ISOLATION, CHARACTERIZATION, AND USE OF THE HUMAN beta SUBUNIT OF THE HIGH AFFINITY RECEPTOR FOR IMMUNOGLOBULIN E

Abstract: The present invention relates to nucleic acid sequences encoding amino acid sequences of the alpha , beta , and gamma subunits of the high affinity receptor for immunoglobulin E, and for amino acid sequences of the subunits. The invention further relates to a method of producing the receptor by expressing cDNA for its alpha , beta , and gamma subunits in a host cell simultaneously. Aspects of the invention are methods and compositions to produce the human beta subunit, as well as to inhibit its function, thereby treating or preventing allergic reactions.

Description: , , OF THE HUMAN β SUBUNIT OF THE HIGH AFFINITY RECEPTOR FOR IMMUNOGLOBULIN E 5 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to DNA segments encoding the α, β, and 7 subunits of the high affinity receptor for immunoglobulin E (IgE) , in particular the 10 human β subunit. The invention further relates to a method of producing the receptor by expressing DNA encoding its α, β and 7 subunits in a host cell simultaneously. 2. Related Art 15 Receptors that bind the Fc region of immunoglobulins ("Fc receptors") mediate immunoglobulin transport across membranes, stimulate a variety of cellular activities induced by antigen-antibody complexes, and possibly regulate the biosynthesis of antibodies. Three of the 20 receptors (the receptor for polymeric immunoglobulin (Mostov et al. (1984) Nature (London) 308:37-43), the Fc receptors on macrophages and lymphocytes (Ravetch et al. (1986) Science 234:718-725), and the high affinity Fc, receptor on mast cells and basophils (Kinet et al. (1987) 25 Biochemistry 26:4605-4610; Shimizu et al. (1988) Proc. Natl. Acad. Sci. USA 85:1907-1911; Kochan et al. (1988) Nucleic Acids Res. 16:3584) share a common feature: their im unoglobulin-binding portion contains two or more immunoglobulin-like domains. 30 The high affinity IgE receptor Fc f RI is responsible for initiating the allergic response. Binding of allergen to receptor-bound IgE leads to cell activation and the release of mediators (such as histamine) responsible for the manifestations of allergy. This 35 receptor is a tetrameric complex aβ 2 which is found on the surface of mast cells and basophils. The o: and β su un s ave no een e ec e n o er ema opo cells although the 7 chains of FceRI are found in macrophages, NK cells and T cells where they associate with the low affinity receptor for IgG (FC7RIII) or with the T cell antigen receptor. The genes for α and 7, both have been localized on human (Le Coniat, 1990) and mouse chromosome 1. (Huppi, 1988; Kinet et al. 1987; Kochan et al. 1988; Shimizu et al. 1988; Ra et al. 1989.) The gene for mouse β has been localized on mouse chromosome 19 and is believed to be a single gene (Huppi, 1989) . The structures of the α gene in the rat (Tepler, 1989) and of the 7 gene (Kuster, 1990) , but not of the β gene have been characterized in the human. The receptor with high affinity for IgE Fc,RI is found exclusively on mast cells, basophils, Langerhans cells, and related cells. Aggregation of IgE occupied FcRI by antigen triggers both the release of preformed mediators such as hista ine and serotonin, as well as stimulation of the synthesis of leukotrienes. It is the release of these mediators that results in the allergic conditio . The most thoroughly characterized Fc t RI is that of the rat basophilic leukemia (FEL) cell line. It consists of three different subunits: (1) a 40-50 Kilodalton (Kd) glycoprotein alpha chain which contains the binding site for IgE, (2) a single 33 Kd beta chain and (3) two 7-9 Kd disulfide linked gamma chains (H. Metzger et al., Ann. Rev. Immunol. 4:419-470 (1986)). Complementary DNA (cDNA) for the rat α subunit has been isolated (J.-P. Kinet et al. , Biochemistry 26:4605- 4610 (1987)). However, previously there has been no disclosure of the isolation and characterization of the β and 7 subunits nor has it been possible to express IgE- binding by transfected cells (J.-P. Kinet et al. , Biochemistry 26:4605-4610 (1987); A. Shimizu et al. , Proc. Natl. Acad. Sci. USA 85:1907-1911 (1988)). Molecular cloning of some of the subunits in rodents and humans has permitted the reconstitution of surface . surprising findings from these studies was the differential requirement for surface expression among different species. Cotransfection of the three chains, , β and y is required to promote efficient surface expression of the rat (Blank, 1989) or mouse receptor (Ra, 1989) . By contrast, some surface expression of the human ay complex can be achieved by cotransfecting a and 7 alone in fibroblasts, suggesting that β may not be necessary (Miller, 1989) . This result and previous inability to clone the gene for the human β subunit raised the possibility that human beta might not exist and that 0:7 complexes might exist naturally in human cells. The high affinity IgE receptor Fc^I is a tetrameric hetero-oligomer composed of an α chain, a β chain and two disulfide-linked 7 chains (chains and subunits will be used interchangeably herein) . The β chain contains four transmembrane (TM) segments and long cytoplasmic domains which are thought to play an important role in intracellular signalling. It was very difficult to determine whether a human beta subunit even existed, and if so, to isolate its gene. The present invention has overcome these difficulties and surprisingly provided cDNA clones for the human β subunit of Fc,RI. The invention still further provides a method of producing the complete human Fc,RI receptor, and for inhibiting formation of the receptor or its function, by inhibiting the β subunit. SUMMARY OF THE INVENTION It is an aspect of this invention to provide nucleic acid segments encoding Fc,RI subunits. It is an aspect of this invention to provide nucleic acid sequences encoding the α, β, and 7 subunits of Fc r RI. In particular, this invention relates to DNA sequences. An aspect of the present invention is the complete human β gene and cDNA. Successful cloning of the human beta was not expected and was fraught with failures. Attempts to clone the human beta by simply using a rodent beta probe to screen various cDNA libraries failed to isolate a cDNA clone encoding human beta. Only a very short fragment (153 bp) with homology to rodent beta was isolated. However because this fragment may have been a portion of a beta-like molecule such as CD20, known to be homologous to beta in that region, PCR techniques were used to clone the human beta by using the information from the rodent beta sequence. However, although the homologies between human and rodent beta were 69% in the coding region, that was not sufficient for a PCR reaction. Human beta isolated by this method also failed. The existence of human beta was questioned because human beta was believed not necessary for expression of the alpha-gamma complex. Studies of gene transfer indicated that the transfer by transfection of the three genes for alpha, beta and gamma was necessary for the expression of the rat and mouse receptor. However, transfection of human alpha and gamma was sufficient to promote the surface expression of the human receptor in fibroblasts suggesting that the human beta was not necessary for the surface expression of the human receptor. That result raised the interesting question of the existence of human beta. Human beta was not necessary for the function of the alpha-gamma complex. Transfection of the cytoplasmic tail of gamma is sufficient for cell activation. Several groups made the observation that the cytoplasmic domain in the gamma chain was sufficient to mediate a number of biochemical signals leading to cell activation. These signals include tyrosine kinase activation, hydrolysis of phosphoinositides, calcium mobilization, production of IL2 in T cells, degranulation of mast cells and cell killing. It was demonstrated that the cytoplasmic domains of gamma contain a motif of 10-12 amino-acid . sufficient to trigger many different signals in different cells. It is transferable, and seemed to be interchangeable. Again these findings raised the question of the existence of human beta. If the gamma chain is sufficient for cell activation, perhaps there was no need for a beta. The inability to clone the human beta or even to detect transcripts for human beta in human cells (by using rat or mouse probes) also raised the question of the existence of human beta. Cloning required inventive methods and persistence. The 153 bp fragment used to screen further cDNA libraries did not work. However, assuming that the 153 bp could be part of human beta even though the homology was only about 70%, a 25 kb genomic clone was found. Smaller inserts were found which seemed to hybridize specifically with oligonucleotide probes corresponding with rat beta sequences. All these inserts (a total of 11 kb) were sequenced to reconstitute the different exons in the quest for those encoding human beta. Using what should be the beginning of the first exon and the end of the coding sequence in the seventh exon from the putative human beta gene, a putative cDNA human beta sequence was generated by PCR (by using first strand reverse transcripts from human basophils as templates for the PCR reaction.) It was demonstrated that the gene and cDNA isolated encoded human beta. The isolated gene and cDNA could correspond to a beta-like or CD20-like molecule which is homologous to rodent beta. However, the homology of 69% is not a criteria for the demonstration that these sequences encode human beta. Co-expression of alpha, beta and gamma in transfectants was preferred for the demonstration that the cDNA generated is indeed encoding human beta. However these experiments were not successful for the following reasons: . o- rans ec on o uman a a is sufficient for surface expression and functional reconstitution of the receptor on fibroblasts. 2. When human beta cDNA is co-transfeeted with alpha and gamma, the efficiency of transfection is not increased. In Fig. 20 the transfection of human alpha and gamma in COS-7 cells is shown to be sufficient for expression of the alpha-gamma complex on the surface of the transfectants. It also shows that human beta cannot replace rat beta in the expression of the rat IgE receptor. Therefore conditions were used where co- transfection of alpha and gamma does not work, to see if human beta could promote expression of the complete complex (Fig. 20) . This was done by truncation of the cytoplasmic tail of human gamma. In these conditions, co-transfection of human alpha with truncated human gamma does not result in the expression of the complex. However, co-transfection of human beta (but not of CD20) with alpha and trtincated gamma resulted in the expression of a functional complex capable of binding IgE. In these conditions, rat beta subunit cannot replace human beta subunit for expression of human alpha and truncated gamma subunits. This assay showed that human beta could associate specifically with the two other chains. Therefore, these new results demonstrate that human beta is a part of the human IgE receptor, and not merely a CD20-like molecule. These results reveal the previously unsuspected importance of human beta. In Fig. 21 transfection of alpha-gamma inKU812 cells showed very little expression of receptors. The level of expression is similar to the level obtained after transfection of beta and gamma. Therefore this level may be attributable to the endogenous alpha (for beta and gamma transfection) or to the endogenous beta (for alpha and gamma transfection) . By contrast the level of expression after co-transfection of the three cDNAs is very substantial. The conclusions are: . , regulates the level of expression of the receptor may be different than in fibroblasts. 