1 is an integer in the range of 263 to 278; (c) a nucleotide sequence encoding a polypeptide having the amino acid sequence consisting of residues n'-m 1 of SEQ ID NO:2, where n ! and m 1 are integers as defined respectively in (a) and (b) above; and (d) a nucleotide sequence encoding a polypeptide consisting of a portion of the Brainiac-5 amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572 wherein said portion excludes from 1 to about 8 amino acids from the amino terminus of said complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; (e) a nucleotide sequence encoding a polypeptide consisting of a portion of the Brainiac-5 amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572 wherein said portion excludes from 1 to about 15 amino acids from the carboxy terminus of said complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; and (f) a nucleotide sequence encoding a polypeptide consisting of a portion of the Brainiac-5 amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572 wherein said portion include a combination of any of the amino terminal and carboxy terminal deletions in (d) and (e), above. 6. The nucleic acid molecule of claim 1 wherein said polynucleotide has the complete nucleotide sequence of the cDNA clone contained in ATCC Deposit No. 203572. 7. The nucleic acid molecule of claim 1 wherein said polynucleotide has the nucleotide sequence encoding the Brainiac-5 polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572. 8. The nucleic acid molecule of claim 1 wherein said polynucleotide has the nucleotide sequence encoding the active polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572. 9. An isolated nucleic acid molecule comprising a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide having a nucleotide sequence identical to a nucleotide sequence in (a), (b) or (c) of claim 1 wherein said polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues. 10. An isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a Brainiac-5 polypeptide having an amino acid sequence in (a) or (b) of claim 1. 11. The isolated nucleic acid molecule of claim 10, which encodes an epitope-bearing portion of a Brainiac-5 polypeptide wherein the amino acid sequence of said portion is selected from the group of sequences in SEQ ID NO:2 consisting of: from about Val-1 to about Val-11; from about Thr- 14 to about Gln-22; from about Val-34 to about His-53; from about Phe-94 to about Val- 108; from about Ala- 120 to about Gln-126; from about Arg-138 to about Ile-149; from about Leu-202 to about Ala-211; and from about Phe-274 to about Ser-278. 12. A method for making a recombinant vector comprising inserting an isolated nucleic acid molecule of claim 1 into a vector. 13. A recombinant vector produced by the method of claim 12. 14. A method of making a recombinant host cell comprising introducing the recombinant vector of claim 13 into a host cell. 15. A recombinant host cell produced by the method of claim 14. 16. A recombinant method for producing a Brainiac-5 polypeptide, comprising culturing the recombinant host cell of claim 15 under conditions such that said polypeptide is expressed and recovering said polypeptide. 17. An isolated Brainiac-5 polypeptide comprising an amino acid sequence at least 95% identical to a sequence selected from the group consisting of: (a) the amino acid sequence positions 1 to 278 of SEQ ID NO:2 or the complete Brainiac-5 amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 203572; and (b) the amino acid sequence of the Brainiac-5 polypeptide having the amino acid sequence at positions 8 to 278 in SEQ ID NO:2, or as encoded by the cDNA clone contained in the ATCC Deposit No. 203572. 18. An isolated polypeptide comprising an epitope-bearing portion of the Brainiac-5 polypeptide, wherein said portion is selected from the group consisting of: a polypeptide comprising amino acid residues from about Val-1 to about Val-11 in SEQ ID NO:2; from about Thr- 14 to about Gln-22 in SEQ ID NO:2; from about Val-34 to about His-53 in SEQ ID NO:2; from about Phe-94 to about Val- 108 in SEQ ID NO:2; from about Ala-120 to about Gin- 126 in SEQ ID NO:2; from about Arg-138 to about Ile-149 in SEQ ID NO:2; from about Leu-202 to about Ala-211 in SEQ ID NO:2; and from about Phe-274 to about Ser-278 in SEQ ID NO:2 19. An isolated antibody that binds specifically to a Brainiac-5 polypeptide of claim 17. 21. An isolated polynucleotide encoding a modified Brainiac-5 polypeptide, wherein, except for at least one conservative amino acid substitution, said modified peptide has an amino acid sequence that is identical to amino acids 1 to 278 of SEQ ID NO:2. 22. A modified Brainiac-5 polypeptide, wherein, except for at least one conservative amino acid substitution, said modified polypeptide has an amino acid sequence that is identical to amino acids 1 to 278 of SEQ ID NO:2. 23. An isolated nucleic acid molecule comprising a polynucleotide having a sequence at least 95% identical to a sequence selected from the group consisting of: (a) the nucleotide sequence of SEQ ID NO:5; (b) the nucleotide sequence of SEQ ID NO:6; (c) the nucleotide sequence of SEQ ID NO:7; (d) the nucleotide sequence of SEQ ID NO:8; (e) the nucleotide sequence of SEQ ID NO:9; (f) the nucleotide sequence of SEQ ID NO: 10; (g) the nucleotide sequence of a portion of the sequence shown in Figure 1 (SEQ ID NO: l) wherein said portion comprises at least 50 contiguous nucleotides from nucleotide 1 to nucleotide 600; and (h) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b), (c), (d), (e), (f) or (g), above.

Inventors: RUBEN STEVEN M, YOUNG PAUL E, RUBEN, STEVEN, M., YOUNG, PAUL, E.
Applicants: HUMAN GENOME SCIENCES INC, RUBEN STEVEN M, YOUNG PAUL E, HUMAN GENOME SCIENCES, INC., RUBEN, STEVEN, M., YOUNG, PAUL, E.
Application year: 1999
Main classification: C07H
IPC codes: A61K31, A61K35, A61K38, A61K39, A61K45, A61K48, A61P1, A61P7, A61P19, A61P25, A61P29, A61P35, A61P37, C07K14, C07K16, C12N1, C12N5, C12N15, C12P21