2. In human mast cells and basophils, 5 receptor expression requires the presence of alpha, beta gene and gamma, whereas in transfected fibroblasts, human alpha and gamma are sufficient. t The human beta subunit gene spans approximately 10 kb and contains seven exons. There is a single 10 transcription initiation site preceded by a TATA box. The first exon codes for the 5' untranslated region and a portion of the N-terminal cytoplasmic tail. Transmembrane (TM) 1 is encoded in exon 2 and 3, TM 2 in exon 3 and 4, TM 3 in exon 5 and TM 4 in exon 6. The 15 seventh and final exon encodes the end of the C-terminal cytoplasmic tail and the 3' untranslated sequence. The human β gene appears to be a single copy gene. Two corresponding transcripts, detected as a doublet around 3.9 kb, are present in cells of mast cell and 20 basophil lineage from different individuals but not in the other hematopoietic cells tested. The human β protein is homologous to rodent β . The consensus amino acid sequences for human, mouse and rat β show 69% identical residues. 25 It is a further aspect of the invention to provide polypeptides corresponding to the a, 5, and 7 subunits of Fc < RI, more particularly to the human β subunit isolated from its natural environment. This may be defined to include the amino acid sequences of the polypeptides 30 either produced by recombinant methods, or synthesized by apparatus known to those of skill in the art, or isolated and purified by protein isolation and purification methods. The polypeptides comprise the entire amino acid sequence, or selected portions thereof, for example, 35 portions (domains) of the human beta subunit that are essential for (1) assembly of the receptor; (2) cell activation, and/or (3) complexing with the alpha and gamma subunits. "Natural environment" may be defined to include the subunits in the cells in which they naturally occur, n e orm an w o er ypes o pro e ns cellular components generally in structural or functional association with the subunits. It is another aspect of the invention to provide a recombinant DNA molecule comprising a vector and a DNA segment encoding the a, β, or 7 subunits of Fc f RI. It is a further aspect of the invention to provide a cell that contains the above-described recombinant DNA molecule. It is another object of the invention to provide a method of producing polypeptides having amino acid sequences corresponding to the a r B> r and 7 subunits of FC j RI, both in rodent and human species. Analysis of the surface expression of transfected receptors in fibroblast-like cells indicates that human α_7 and α37 complexes are expressed with comparable efficiency. Unexpectedly, assembly rules were different in other human cells. In addition, human β interacts with human α more efficiently than does rat β . By contrast, both rat and mouse β interact with their corresponding α chains much more efficiently than does human β , demonstrating a strong species specificity of the a-β interaction. It is a further object of the invention to provide a method of producing a functional Fc < RI receptor. In one embodiment, the present invention relates to DNA segments that code for polypeptides having amino acid sequences corresponding to the α, β, and 7 subunits of Fc ^ RI. In another embodiment, the present invention relates to polypeptides having amino acid sequences corresponding to the α, β, and 7 subunits of Fc c RI. In a further embodiment, the present invention relates to recombinant DNA molecules comprising a vector and a DNA segment that codes for a polypeptide having an amino acid sequence corresponding to the α, β or 7 subunits of Fc^I. r , relates to a cell that contains the above-described recombinant DNA molecule. In a further embodiment, the present invention relates to a method of producing polypeptides having amino acid sequences corresponding to the α, β, and y subunits of FCERI. In another embodiment, the present invention relates to a method of producing a functional FCERI receptor comprising introducing into a host cell DNA segments encoding the a , β, and 7 subunits of Fc,RI; and effecting expression of said DNA segments under conditions such that said receptor is formed. Expression of the receptor on the surface of cells COS-7 or CHO is achieved by the present invention when the cDNA for all three subunits of FCERI are simultaneously cotransfected. This success in expression of IgE binding permits detailed analysis of the IgE-receptor interaction and thus enables the development of therapeutically effective inhibitors. An aspect of the invention is to stem the cascade of allergic responses resulting from aggregation of the high affinity receptor for IgE, by inhibiting the essential participation of the human beta subunit. The beta subunit is the target to inhibit receptor aggregation and/or the function of the translate signal. Such an inhibition has widespread applications for prevention and treatment of allergic diseases because the undesirable events cascading from the receptor-IgE interaction are allergen independent and arise from various cell types: mast cells, basophils, Langerhans cells and the like. Inhibitors of beta include chemical preparations that attack the structure or function of the chain, anti-sense nucleic acid sequences, amino acid sequences capable of binding to the beta subunit polypeptide, and monoclonal antibodies directed to the subunit. Effective amounts of the beta subunit inhibitors will be determined after in vitro cell assays, assays in animal models, and clinical trials. ect ve amoun s of t e n ors w e com ne with a pharmaceutically acceptable carrier. Because of the variety of cell types in which the allergic response is related to the FC j RI, and because the reaction is allergen independent, route of administration may be either systemic or atopic. Candidate inhibitor substances are tested by methods disclosed herein. In vitro assays for inhibitor substances are provided through host cells transfected with nucleic acid sequences for encoding the human alpha, beta and gamma subunits, complexed or incubated with inhibitors * Cell activation effected by the Fc^I receptor is triggered and compared in the presence versus absence of inhibitors. Many assays are available. Further objects and advantages of the present invention will be clear from the following description and examples. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1. The nucleotide sequence (SEQ ID NO:10) and predicted amino acid sequence (SEQ ID NO:11) of human Fc^I alpha cDNA are shown. FIG. 2. The amino acid sequence homology of rat Fc^I alpha subunit (R) (SEQ ID NO:12), human Fc f RI alpha subunit (A) (SEQ ID NO:13) , and mouse Fc < RI alpha subunit (M) (SEQ ID NO:14) are shown. The regions of identity between the three are boxed. The number one position corresponds to the site of the predicted mature N- terminus of each protein. FIG. 3. A flow chart showing the construction of eukaryotic expression vectors which direct the synthesis of a complete biologically active FC j RI alpha chain (pHAI, pHAII) or a soluble, secreted, biologically active Fc < RI alpha chain (pHASI, pHASII) is presented. The sequence shown in this Figure is also disclosed in SEQ ID NO:20. . . prokaryotic expression vector which direcrs the synthesis of a soluble biologically active Fc ^ RI alpha chain (which consists of amino acid residues 26-204) is presented. The sequences shown in the pEVA construct are also shown in SEQ ID NOs. 15-17; the sequences shown in the pEVHA construct are also shown in SEQ ID NOs. 18 and 19; the sequences shown in the pEVHAS construct are also shown in SEQ ID NOs. 20 and 21. FIG. 5. Restriction maps for β cDNAs and strategy by which they were sequenced. The open rectangle indicates the sequence predicted to code for the β subunit; the lines indicate the 5 1 and 3 1 untranslated regions. The upper scheme shows the 1.5 kilobase (kb) clone containing a Pst I cleavage site. The lower scheme shows a 2.4-kb clone containing a Clal cleavage site. The 3' region of the latter has been truncated as indicated by the slashes. Its untranslated portion was sequenced as completely as the rest of the clone. Restriction sites are indicated by vertical bars: Hf, Hinfl; Hh, Hha J; Al, Alu I; Hp, HphI; Av, Ava II; Ac, Ace I; Ec, EcoRl; Hd, Hindlll . The horizontal arrows show the direction and extent of sequencing by the dideoxynucleoride chain-termination method. FIG. 6. (A) Nucleotide (SEQ ID NO:22) and deduced amino acid (SEQ ID NO:23) sequences of the cDNA coding for the β subunit. Beginning at the arrowhead (r) , an alternative sequence (B) was observed in six clones. The putative transmembrane domains are underlined. The tryptic peptides of the β subunit, from which the amino acid sequences were determined directly, are bracked (<>) . A putative poly (A) signal near the end is underlined. (B) Continuation of the nucleotide sequence (SEQ ID N0:24) of the deleted form of β cDNA, 3' to the junction indicated in A (T) . FIG. 7. Expression of cDNA coding for the β subunit. (A) Comparison of in vivo and in vitro translation products. RBL cells were grown in [ 35 S]cysteine containing medium. The detergent extract of the cells was prec p a e w m an , a er v gor , extracted with sample buffer and electrophoresed (lane 1) . This experiment employed concentrations of detergent high enough to dissociate the receptor completely. A transcript from the β cDNA was treated in vitro in [ 35 S]methionine-containing medium (lanes 2, 3, and 5). A control incubation contained no cDNA (lane 4) . The mixtures were allowed to react with monoclonal antibodies to the β subunit after a clearing immunoprecipitation. The specific washed precipitates were dissolved in sample buffer and electrophoresed: lanes 2 and 4, mAbβ(JRK) ; lane 3, mAbfl(NB) ; lane 5, irrelevant monoclonal antibody [mAbβ(LB) ] . An autoradiograph of the 12.5% polyacrylamide gel on which the specimens were analyzed under reducing conditions is shown. (B) Localization of one epitome to the NH 2 -terminal peptide of the β subunit. A β cDNA-containing vector was digested with Hhal before transcription using T7 polymerase. The resulting mRNA was translated to generate an NH 2 -terminal peptide of the β subunit β(amino acid 1-21) labeled with [ 35 S]methionine. The mixture was allowed to react with mAbβ(JRK) (lane 1) and the irrelevant mAb(LB) (lane 2) . The precipitates were analyzed on a 17% gel under nonreducing conditions. (C) Expression by E. coli of a COOH-terminal fragment of the β subunit. A Hinfl fragment, containing nucleotides 499-787, was subcloned into an E. coli expression vector (Crowl et al. (1985) Gene 38:31-38) and extracts were prepared. The proteins were electrophoresed as in A and transferred to nitrocellulose paper. The latter was allowed to react sequentially with monoclonal antibody mAbβ(NB) , developed with alkaline phosphatase-conjugated goat anti-mouse IgG (Fc) , and developed in the usual way (Rivera et al. (1988) Mol. Immunol.) . An enlargement of the lower half of the immunoblot is shown. Lane l, extract from transformant without insert; lane 2, extract from transformant with insert in wrong direction; lane 3, extract from transformant with insert correctly oriented. (D) Reactivity of β subunits with polyclonal antibodies induced by E. coli-expressed Hinfl fragments. Purified g - e e or comp exes ere e ec rop ore e , to nitrocellulose paper, and allowed to react with antibodies and subsequently with an appropriate alkaline phosphatase-conjugatedanti-immunoglobulinantibody. Lane 1, Abβ(JRK) ; lane 2, Abβ(NB); lane 3, immune serum to fragment A; lane 5, immune serum to fragment B; lanes 4 and 6, preimmune sera corresponding to the immune sera in lanes 3 and 5, respectively; lanes 7 and 8, second antibody only. This gel was run without molecular weight standards. FIG. 8. Hydropathicity plot of predicted sequence for the β subunit. The procedure and hydropathicity scale recommended by Engleman et al. (Engelman et al. (1986) Annu. Rev. Biophys. Biophys. Chem. 15:321-353) was used. The net hydropathicity value for the 20 amino acids for each successive "window" is plotted at the position corresponding to the 10th residue. A net free energy of >20 kcal (1 cal=4.18 J) for transfer to water suggests a transmembrane segment (Engelman et al. (1986) Annu. Rev. Biophys. Biophys. Chem. 15:321-353). FIG. 9. Nucleotide sequence (SEQ ID NO:26) of the 7 subunit of rat Fc,RI and the amino acid sequence (SEQ ID NO:27) that it predicts. The putative transmembrane domain is underlined. Amino acid resides are numbered starting with the first residue of the mature protein. Residues 5• to residue 1 have negative numbers and include the residues encoding a putative signal peptide according to the criteria of G. von Heijne (Nucleic Acids Res. 14:4683-4690 (1986)). The N-terminal and C-terminal cleavage sites are indicated by an arrow. The four tryptic peptides which were covered and sequenced are bracketed. An asterisk denotes an ambiguous residue in the sequence of the first tryptic peptide. FIG. 10. Hydropathicity plot of predicted sequences of FC.RI α subunit (panel A) , β subunit (panel B) and 7 subunit (panel C) . The hydropathicity scale is according to Engelman et al. (Ann. Rev. Biophys. Biophys. Chem. 15:321-353 (1986)) . The summed hydropathicity values for e am no ac s n success ve w n ows s p the position corresponding to the tenth residue. FIG. 11. Formation of IgE rosettes by transfected COS 7 cells and RBL cells. COS 7 cells were cotransfected with the coding portions of a , β and y cDNAs and sensitized with mouse IgE anti-DNP before being exposed to red cells derivatized with TNP (Panel A) . As a positive control, RBL cells were similarly tested for rosette formation (Panel C) . The specificity of the rosetting assay was assessed by preincubating the cotransfected COS 7 cells (Panel B) and RBL cells (Panel D) with rat IgE (which lacks the anti-DNP activity) prior to the addition of the mouse anti-DNP IgE. FIG. 12. Model of the tetrameric high affinity receptor for IgE. The polypeptides (SEQ ID NOs. 28-30) are shown in their fully processed form. The receptor is oriented such that the large extracellular portion of the α subunit is shown at the top and the remainder of the chain on the left. To the right of the a subunit (SEQ ID NO:28) is the β subunit (SEQ ID NO:29) with its four transmembrane segments and to the right of it, the dimer of 7 chains (SEQ ID NO:30) . Cysteines 26 and 68 and cysteines 107 and 151 in the α chain are paired as they are likely to be disulfide linked, as are the homologous cysteines in the FC7 receptors (M. Hibbs et al, J. Immunol.140:544-550 (1988) ) . The putative transmembrane segments have all been shown as consisting of 21 residues and would be expected to be in an α-helical conformation. The single letter code for amino acids is used (M. Dayhoff et al.. in Atlas of Protein Sequence and Structure, Suppl. 3, ed. M. Dayhoff, 363-373, Natl. Biomed. Res. Fndtn. , Washington D.C. (1978)). Every 10th residue (starting from the N-terminus) is shaded. FIG. 13. Restriction map structure of the human B gene and exon-intron are shown. The positions of the 7 exons are depicted by boxes. The location of the start and stop codon is indicated. FIG. 14. Nucleotide sequence (SEQ ID NO:31) of the human FcεRI β chain gene. The 7 exons are shown in bold. e ng o nuc eo es s re codon. The TATAA box, translation initiation codon (ATG) , termination codon (TAA) and the potential polyadenylation signals (AATAAA) are underlined. Bases which not determined with certainty are denoted as N. FIG. 15. Comparison of the human β gene and rat β cDNA sequences by a dot matrix blot. The Pustell DNA Matrix of the Macvector program was used with a window of 30 nucleotides and a minimum score of 63%. The Roman numerals indicated on the left correspond to the seven exons. FIG. 16. Presence of transcripts in basophils are shown. Ten micrograms of total RNA from basophil enriched leukocytes and various other cells were fractionated on a denaturing agarose gel before being transferred to Nytran membranes and hybridized with human β cDNA probes (nucleotides +306 to +456 for Panel A and nucleotides -2 to + 790 in Panel C) . The membrane shown in Panel A was stripped and rehybridized with a full length human a cDNA probe (Panel B) . FIG. 17. Determination of the transcription initiation site. Panel A: RNA from basophils was reverse transcribed, poly A+ tailed at both ends with terminal transferase and amplified with PCR. The amplified product (cDNA) and the genomic DNA (gene) were sequenced with an identical primer and the respective sequencing reactions were run in parallel on a 8% acrylamide gel. The arrow marks the transcription start site. Panel B: RNA from basophils (lane 1) or tRNA (lane 2) were used in the primer extension and the extended products analyzed on a 5% polyacrylamide urea gel in parallel with the sequencing reactions of the genomic DNA. The arrow marks the transcription start site. FIG. 18. Southern blot analysis of genomic DNA obtained from five different individuals. The DNAs were subjected to distinct restriction endonuclease digestions, blotted and hybridized with the human full length cDNA for the beta subunit. The numbers on the top n ca e e erent n v ua s w e eac pa corresponds to a different restriction digest. Size standards are indicated on the right. FIG. 19. Amino acid sequence of the FcsRI human β subunit (SEQ ID NO:32) and alignment with rat (SEQ ID NO:33) and mouse (SEQ ID NO:34) β . Identical and non- identical amino acid residues are indicated by capital and lower case letters respectively. The identities and closely related exchanges are marked Λ in the query line while the distantly related exchanges are denoted by a dot. Non-homologous exchanges show no marking in the query line. The gaps are indicated by a hyphen. The transmembrane domains are underlined and the splice sites indicated with vertical bars. FIG. 20. Results of FACS analysis showing IgE binding in COS-7 cells transfected with various combinations of Fcβl subunits. FIG. 21. Results of FACS analysis showing IgE binding in cells of a basophil line (KU812) transfected with various combinations of Fc^I subunits. DETAILED DESCRIPTION OF THE INVENTION The present invention relates, in part, to DNA sequences which code for polypeptides corresponding to the subunits of human FC.RI. More specifically, the present invention relates to DNA segments (for example, cDNA molecules) coding for polypeptides having amino acid sequences corresponding to the cr,β and 7 subunits of Fc e RI. In one embodiment, the DNA segments have the sequence shown in FIG. 1, 6, 9, or 14 (SEQ ID NOs. 10, 22 and 24, 26 and 31), allelic or species variation thereof, or a unique portion of such a sequence (unique portion being defined herein as at least 15-18 bases) . In another embodiment, the DNA segments encode the amino acid sequence shown in FIG. 1 (SEQ ID NOtll), 6 (SEQ ID NOs. 23 and 24), 9 (SEQ ID N0:27), or 19 (SEQ ID NOs. 32-34) , or allelic or species variation o , or a un que por on o s portion being defined herein as at least 5-6 amino acids) . Allelic or species variations are defined as substitutions, deletions, or other alterations in the nucleotide or amino acid sequence that do not eliminate the function of the subunits as defined herein. For some uses, the nucleotide sequence may be deliberately altered to, e.g., test the effects of such alteration on the function of the beta subunit, or to produce subunits which are inactiviated for certain purposes. In another embodiment, the present invention relates to polypeptides having amino acid sequences corresponding to the α,β and y subunits of Fc,RI. In one preferred embodiment, the polypeptides have amino acid sequences as shown in FIG. 1, 6, 9, and 19 (SEQ ID NOs. 11, 23 and 24, 27 and 32-34, respectively) or allelic or species variations thereof, or a unique portion of such sequences (unique portion being defined herein as at least 5-6 amino acids) . In another embodiment, the present invention relates to a recombinant DNA molecule comprising a vector (for example - plasmid or viral vector) and a DNA segment coding for a polypeptide corresponding to the α,β or y subunit of Fc,RI, as described above. In a preferred embodiment, the encoding segment is present in the vector operably linked to a promoter. In a further embodiment, the present invention relates to a cell containing the above described recombinant DNA molecule. Suitable host cells include procaryotes (such as bacteria, including Ej_ coli) and both lower eucaryotes (for example yeast) and higher eucaryotes (for example, mammalian cells) . Introduction of the recombinant molecule into the host cell can be effected using methods known in the art. In another embodiment, the present invention relates to a method of producing the above described polypeptides, comprising culturing the above described os ce s un er con ons suc a sa po ypep produced, and isolating said polypeptide. In a further embodiment, the present invention relates to a method of producing a functional Fc ^ RI receptor comprising introducing into a host cell DNA segments encoding the α,β and y subunits of Fc f RI and effecting expression of said segments under conditions such that said receptor is formed. Thenucleic acid sequences and polypeptides according to this invention exhibit a number of utilities including but not limited to: 1. Utilizing the polypeptide or a fragment thereof as an antagonist to prevent allergic response, or as a reagent in a drug screening assay. 2. Utilizing the polypeptide as a therapeutic agent. 3. Utilizing the polypeptide for monitoring IgE levels in patients. 4. Utilizing the nucleic acid sequence to synthesize polypeptides which will be used for the above purposes. 5. Utilizing the nucleic acid sequences to synthesize cDNA sequences to construct DNA useful in diagnostic assays. The present invention will be illustrated in further detail in the following examples. These examples are included for illustrative purposes and should not be considered to limit the present invention. EXAMPLE 1 Isolation of cDNA Clones for the Alpha Subunit of Human Fc f RI RNA was extracted from FUB12 cells as described by Kishi, Leukemia Research. 9,381 (1985) by the guanidium isothiocyanate procedure of Chirgwin, et al.. Biochemistry, 18,5294 (1979) and poly(A) mRNA was isolated by oligo-dt chromatography according to the methods of Aviv, et al.. P.N.A.S. U.S.A. , 69,1408 (1972) . Kinet, et al.. Biochemistry, 26,2569 (1987). The resulting cDNA molecules were ligated to EcoRl linkers, digested with the restriction enzyme EcoRl, size fractioned and ligated to λgtll EcoRl arms as set forth in Young et al.. Science. 222.778 (1983) . The cDNA insert containing λgtll DNA was packaged into bacteriophage lambda particles and amplified on Y1090. A total of 1.2x106 independent cDNA clones were obtained. The cDNA library was plated onto Y1090 on 150 mm 2 plates (10 5 per plate) and transferred to nitrocellulase filters. The cDNA library filters were screened by in situ hybridization using a nick translated cDNA fragment as in Kochan, et al. , Cell. 44,689 (1986). The cDNA fragment was obtained from the rat Fc,RI alpha cDNA corresponding to nucleotides 119-781. Positive plaques were identified, purified and the cDNA inserts were subcloned, using standard techniques, into the pGEM vectors (Promega Biotech, Madison, Wisconsin) . The cDNA insert was mapped by restriction enzyme analysis, subcloned into derivatives of pGEM and sequenced using the dideoxynucleotide method of Sanger et al.. P.N.A.S.. 74,5463 (1977; following the GemSeq double strand DNA sequencing system protocol from Promega Biotech (Madison, Wisconsin) . The DNA sequence was determined for both strands of the cDNA clone pLJ663 (nucleotides 1-1151) and for 300 bp of each end of clone pLJ 587 (nucleotides 658- 1198) . No discrepancy in DNA sequence between the two cDNA clones was observed. The sequence for the human Fc t RI alpha cDNA is presented in FIG. 1 and SEQ ID NO:10. The predicted amino acid sequence for the human Fc,RI alpha polypeptide is shown below the nucleotide sequence and in SEQ ID NO:11, beginning with methionine at nucleotide 107-109 and ending with asparagine at nucleotide 875-877. The site of the predicted mature N-terminus was determined to be valine at nucleotide 182-184 according to the rules set forth by von Heijne, Eur. Journal of Biochem 137.17: and Nucleic Acid Research. 14,4683 (1986). ese resu s pre c a am no ac s gna . The rest of the cDNA sequence suggests that the human Fc £ RI alpha chain contains about 179-224 residues with 2 homologous domains (14 out of 25 residues are identical; residues 80-104 and 163-190) , a 20-residue transmembrane segment (residues 205-224) and a 33 residue cytoplasmic domain containing 8 basic amino acids. Overall, there is 47% identity between the human and rat FcRI alpha sequences, and 46% identity between the human FRl alpha and mouse FcGR alpha (FIG. 2 and SEQ ID NOs. 12-14) . The greatest level of homology is within the transmembrane region where 9 amino acids surrounding the common aspartic acid residue are identical. EXAMPLE 2 Expression of the Human Fc.RI Alpha Complete and Soluble Forms in Eukaryotic Cells Using the recombinant cDNA clone for the human Fc II alpha chain, it is possible to introduce these coding sequences into an appropriate eukaryotic expression vector to direct the synthesis of large amounts of both a complete and soluble form of the alpha chain. For surface expression it may necessary that the alpha subunit be complexed with the beta or gamma subunit whereas for the eukaryotic expression of the secreted form of the alpha subunit this may not necessary. An appropriate vector for the purpose is pBC12BI which has previously been described in Cullen, (1987) Methods in Enzvmoloσv 152. Academic Press, 684. Construction of expression vectors coding for the complete alpha chain can be isolated as follows (FIG. 3) : A unique Bqlll-Sspl fragment (nucleotides 65-898) is isolated from pLJ663, the Bglll end is filled in with DNA polymerase I Klenow fragment and ligated into pBC12BI which has been restricted with either Hindlll-BamHI or Hindlll-Smal (the ends are made blunt by filling in with DNA polymerase I Klenow fragment) . The reason for attempting two different constructions is that the former contains . absence of introns may affect the levels of the alpha protein which are synthesized in cells transfected by these vectors. Construction of expression vectors coding for the soluble form of the alpha chain would be accomplished by introducing a termination codon at nucleotides 719-721 of the coding region in the alpha chain of the expression vectors noted above (pHAI, pHAII, FIG. 3) . This would remove the putative transmembrane and cytoplasmic regions resulting in the synthesis of a secreted soluble form of the human alpha chain. Introduction of a termination codon is accomplished by oligonucleotide-directed site specific mutagenesis as outlined by Morinaga et al.. Bio. Tech., 2, 636 (1984). The sequence of the oligonucleotide will be 5' AAGTACTGGCTATGATTTTTTATCCCATTG 3' (SEQ ID NO:l). The resulting expression vectors are pHASI and pHASII (FIG. 3) and these will direct the synthesis of a truncated alpha protein corresponding to amino acids 1-204. Expression of this protein in eukaryotic cells will result in synthesis of a mature, IgE binding protein encompassing amino acid residues 26-204. The expression vectors are then introduced into suitable eukaryotic cells such as CHO or COS by standard techniques such as those set forth in Cullen, (1987) , Methods in Enzvmoloσv. Academic Press, NY 152:684, in the presence of a selectable marker such as G418 or Methotrexate resistance. The selectable marker for Methotrexate resistance has an added advantage, since the levels of expression can be amplified by introducing the cells to higher levels of drugs. The synthesis of protein is monitored by demonstrating the ability of human IgE (or rat IgE) to bind to these cells (in the case of the complete alpha chain) , or in the case of the soluble form of the alpha chain, to demonstrate that the protein secreted from these cells has the ability to bind IgE in the presence or absence of the beta. Expression of the Human Fc r RI Alpha Soluble Form in Prokaryotic Cells Using the recombinant cDNA clone for the human Fc t RI alpha chain, it is possible to introduce these coding sequences into an appropriate prokaryotic expression vector to direct the synthesis of large amounts of a soluble (non-membrane bound) IgE binding polypeptide derived from the alpha chain. An appropriate vector for this purpose is pEV-1 which has been described by Crowl, et al.. Gene. 38, 31 (1985). Construction of an expression vector coding for a soluble alpha chain can be isolated as set forth in FIG. 4: a unique Mstll-Sspl fragment (nucleotides 195-898 is isolated from pLJ663, the Mstll end is filled in with DNA polymerase I Klenow fragment and ligated into pEV-1 which has been restricted with EcoRl, and the ends filled in with Klenow (FIG. 4, pEVA) . The N-terminus of the mature alpha chain is reconstructed by oligonucleotide directed-site specific mutagenesis. The sequence of the oligonucleotide will be 5 1 GAATTAATATGGTCCCTCAGAAACCTAAGGTCTCCTTG 3' (SEQ ID NO:2) . Introduction of this sequence into the expression vector pEVA aligns the Methionine residue of the EV-1 vector next to Valine-26 (the predicted mature N-terminus of the alpha chain) followed by amino acid residues 27- 204 (pEVHA, FIG. 4) . Reconstruction of the soluble form Fc II alpha is accomplished by oligonucleotide site- directed mutagenesis. The sequence of the o l i g o n u c l e o t i d e w i l l b e 5 • - AAGTACTGGCTATGATTTTTTATCCCATTG - 3' (SEQ ID NO:3). Introduction of this sequence into the expression vector, terminates polypeptide synthesis just prior to the start of the transmembrane region. The protein thus encoded by expression vector pEVHAS, should faithfully direct the synthesis of a soluble form of the alpha chain, corresponding to amino acid residues 26-204. This expression vector is then transformed into suitable hosts. Isolation and Sequence Analysis of Peptides of the Beta Subunit of Fc.RI Since repeated attempts to sequence intact β chains were unsuccessful, peptides were isolated from tryptic digests. Electroeluted β subunits from polyacrylamide gels were prepared as described (Alcaraz et al. (1987) Biochemistry 26:2569-2575) . Tryptic peptides were separated by high-pressure liquid chromatography and sequenced as before (Kinet et al. (1987) Biochemistry 26:4605-4610) . A peptide (no. 1) isolated from an initial digest had the sequence (SEQ ID NO:4) Tyr-Glu- Glu-Leu-His-Val-Tyr-Ser-Pro-Ile-Tyr-Ser-Ala-Leu-Glu-Asp- Thr. The same peptide from later digests showed an additional leucine at the NH 2 terminus and an arginine at the COOH terminus. The sequences of three other peptides, each isolated in substantial yields, are indicated in a subsequent figure. EXAMPLE 5 Cloning and Sequencing of cDNA clones of the Beta Subunit of Fc,RI RNA extracted from rat basophilic leukemia (RBL) cells by the guanidinium isothiocyanate method (Chirgwin et al. (1979) Biochemistry 18:5294-5299) was fractionated on an oligo(dT)- cellulose column (Maniatis et al. (1982) Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Lab. , Cold Spring Harbor, NY) and used to construct a pUC-9 and a λgtll library (Maniatis et al. (1982) Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Lab. , Cold Spring Harbor, NY; Young and Davies (1983) Proc. Natl. Acad. Sci. USA 80:1194-1198). The initial sequence obtained for peptide l was used to construct two 26-mer oligonucleotides of 32-fold degeneracy: 5' -GGIGA(A/G) TA(G/C) ACATGIA(A/G) (C/T) TC (C/T) TCATA-3' (SEQ ID NO:5) and 5«- GGICT(A/G)TA(G/C)ACATGIA(A/G) (C/T)TC(C/T)TCATA 3 1 (SEQ ID NO:6). A λgtll library constructed from mRNA of RBL oligonucleotides. Colonies were screened as in Kinet e£ al. (1987) Biochemistry 26:4605-4610, using oligonucleotides prepared on a model 380A automated DNA synthesizer (Applied Biosystems, Foster City, CA) . Six positive clones gave similar restriction patterns. cDNA inserts were subcloned into pGEM-4 or pGEM-3Z and the resulting double-stranded DNA was sequenced with the GemseqRT sequencing system according to the method recommended by the supplier (Promega Biotec, Madison, WI) . Twenty-mer oligonucleotides, corresponding to previously sequenced regions by this method, were used as lprimers to generate overlapping sequences otherwise difficult to obtain. In some instances, DNA sequencing was performed using Sequenase as recommended by the supplier (United States Biochemical, Cleveland) . The clone containing the longest insert was sequenced according to the strategy shown in the upper portion of FIG. 5. The sequence predicts possible starting codons at nucleotides 46-48 and 55-57, which would yield a polypeptide of 246 or 243 residues, respectively (FIG. 6A and SEQ ID NO:22) . The predicted M,. of about 27,000 is some 20% less than the apparent molecular weight of β subunits when analyzed on polyacrylamide gels (Holowka and Metzger (1982) Mol. Immunol. 19:219-227). In addition, no in-frame stop codon was apparent upstream of the start codon. To rule out the possibility that the true start codon was still further 5* , the cDNA library was rescreened with a restriction fragment (nucleotides 7-474) and with a synthetic oligonucleotide probe (nucleotides 3-32). Twenty-eight additional clones were isolated and their restriction patterns were examined. Twenty were similar to the original clones. Only six additional nucleotides at the 5 1 end (nucleotides 1-6, FIG. 6A were identified. Early termination was found in six clones, which otherwise had the same sequence through nucleotide 375 (FIG. 6B and SEQ ID NO:24) . One 2.4-kb clone had cytidine 473 substituted with an adenine. This substitution abolishes the Pst I site and creates a new . , would become Asp-140 (FIG. 6A) . Finally, one clone extended «350 base pairs (bp) in the 5' direction. The junction with the sequence shown in FIG. 6A was (SEQ ID NO:7) AATAAAACAAAAAAAAAAAAATG, the last two nucleotides of the newly generated ATG corresponding to nucleotides 8 and 9 of the previous sequence. It is likely that this clone simply resulted from the ligation of two independent cDNAs. Screening of the pUC-9 library revealed three clones. However, the sequence of none of these extended 5' beyond nucleotide 84. EXAMPLE 6 RNA Transfer Blotting RNA transfer blotting was performed under high stringency using a Pst I fragment probe (nucleotides 1- 474) . Thirty micrograms of total RNA was run on a 1% agarose gel containing 2% formaldehyde and blotted to nitrocellulose filters (Maniatis et al. (1982) Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Lab., Cold Spring Harbor, NY) . The filters were hybridized with a restriction fragment of the β cDNA (nucleotides 1- 474) as described (Maniatis et al. (1982) Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Lab. , Cold Spring Harbor, NY) and washed with 15 mM NaCl/1.5 mM sodium citrate at 65°C. RBL cells yielded two major bands at κ2.7kb and 1.75kb with the upper band having about twice the intensity of the lower one. A minor band 1.2kb was also noted. Negative results were obtained with a variety of cells that do not express high-affinity IgE receptors: the rat pituitary line GH3 (American Type Culture Collection no. CCL82.1), the rat glial cell line C6 (no. CCL107) , the mouse Leydig cell line 1-10 (no. CCL83) , and, notably, the mouse monocytic line J774 (no. T1B67) and the rat lymphoma "NTD" (Rivera et al. (1988) Mol. Immunol.) EXAMPLE 7 In vitro transcription and translation cDNAs corresponding to the β subunit and various mutated or truncated forms thereof were subcloned into either pGEM-4 or pGEM-3Z transcript ion vectors (Promega Biotec) . The β clone containing the Pst I site was transcribed in vitro with T7 RNA polymerase. Unlabeled RNAs were synthesized using either SP6 or T7 polymerase as recommended by the supplier. Capping reactions were performed as reported (Contreras et al. (1982) Nucleic Acids Res. 10: 6353-6362) . After digestion of the template with RNase-free DNase I, the RNAs were purified further by extraction with phenol/chloroform and three precipitations from ethanol. The RNA was then translated with a micrococcal nuclease-treated lysate of rabbit reticulocytes in the presence of [S 35 ] methionine as recommended by the supplier (Promega Biotec) . The products of translation were diluted 1:1 with 20 mM detergent {3-[3-(cholamidopropyl)dimethylammonio]-1- propane sulfonate in borate-buffered saline (pH 8) containing 30 μl of aprotinin per ml, 175 μg of phenylmethyl-sulfonyl fluoride per ml, 10 μg of leupeptin per ml, and 5 μg of pepstatin per ml and immunoprecipitated with monoclonal antibodies as described (Rivera et al. (1988) Mol. Immunol.). The unfractiona ed translated material showed a major component at M,.32,000 compared to the control from which the RNA had been omitted or an alternative RNA (brome mosaic virus) had been substituted. The isolation of antibodies was as follows: Escherichia coli transformed with an expression vector containing the desired restriction fragments (Crowl et al. (1985) Gene 38:31-38; Portnoy et al. (1986) J. Biol. Chem. 261:14697-14703) were cultured and induced, and the fraction enriched for the recombinant protein was prepared as described (Portnoy et al. (1986) J. Biol. Chem. 261: 14697-14703). After separation on polyacrylamide gels in sodium dodecyl sulfate (NaDodS0 4 ) - immunize rabbits. Approximately 100 μg of protein was injected in complete Freund's adjuvant; this was followed by a booster injection of 25 μg of protein in incomplete adjuvant. The isolation and characterization of monoclonal anti-β antibodies mAbβ(JRX) and mAbβ(NB) (the latter, was obtained from David Halowka, Cornell University) have been described (Rivera et al. (1988) Mol. Immunol. 25:647-661). The monoclonal anti-β antibodies mAbβ(JRk) and mAbβ(NB) (Rivera et al. (1988) Mol. Immunol.) (FIG. 7A, lanes 2 and 3) - but not an irrelevant antibody (lane 5)- precipitated radioactive material, which on polyacrylamide gels in NaDodS0 4 showed a major band at » 32000. This band had the identical mobility as the upper band of the doublet precipitated by mAbβ(JRK) from an extract of labeled RBL cells (lane 1) . Although not seen well in the reproduction, the autoradiogram showed that the material synthesized in vitro also contained the lower molecular weight component seen the in vivo synthesized 0 chains. The mobility of the in vitro synthesized protein was unaltered by reduction as has been previously observed with the β subunit. The clone containing the Cla I site (which lacks the first ATG codon) led to the synthesis of a protein whose mobility on gels was indistinguishable from that for the clone containing the Pst I site. On the other hand, an aberrant clone containing the newly generated ATG (above) induced the synthesis of a somewhat larger protein with an apparent ,, of 33,500. In vitro translation of a transcript coding for the NH-terminal 21 amino acids of the β subunit led to a product precipitable by mAbβ(JRK) (FIG. 7B) . EXAMPLE 8 Expression of the Beta Subunit of Fc f RI in E . Coli Two Hinfl fragments (A, nucleotides 106-498; B, nucleotides 499-787) were individually subcloned into an . express on e or, r from the induced cultures. The results of one immunoblotting experiment are shown in FIG. 7C. The material extracted from the bacteria transformed with a vector containing the Hinfl fragment B exhibited a M r 14,000 component reactive with mAbβ(NB) but not with Abβ(JRK) (FIG. 7C, lane 3). The extract from the transformants containing the more NH 2 -terminal Hinfl fragment A (residues 17-148) reacted with neither antibody (compare with above) . Rabbit antibodies generated by fragment A reacted on i munoblots with purified receptors exactly at the position where the two monoclonal anti-β antibodies reacted (FIG.7D, lanes 1-3) and quantitatively precipitated intact I25 I-labeled IgE- receptor complex from unfractionated detergent extracts of RBL cells. EXAMPLE 9 Biosynthetic Incorporation Biosynthetic incorporation of labeled amino acids and monosaccharides was as described (Perez-Montfort et al. (1983) Biochemistry 27:5722-5728). The purification and analysis on gels and by immunoblotting of the IgE- receptor complexes have also been described (Rivera et al. (1988) Mol. Immunol.). By using biosynthetic incorporation of two different amino acids labeled distinguishably, their ratio in the subunits of the receptor (Table 1, right part) was determined. The ratios of four distinctive amino acids to each other was in satisfactory agreement with the ratios predicted from the β cDNA clone (Table l, right part, columns 1-3) . Because the cDNA for the β subunit predicts three potential glycosylation sites, a double- labelling experiment using ( 3 H] annose and ( 35 S)cysteine was also performed. Based on the relative carbohydrate data reported for the α subunit (Kaneilopoulos et al. (1980) J. Biol. Chem. 255:9060-9066) and correcting them on the basis of the peptide molecular weight for this , a subunit contains «20 mol of mannose per mol. It was therefore possible to determine the mannose/cysteine ratio in the β subunit from the double-labeling experiment. The results showed only 0.05 mol/mol of cysteine or 0.3 mol/mol of the β subunit (Table 1, right part, column 4) . TABLE I. Amino Acid compos it inn υf I) Subunits cDNA versus compositional analysis for the R subunit Hi l Ar Cy Trp s 6 s Dedυccd from 20 12 23 24 15 12 19 17 15 36 12 H cDNA Direct 22 13 22 27 13 19 18 14 13 3 1 10 lo ιυ ND analysis " Double- labeling studies * cDNA versus incorporation data Met Cys/H Cyi/T Man/C His is rp ys Deduced from ~ cDNA Direct analysis * Double- 4 2 5. 1 2.5 0.05 labeling studies* " The mol % of each mnino acid as reported by Alcaraz et a|. ((1987) Biochemistry 26:2569-2575) was multiplied by 241 the number of residues, excluding tryplophan - predicted from the cDNA. ND, not determined, 'IgE-rcceptor complexes were purified from RBL cells incubated with a mixture υf two precursors labeled with dilfereiiliul.lc radioisolopca. The subunits were icparated on • polyacrylamide gel, The gel was sectioned into 2-mm slices, extracted, and assayed for radioactivity by scintillation ipectroscopy, The ratio of cpm of M S/'H was individually calculated for a, 0, and γ subunits, The ratio in the a, subunit is proportional to the known molar ratio of the J5 S-labclcd and Η-labe|ed residues in the or subunit. Hence, the corresponding ratio in the fl subunit (and the γ subunit) predicts the ratio of the same residues in the latter subunits. Sequence Characteristics There is ample evidence that the cDNAs that were isolated code for the β subunit. (i) In vitro transcription of the cDNA and translation of the derived mRNA produce a protein whose apparent molecular weight on gel electrophoresis is indistinguishable from that of authentic β chains (FIG. 7A) . (ii) The cDNA accurately predicts the sequence of four peptides isolated from a tryptic digest of β chains (FIG. 6A and SEQ ID NO:22) and a composition that agrees well with direct analyses and biosynthetic incorporations (Table I) . (iii) Two monoclonal antibodies reactive with discrete epitopes on the β subunit (Rivera et al. (1988) Mol. Immunol.) precipitate the protein synthesized in vitro from the cloned cDNA (FIG. 7A) , and one of them reacts with a fragment of the protein expressed in E. coli (FIG. 7C) . (iv) Polyclonal antibodies raised against a fragment of the β subunit synthesized by E. coli transformants react with β chains on immunoblots (FIG. 7D) and with IgE- receptor complex in solution. The nucleotide sequence at the 5' end of the cloned cDNA (clone 1) does not in itself define the start of the open reading frame unambiguously. There is no leader sequence and no "in frame" stop codon preceding the presumptive start codon. In addition, the molecular weight deducted from the cDNA (M,."27,000) is substantially lower than the one observed on NaDodS0 4 gels (M r ~32,000), although the β subunit is not glycosylated. Therefore, it was possible that the start codon had been missed. Nevertheless, the aggregate data provide strong evidence that the full coding sequence for the β subunit has been recovered, (i) Extensive attempts failed to reveal cDNAs in either of two separate libraries with a more extended 5' sequence. (ii) The major species generated by 5' extension studies terminated precisely at the point at which most of our clones started, (iii) The second ATG codon at the 5' end mee s e consensus c arac er s cs o nown n a sites (Kozak (1987) Nucleic Acids Res. 15:8125-8148). That it is preceded by a nearby 5' ATG codon is uncommon, but not rare (Kozak (1987) Nucleic Acids Res. 15: 8125- 8148) , and has been observed for the human α subunit (Shimizu et al. (1988) Proc. Natl. Acad. Sci. USA 85:1907-1911; Kochan et al. (1988) Nucleic Acids Res. 16:3584) . (iv) As already noted, in vitro translation of an mRNA transcribed from the cDNA containing only the second ATG codon gives a polypeptide indistinguishable in length from the authentic β chains. An aberrant clone containing a start codon 48 nucleotides 5' to the presumed start codon directed the in vitro synthesis of a polypeptide with an apparent molecular weight appropriately greater than that of the β subunit. Therefore, the correspondence in apparent molecular weight between authentic β chains and the protein synthesized in vitro from clone 1 is meaningful. The RNA transfer blotting data show an mRNa of ~2.7Kb, precisely what would be anticipated from the cDNA that was sequenced (FIG. 6) , given a poly (A) tail of «200 nucleotides. In the discussion that follows it is assumed that the β chain begins with the methionine residue coded for by the second ATG and is, therefore, 243 residues long. Only a single clone containing the Cla I restriction site was observed among the 37 clones analyzed. This clone likely resulted from a single base mutation during the cloning and is unlikely to represent a normally occurring mRNA. Conversely, six clones showing the deleted sequence (FIG. 6B) were observed and likely reflected an authentic species of mRNA. If translated, it would code for a ^"14,000 protein with only a single transmembrane segment. The sequence of the β subunit contains potential sites for N-linked glycosylation at residues 5, 151, and 154. However, past and new incorporation data give no evidence for carbohydrate in the β subunit (Perez- Montfort et al. 1983) Biochemistry 27:5722- 5728; o ow a an e zger o . mmuno . : - ; a Table I) . The sequence shows no unusual features or homology to previously reported sequences, in particular to those associated with Fc receptors or with Fc binding factors. A hydropathicity analysis suggests that the β subunit crosses the plasma membrane four times (FIG. 8) . The hydrophilic NH 2 and COOH terminus would therefore be on the same side of the membrane. Expression of fragments of the β cDNA indicate that mAbβ-(NB) reacts within amino acids residues 149-243 (FIG. 7C) and that mAbβ(JRK) reacts with fragment containing residues 1-21 (FIG. 7B) . Because neither antibody reacts appreciably with intact cells but both react strongly with cell sonicates, the combined results are consistent with the NH 2 and COOH terminus being on the cytoplasmic side of the plasma membrane. Earlier studies had suggested that the β chain contained a M,"20,000 "β," domain resistant to proteolysis while membrane bound (Holowka and Metzger (1982) Mol. Immunol. 19:219-227). This portion also contained those residues that were modified by an intrabilayer labeling reagent (Holowka and Metzger. (1982) Mol. Immunol. 19:219-227; Holowka et al. (1981) Nature (London) 289:806-808) and became linked to the β and/or γ subunit when chemical crosslinking reagents were used (Holowka and Metzger (1982) Mol. Immunol. 19:219-227) and to the subunit when spontaneous disulfide linkage between the β and y 2 , subunits occurred (Kinet et al. (1983) Biochemistry 22:5729-5732) . The remainder, "β 2 ,", appeared to contain the serine residues that became phosphorylated in situ (Perez-Montfort et al. , (1983) Biochemistry 22:5733-5737; Quarto and Metzger (1986) Mol. Immunol. 23:1215-1223) but has never been positively identified as a discrete fragment. The sequence predicted by the cDNA for the β subunit suggests that part or all of either the NH 2 -terminal 59 residues or the COOH-terminal 44 residues, or of both, is cleaved off to generate the βl fragment. Contransfeetion Experiments The full-length coding sequences of the a and the β subunits were cotransfected in COS 7 cells by using a vector for transient expression. No IgE-binding sites were expressed at the surface of transfected cells. Studies of the receptor with low affinity for IgE on macrophages revealed a component that could be chemically crosslinked to the IgE-binding portion and that had an apparent molecular weight similar to the β subunit of the high-affinity receptor (Finoloom and Metzger (1983) J. Immunol. 130:1489-1491). The peptides generated from this component by protease digestion appeared to differ from those released from β subunits, but it raised the possibility that other Fc receptors also contained β-like subunits that had heretofore escaped detection (Rivera et al. (1988) Mol. Immunol.). Evidence for this from RNA transfer blot experiments conducted at high stringency is not available. In particular, J774 cells are known to contain FC receptors whose immunoglobul in-binding chain shows considerable homology to the a chain of the high- affinity receptor for IgE (Kinet et al. (1987) Biochemistry 26: 4605-4610) . However, it was not possible to detect mRNA for β chains by the methods that were employed. Similarly, NTD lymphoma cells gave negative results even though they have Fcγ receptors and show a low molecular weight component that reacts with Abβ(JRK) on immunoblots. EXAMPLE 12 Isolation and Sequence Analysis of Peptides of the Gamma Subunit of Fc.RI Fc^I was purified by affinity chromatography using TNP-lysirie beads as described in G. Alcaraz et al.. Biochemistry 26:2569-2575 (1987) . The eluate was applied to sepharose 4B beads coupled by cyanogen bromide to monoclonal anti-β (JRK) (J. Rivera et al.. Mol. Immunol. 25:647-661 (1988)). After washing the beads with 2 mM , material was eluted at 65°C with 0.1% sodium dodecyl sulfate, phosphate buffered saline, pH 6.5. The subunits from Fc,RI were then separated by HPLC size chromatography, the β and y containing fractions recovered, reduced, alkylated and digested with trypsin (J.-P. Kinet et al.. Biochemistry 26:4605-4610 (1987)). The resulting peptides were separated by HPLC reverse phase chromatography as in J.-P. Kinet et al, Biochemistry 26:4605-4610 (1987) . The chromatograms from the β and y digests were compared and the non-overlapping q peptides were sequenced (J.-P. Kinet et al. , Biochemistry 26: 4605-4610 (1987)). EXAMPLE 13 Cloning and Sequencing of cDNA clones of the Gamma Subunit of FC.RI Oligonucleotide probes were synthesized according to the sequences of peptide 3 (residues 41 to 47 of SEQ ID NO:27) and of peptide 4 (residues 54 to 62 of SEQ ID NO : 27 ) . Th e s e q u e n c e s w e r e GA(A/G)AA(A/G)TCIGA(T/C)GCTCTCTA (SEQ ID NO:8) and AA(T/C)CA(A/G) GA(A/G)ACITA(T/C)GA(A/G)ACI(T/C)TIAA (SEQ ID NO:9). The methods used to screen the λgtll library, to purify, subclone and sequence the positive clones are known in the art (J.P. Kinet et al.. Biochemistry 26:4605-4610 (1987)). Peptide 3 and peptide 4 were also synthesized using a peptide synthesizer ABI 431A. The purity of the synthetic peptides was assessed by HPLC reverse phase chromatography, amino acid composition and mass spectroscopy. The peptides were conjugated either to ovalbumin using m-Maleimidobenzoyl-N- hydroxysuccinimide ester (F.T. Liu et al.. Biochemistry 18:690-697 (1979)) at a molar ratio of 5:1 or to sepharose 4B with cyanogen bromide. Rabbits were immunized with the ovalbumin-conjugated peptides, the antisera collected and the antipeptide antibodies purified by affinity chromatography using sepharose 4B co uga e pep es. e an pep e an tested for reactivity with the y subunit of Fc c RI by Western blotting and for their ability to immunoprecipitate I25 I-IgE receptor complexes (J. Rivera et al. , Mol. Immunol. 25:647-661 (1988)) . The nucleotide sequence of the y subunit of rat Fc,RI (SEQ ID NO:26) obtained using the method of this invention, as well as the amino acid sequence (SEQ ID NO:27) that it predicts, are shown in FIG. 9. In order to isolate and characterize the cDNA for the y subunit, cDNAs for the Fc e RI y subunit were isolated from a λgtll library prepared from rat basophilic leukemia (RBL) cells (J.P. Kinet et al. , Biochemistry 26:4605-4610 (1987)) using oligonucleotide probes. Four peptide sequences were identified in a tryptic digest of the FC. I subunits, and two of the peptides were used to synthesize two oligonucleotide probes (FIG. 9) . The library was screened in duplicate with these two probes and overlapping plaques identified. Three discrete plaques were purified, subcloned and found to contain similar inserts of 0.6 to 0.7 kilobases (kb) . FIG. 9 shows the complete nucleotide sequence (SEQ ID NO:26) of the y cDNA, the deduced amino acid sequence (SEQ ID NOΪ27) and the position in the sequence of the four original tryptic peptides. Analysis of the sequence (FIG. 10C) indicates an N-terminal hydrophobic signal peptide of 18 residues and a putative transmembrane domain separating a short extracellular portion of 5 residues from an intracytoplasmic domain. As predicted by earlier studies, the N-terminal processed ~ subunit contains two cysteines, no methionine and no tryptophan residues (G. Alcaraz et al.. Biochemistry 26:2569-2575 (1987)). Compositional analysis suggested that the y subunit might contain one histidine residue (G. Alcaraz et al.. Biochemistry 26:2569-2575 (1987)). However, biosynthetic dual labeling studies of the receptor using 3S S methionine^ and 3 H histidine, clearly indicated that no trace of histidine was incorporated into the receptor- associated subunit. since the open reading frame , histidine six residues from the C-terminal end, it is expected that the y subunit undergoes a C-terminal processing which clips off the histidine-containing segment. Furthermore, because the peptide immediately preceding this histidine was recovered (FIG. 9 and SEQ ID NO:26) , the C-terminal segment must be cleaved after Lys 63. The predicted molecular weight of the fully processed y would therefore be 7139 Da,in close agreement with values obtained for the purified reduced 7 on sodium dodecyl sulfate - urea gels (G. Alcaraz et al. Biochemistry 26:2569-2575 (1987)). Polyclonal antipeptide antibodies to a heptamer and to a nonamer peptide of the 7 subunit (FIG. 9 and SEQ ID NO:27) were prepared and tested for reactivity with IgE receptor complexes for RBL cells. Both purified antipeptide antibodies reacted in a Western blot assay with the unreduced di er and the reduced monomer of partially purified 7 subunits. In addition, both antibodies quantitatively precipitated receptor-bound I2S I-IgE, either from an extract of RBL cells or from a preparation of partially purified receptors. Taken together, these results leave no doubt that the cDNAs isolated according to the present invention code for the 7 subunit of Fc f RI. EXAMPLE 14 Expression of Receptor In order to achieve expression of the receptor on the surface of COS 7 cells, the coding region of the α, β, and 7 cDNAs were first subcloned separately into the SV 40 promoter-driven expression vector pSVL, prior to transfection into the COS-7 cells. The 810 bp EcoRI-Sty I restriction fragment of the a cDNA, the 965 bp EcoRI- EcoRV restriction fragment of the β cDNA and the 300 bp EcoRI-Dde I restriction fragment of the 7 cDNA were subcloned separately into the Sma I site of the transient expression vector pSVL (Pharmacia, Uppsala, Sweden). These restriction fragments individually conta ne the entire coding sequence of the appropriate subunit and variable portions of untranslated sequences. The only foreign sequence was the starting EcoRl recognition sequence which belonged to the initial linker. Cultured C0S7 monkey kidney cells were then transfected with 40 μl of DNA by the standard calcium phosphate precipitation technique (L. Davis et al.. in Basic Methods in Molecular Biology, ed. L. Davis, Elsevier, New York (1986)). After 48 hrs, the transfected cells (panels A and a of FIG. 11) , as well as RBL cells (panels C and D of FIG. 11) , were examined for surface expression of IgE binding by an IgE rosetting assay. The cells (5 x 10 6 cells/ml) were incubated at room temperature with (panels B and D) or without (panels A and C) μg/ml of non-specific rat IgE for 30 min and then with 5 μg/ml of anti-DNP-IgE (F.T. Liu et al.. J. Immunol. 124:2728-2736 (1980)). The cells were then rosetted with ox red blood cells that had been modified with 2,4,6-trinitrobenzene sulfonic acid according to a known method (M. Rittenberg et al.. Proc. Soc. Exp. Biol. Med. 132:575-581 (1969)). The results are shown in FIG. 11. FIG. IIA shows IgE-binding activity expressed by cells cotransfected with the α, β and 7 subunits. Virtually all RBL cells, used as a positive control, formed rosettes (FIG. 11C) . The rosettes were completely inhibited by preincubation of the cells with rat IgE (FIG. 11B and D) but not with human IgE (not shown) . This coincides with the species specificity for the rat Fc ^ RI (A. Kulczycki et al. , J. Exp. Med. 139:600-616 (1974)). In order to study the requirements for surface expression of IgE-binding activity, the cells were transfected with different combinations of the cDNAs for the three subunits, as shown in Table 2. COS-7 cells were transfected with different combinations of cDNAs for the three subunits of Fc tl (FIG. 11) . The rosetting assay was performed for each transfection shown in Table 2. The assessment of the mRNA by Northern blotting was performed one time only (on x ce s . n or was a e o e experiments marked by an asterisk in Table 2 (50 μg/ml of non-specific rat IgE was added to the cells 30 minutes prior to the addition of the specific mouse anti-DNP IgE). ♦ Experiments where inhibitor was added. Table 2 summarizes the data derived from all the transfection experiments performed as described up to here. The success rate of the transfection experiments has improved since that data was collected so that there is now routinely achieved 5±2% expression of IgE binding when α, β and y are simultaneously cotransfected. Successful transfection was achieved for all combinations, as assessed by Northern blotting, but rosette forming cells were only detected after cotransfection of the full set of the cDNAs. These results indicate that the β and 7 subunits are required for surface-expression of the IgE-binding α subunit. It is further indicated that only the fully assembled receptor reaches the plasma membrane. This phenomenon has also been observed in other systems (M. McPhaul et al.. Proc. Natl. Acad. Sci. USA 83:8863-8867 (1986); Y. Minami et al.. Proc. Natl. Acad. Sci. USA 84:2688-2692 (1987)) and may be generally applicable to polymer c membrane proteins. The easy dissociability of β and y , from α (B. Rivnay et al.. Biochemistry 21:6922-6927 (1982)) has raised persistent uncertainty about whether conceptually, 7 2 , and β should be considered as subunits of Fc,RI or as "receptor associated" proteins. (An example of the latter is the CD3 complex which associates with the antigen receptor on thymus-derived lymphocytes (H. Clevers et al. , Ann. Rev. Immunol. 6:629-662 (1988)). The subunit model for Fc < RI has been favored, for example, on the basis of the coordinate biosynthesis and catabolism of α, β and y, (R. Quarto et al.. Molec. Immunol. 22: 1045-1052 (1985)). The new data on transfected cells obtained by the present invention provides the strongest evidence yet obtained that αfi72 is the minimal structure for Fc < RI. The present model for the tetrameric Fc e RI receptor is illustrated in FIG. 12 and SEQ ID NOs. 28-30. In this model each of the 589 amino acid residues of which the expressed receptor is composed is shown as a circle. In the diagram, the exterior of the cell would be at the top, the plasma membrane in which the receptor is embedded would be in the middle, and the interior of the cell towards the bottom. Each of the polypeptide chains (the a, SEQ ID N0:28, on the left, the β, SEQ ID NO:29, chain in the middle and the two 7, SEQ ID NO:30, chains on the right) contains one or more transmembrane segments. The α chain (SEQ ID NO:28) is believed to contain two intrachain disulfide loops, and the sequences of these loops show considerable homology with immunoglobulins (J.P. Kinet et al.. Biochemistry 26:4605 (1987); A. Shimizu et al, Proc. Natl. Acad. Sci. USA 85:1907 (1988) ; J. Kochan et al.. Nucleic Acids Res. 16:3584 (1988)). Thus, the α subunit is another member of the immunoglobulin superfa ily (A. Williams et al.. Ann. Rev. Immunol. 6:381 (1988)). The extracellular and transmembrane segments of the α chain show considerable omo ogy w e mmunog o u n n ng c a n o receptors that bind IgG (J. Ravetch et al. , Science 234:178 (1986)), but the intracellular cytoplasmic tail is quite different. The carbohydrate residues that are covalently attached to the extracellular portion of the a chain are not indicated in FIG. 12. There are seven potential sites for N-linked carbohydrates (J.P. Kinet et al.. Biochemistry 26:4605 (1987); A. Shimizu et al.. Proc. Natl. Acad. Sci. USA 85:1907 (1988)), but which of these that are actually used by the cell remains to be determined. Studies show that the carbohydrate is not essential for the binding of IgE by this chain (B. Hempstead et al, J. Biol. Chem. 256:10717 (1981)). The β chain (SEQ ID NO:29) contains four transmembrane segments (J. P. Kinet et al.. Proc. Natl. Acad. Sci. USA 85:6483 (1988)) and previous studies with monoclonal antibodies (J.P. Kinet et al.. Proc. Natl. Acad. Sci. USA 85:6483 (1988); J. Rivera et al. f Mol. Immunol. 25:647 (1988)) show that the amino- and carboxyltermini which are respectively 59 and 43 residues long, protrude from the cytoplasmic face of the plasma membrane. Similarly, the y chains (SEQ ID NO:30) have an extensive intracellular extension but only very limited exposure to the exterior. According to the general model, the putative transmembrane domains of the individual subunits are predicted from their respective hydropathicity plots (see FIG. 10, wherein a net free energy of > 20 kcal/mol for transfer to water suggests a transmembrane segment or a leader peptide (D. Engelman et al.. Ann. Rev. Biophys. Biophys. Chem. 15:321-353 (1986)). These plots suggest one, four and one hydrophobic domains for the α, β and each 7, respectively (i.e., seven transmembrane domains for the entire receptor) . Members of a family of receptors interacting with G proteins also contain seven transmembrane domains (I. Herskowitz et al.. Cell 50:995- 996 (1987)). This family includes β and α adrenergic, muscarinic receptors and rhodopsin. Although no sequence homology between Fc r RI and these receptors is found, it is significant that an interactioή ** beT_T*eert"Fc^RI and "G proteins has been postulated to explain at least some of the biochemical pathways activated by this receptor (S. Cockcroft et al. , Nature 314:534-536 (1985)). The topology of the α and β subunits has been discussed in J.P. Kinet et al.. Biochemistry 26:4605-4610 (1987) and A. Shimizu et al. , Proc. Natl. Acad. Sci. USA 85:1907- 1911 (1988) , in particular, the cytoplasmic localization of the C- and N- terminal portions of the β subunit. Two pieces of evidence support the topology of the 7-dimer as shown in FIG. 12: The 7 can be oxidatively iodinated on inverted vesicles but not on intact cells (D. Holowka et al.;, J. Biol. Chem. 259:3720-3728 (1984)) and, in vivo, 7 becomes phosphorylated on threonine residues (R. Quarto et al., Mol. Immunol. 23:1215-1223 (1986)). None of the relevant residues are present in the small presumptive extracytoplasmic segment of 7 but all are present on the presumptive cytoplasmic tail, i.e. , two tyrosine and four threonine residues. As a further means to examine the topology of the receptor, the putative extracellular and intracellular segments of the three subunits were analyzed for their relative content of basic residues, as suggested by G. von Heijne Biochi . Biophys. Acta 947:307-333 (1988). He found the ratio of basic/total residues varies as a function of the length of the segment studied, but in general was substantially higher in the non-translocated (intracellular) segments than in the translocated (extracellular) segments of membrane proteins. Table 3 below shows a good correspondence between the ratios calculated for the present model and the ratios expected on the basis of "known" membrane proteins (G. von Heijne, Biochim. Biophys. Acta 947:307-333 (1988)), thereby providing independent support for the topological model presented here. TABLE 3 Ratio Lye + Ar /to l in Translocated and Untranalocaled Segment* of Receptor Subuniu The expected value* calculated from the data in FIG. 8 of C. von Heijne, Biochim. Bioohv*. Act* 947. 307-333 (1988). in which the ratio found for the exua-membrane aegmenti from 'known' protein* haa been plotted aa a function of the segmenu' length. The model clarifies several important features with respect to the organization of the subunits. The β and dimer of y interact with each other; in detergent solutions they dissociate from 5the a as a unit before dissociating from each other (J. Rivera et al.. Mol. Immunol. 25:6-.7-661 (1988)), and occasionally, β and the 7 dimer are observed to be disulfide-linked to each other (J.P. Kinet, Biochemistry 22:5729-5732 (1983)). The likeliest candidates for this bond are 7-cys7 and β-cys80 which are predicted to be topologically close. This would then require that at least the 7-cys26 residues are disulfide-linked in the y dimer. Preliminary data on the receptor biosynthesis suggest that and β interact with each other. The functional properties of Fc f RI are broadly similar to those of several Fc 0 R. FC γ R appears to bind to homologous segments of the immunoglobulin*s Fc region (B. Helm et al. , Nature 331:180-183 (1988); A. Duncan et al.. Nature 332:563-564 (1988)), and the binding site on the receptor is found on a homologous polypeptide having immunoglobulin-like domains (J.P. Kinet et al.. Biochemistry 26:4605-4610 (1987) ; J. Ravetch et al. , SUBSTITUTE SHEET Sc ence 234:718-725 (1986)). Bot ypes o receptors need to be aggregated to initiate cell activation and, where studied, the latter appears to involve generation of broadly similar second messengers (H. Metzger et al. , Ann. Rev. Immunol. 4:419-470 (1986); N. Hogg, Immunol. Today 9:185-187 (1988)). It is surprising, therefore, that whereas Fc < RI consists of four polypeptide chains, seven transmembrane segments and five cytoplasmic segments, Fc c RI appear to perform similar functions with a much simpler structure, i.e., an α-like subunit alone. The extreme case is that of Fc^RIII which appears to lack even transmembrane and intracellular segments (P. Selvaray et al. , Nature 333:565-567 (1988); D. Simmons et al.. Nature 333:568-570 (1988); T. Huizinga et al. , Nature 333:667-669 (198S) ) . It has been suggested that additional components of FC7 receptors may have thus far been missed. Possibly such components are even more easily lost upon solubilization of the receptors than are the β and 7 subunits of FRl (J.P. Kinet et al. , Biochemistry 24:4117-4124 (1985)). A reasonable interpretation is that such hypothetical components would be homologous to β or 7 or both. The availability of genetic probes for the latter components will now permit an in-depth exploration of this possibility. The success in expression of IgE binding achieved according to the present invention has important therapeutic implications. Degranulation of mast cells and basophils triggered by Fc t RI accounts for many of the symptoms of allergy. Given the high incidence of this disorder, the discovery of a specific inhibitor of IgE binding is expected to yield enormous therapeutic benefits. The development of such an inhibitor has been hampered by the lack of a practical in vitro assay for the binding of human IgE to the human receptors. For example, a recent assessment of IgE-derived peptides of their inhibitory capacity had to be determined by skintesting (B. Helm et al.. Nature 331:180-183 (1988)), a cumbersome and potentially dangerous procedure. SUBSTITUTESHEET ISA/EP That the present nvent on ach eves e express on of the transfected rodent receptor indicates that human Fc t RI can be similarly expressed. Alternatively, since at present only the cDNA coding for the human α subunit has been isolated (A. Shimizu et al.. Proc. Natl. Acad. Sci. USA 85:1907-1911 (1988); J. Kochan et al.. Nucl. Acids Res. 16:3584 (1988)) , it is expected that it can be expressed in cotransfections with the cDNAs coding for the rodent β and y chains. A comparison between the human and rat o subunits is set forth in Table 4 below. TABLE 4 Comparative Properties of Human and Rat Alpha Chains It may be seen from the above Table that there is an overall homology between the human and rat alpha chains of about 47%, but an almost 70% homology in the presumed transmembrane domains. Indeed, when the transmembrane domains are examined closely, there is a stretch of 10 consecutive residues that are completely identical. This stretch of consecutive residues is underlined in Table 4. Because the transmembrane segment is the region of the α chain that is most likely to interact with the βl and chains, it was expected that the human α chain would be expressible, if transfected, along with the rat β and chains. This has proved to be the case as the present inventors have been able to express human IgE binding by COS cells transfected simultaneously with the human and the rat β and γ subunits. It will be SUBSTITUTESHEET ISA/EP , , cell lines and for such lines, one will want to utilize combinations of the IgE receptor subunits disclosed herein. EXAMPLE 15 The Beta Subunit of FC.R Is Necessary for Expression in Mast Cells FIGS. 20 and 21 present the results obtained from FACS analysis (IgE binding) of cells transfected with FIG. 20: represents COS-7 transfected cells. FIG. 21: represents KU812 cells (a basophil line) . The clone of Ku812 cells used does express the mRNA for the three svibunits alpha, beta and gamma but the receptor is not naturally expressed on the surface. In FIG. 20, the transfection of human alpha and gamma in COS-7 cells is confirmed to be sufficient for expression of the alpha-gamma complex on the surface of the transfectants. These results also show that human beta and not rat beta associates efficiently with human alpha and that therefore, rat beta cannot replace human beta. FIG. 21 illustrates that transfection of alpha-gamma in KU812 results in very little expression of receptors. The level of expression is similar to the level obtained after transfection of beta and gamma. Therefore this level may be attributable to the endogenous alpha (for beta and gamma transfection) or to the endogenous beta (for alpha and gamma transfection) . By contrast the level of expression after co-transfection of the three cDNAs is very substantial. From these results, it may be concluded that: 1. in mast cells and basophils, regulation of the level of expression of the receptor may be different than in fibroblasts. 2. in human mast cells and basophils, receptor expression requires the presence of alpha, beta and SUBSTITUTESHEET ISA/EP , and gamma are sufficient. EXAMPLE 16 Isolation. Mapping and Sequencing of the Human FceRI β Gene Initial atempts to isolate human β cDNA clones were by screening a human mast cell cDNA library with full- length rat and mouse cDNA probes. These probes were radiolabeled and used to screen 7xl0 5 colonies. Four clones were isolated, all of which contained a 153 bp insert with 73% homology to rat β cDNA. The sequence of this insert corresponded to a portion of β which includes the intracellular loop and the third transmembrane domain. These four identical clones are the likely result of library amplification of a single clone generated by recombinations. Two additional libraries were screened: another mast cell cDNA library and a cDNA library derived from basophil-enriched leukocytes. The latter library was also used to isolate human y cDNA clones. A total of 107 independent cDNA clones were screened with a panel of murine probes and oligonucleotides and with the 153 bp human β probe. However no additional clones were isolated. 6x10 s independent genomic clones from a human genomic leukocyte library with the radiolabeled 153 bp human probe were subsequently screened, and 10 clones with an average size insert of 25 kb were isolated. These clones all hybridized with two 20 mer-oligonucleotide probes corresponding to the beginning and the end of the rat β coding y sequence. Four different restriction patterns could be generated from the 10 clones. However, southern blots with various oligonucleotide probes scanning different regions of the rat β coding sequence indicated that the four restricted patterns were not the product of different genes. Rather the clones showed differences in the lengths of the sequences flanking the β gene. One clone containing a 25 kb insert was chosen for further characterization mapping and sequencing. A SUBSTITUTE SHEET ISAEP res r c on map s own n g. was cons ruc eα y complete and incomplete digestion with the restriction endonucleases Hind III, Pst I, BamH I, Xba I, Sma I and Kpn I. A 3.2 kb Hind III fragment was found to hybridize with oligonucleotide probes corresponding to the start codon, and transmembrane region I and II of rat β . A 2.8 kb Sma I fragment hybridized with rat β probes of transmembrane domain III and IV and a 4.5 kb Sma I fragment with probes of the stop codon region. The 3 fragments were subcloned into pGEM 3zf (+) or (-) and sequenced in full (TIG. 14 and SEQ ID NO:31) . The fragment corresponding to the 0.9kb gap between the Hind III and 2.8 kb Sma I fragments was produced by PCR and sequenced. Analysis using PCR confirmed that the two Sma I fragments were adjacent to each other. By comparing the sequences of the human β gene and the rat β cDNA (FIG. 15) seven homologous regions which were likely localized to correspond to seven different exons. EXAMPLE 17 Synthesis of Human 6 cDNA Coding Sequence In order to confirm the sequence of the exons and to define the intro-exon borders, human β cDNA was synthesized by reverse transcription of RNA purified from basophil-enriched leukocytes followedby an amplification of the reverse transcripts using the polymerase chain reaction (PCR) (described in Materials and Methods herein) . This applied product extended from 2 nucleotides preceding the start codon to 32 nucleotides following the stop codon. The cDNA sequence was found to be identical to the corresponding sequence of the human β gene. This confirmed that the coding sequence of human β is contained in seven exons. Furthermore, the comparison of cDNA and gene sequences and the detection of consensus sequences for intron-exon borders in the human β gene allow for a precise determination of these SUBSTITUTESHEET borders. The 5* borders of the six intervening introns invariably start with GT and the 3 ' borders end with AG.• EXAMPLE 18 Analysis of Human 6 Transcripts To evaluate the length of 5' and 3• untranslated sequences, the size of human β transcripts was analyzed. RNA from basophil-enriched leukocytes obtained from different individuals were hybridized by northern blotting with the radiolabeled 153 bp human β probe (FIG. 16A) Two transcripts around 3.9 kb were found in human basophils but not in COS-7 cells. The human transcripts are substantially longer than their rodent counterparts (2.7 and 1.75 kb) (Ra. 1989, Kinet, 1988) as detected in RBL cells by crosshybridization. This longer size may explain initial failures to isolate human β cDNAs from the three oligo-dT primed libraries. Similar results were obtained with a full-length cDNA probe of human β . Hybridization of the same RNAs with a hvunan α cDNA probe revealed transcripts for o of the expected size (1.1 kb) (FIG. 16B) . RNA from different cell lines were also hybridized with a full length human β cDNA probe (FIG. 16C) . The message for human β is only detected in the basophil line KU812 but not in U937, Daudi and Hela cells. An additional band is seen in KU812 which could correspond to unspliced transcripts. With an open reading frame of 732 bp and assuming 200 bp for the poly A tail, human β transcripts should contain about 3 kb of untranslated sequences. FIG. 15 shows that most of the untranslated sequences are in the seventh exon. The possibility that additional exons of 3' or 5' untranslated sequences had not yet been identified was also explored. SUBSTITUTESHEET A. Characterization of the (A) 5' End and of the Transcription Initiation Site The transcription start site was determined by sequencing directly a PCR amplified product of the reverse transcribed RNA as described in "Experimental Procedures". RNA from basophil-enriched leukocytes was reverse transcribed from a primer of the human β coding sequence. Poly-A tails were added to the reverse transcripts by treatment with terminal transferase and the resulting cDNAs were amplified by PCR. Single stranded DNAs (positive strands poly dT tailed) were then produced by asymmetric PCR and directly sequenced. The cDNA β sequence of the negative strand corresponding to the 5' end of the RNA is shown in FIG. 5A and is compared to the relevant sequence of the β gene. The perfect match between the two sequences ends after GGGTT. Then the cDNA sequence reproducibly shows a C, which is not present in the gene, followed by the expected poly-A tail. This additional C may correspond to the G of the cap structure and indicate the location of the start site. Experiments of 5" extension (FIG.17B) confirmed that there is a major start site in this area (about 11 nucleotides 3• of the position described above) . It is difficult, though, to exclude the possibility that the faint bands seen below and above the major start sites correspond to minor start sits. However the presence of a TATAAA box found in the 5* sequence supports the existence of a unique start site. In addition the location of the TATAAA box (usually 25 nucleotides 5' of the start site) is more consistent with the precise localization of the start site as shown. Indeed the TATAAA box is located between nucleotides 29 and 24 upstream of this start site as shown in FIG. 17A. Taken together the data indicate that the human β mRNA start with the sequence AACCC (see FIG. 14, SEQ ID NO:31, and FIG. 17A) and has 102 bp of 5' untranslated sequence. SUBSTITUTE SHEET ISAEP . A comparison between the rat β cDNA and human β gene sequences FIG. 15) shows that the seventh exon of the β gene extends at least from nucleotides 6773 to at least nucleotide 8910. But an additional 3 1 untranslated sequence (about 800 bp) had to be found to fully account for the 3.9 kb transcripts. To analyze whether the missing sequence was part of the seventh exon or of other undetected exons, three probes from the β gene were prepared to test their reactivity with β transcripts. These transcripts hybridized in northern blots with both the Nsil-BamHl fragment (nucleotides 8460-9250) and the BamHI-SphI fragment (nucleotides 9250-9714) but not with the fragment 3 » of the SphI site. Interestingly two polyadenylation signals AATAAA are found at nucleotides 9663 and 9758 (FIG. 14 and SEQ ID NO:31). Therefore this region is likely to correspond to the end of exon 7. It is likely that both polyadenylation signals could be used to create the apparent doublet of transcripts around 3.9 kb (see FIG. 16) . EXAMPLE 20 Organization of the Human 6 Gene Taken together the data presented herein indicate that the human β gene contains seven exons and six introns and spans about 10 kb. Exon 1 codes for 102 bp of 5' untranslated sequence and the first 18 amino acid residues of the N-terminal cytoplasmic tail. Exon 2 encodes the remaining of the cytoplasmic tail and the first three residue of TM1. Exon 3 codes for the remaining of TM1, the first extracellular loop and the first half of TM2. Exon 4 encodes the second half of TM2 and a portion of the cytoplasmic loop. Exon 5 codes for the last three residue of the cytoplasmic loop, TM3 and most of the second extracellular loop. Exon 6 codes for the last two residues of the extracellular loop, TM4 and the first quarter of the C-terminal cytoplasmic tail. SUBSTITUTESHEET ISA/EP , cytoplasmic tail and the long untranslated 3' sequence. EXAMPLE 21 The Human 6 Protein The human β protein comprises 244 amino-acid (aa) residues and has a molecular mass of 26,532 daltons (FIG. 18) . Similar to rat (243 aa) and mouse β (236 aa) , human β contains four hydrophobic segment suggestive of transmembrane domains (TM) but no leader peptide. FIG. 19 shows an alignment of the human sequence (SEQ ID NO:32) with the rat (SEQ ID NO:33) and mouse (SEQ ID NO:34) sequence. The consensus sequence for β (not shown) from the three species (rat, mouse and human) shows that 91.4% of the amino-acid residues are homologous while 68.7% are identical. SUBSTITUTESHEET ISA/EP Transfection in COS-7 Cells: Expression of Human and Hybrid Fc.RI Receptors Table 5 Functional expression of FcεRI after transfection of various subunit combinations Transfected cDNAs % Fluorescent cells (FACS) n Mean + SD Human a - 10.2 Human α Human β 10.2 Human a - Human y 7 10.4 + 8.7 Human Human β Human y 78.3 + 5.0 Human α Rat β Human 7 45.4 + 3.4 Rat β Rat β Rat 7 8 18.0 + 17.8 Rat Hvunan β Rat 7 102.4 ± 2.0 Rat α Hvunan β Hvunan 7 51.8 + 1.3 Mouse α Mouse β Mouse 7 Mouse a Human β Mouse 7 Mouse a Human β Human 7 Human a - Rat y u^ Human a Rat β Rat 7 . U tnmc Hvunan α Human β Rat f U tiunc Rat Rat β Rat y^ 0.8 Rat α Human β Rat y^ ^ . It was found that co-transfection of α, β , and 7 cDNAs is necessary to promote expression of rat or mouse Fc t RI on the surface of transfected COS-7 cells. By contrast, co-transfection of hvunan α and β cDNAs results in the surface expression of 07 complexes without apparent need for 7. With the availability of human 7 cDNAs, the question was explored whether hvunan β would influence in any way the efficiency of surface expression o e uman recep or comp ex. a e s - transfection of human α and y cDNAs into COS-7 cells results in 10.4% ± 8.7 of the cells being fluorescent when analyzed by FACS after binding of fluoresceinated IgE. This level of expression is not significantly modified when human β cDNA is co-transfected with human α and y cDNAs (8.3% ± 5.0) . Thus, human β does not seem to influence the level of surface expression of human FceRI in transfected COS-7 cells. Substituting rat β or human β reduces the level of expression (5.4% + 3.4). The effect of substituting human β for rat β was analyzed. Co-transfection of rat α, β , y cDNAs result in much higher level of expression (18.0% + 17.8) than co- transfection of rat α, y with human y (2.5% + 2.0) (Student's t statistic = 2.75; p<0.014). Similarly co- transfection of mouse α, β, y cDNAs is more efficient (8.2% + 5.6) than co-transfection of mouse α, y with human β (1.6% + 1.2) (Student's t statistic:2.91; p<:0.019) . Because replacing rat y or mouse y with human 7 does not restore expression (compare 2.4% with 1.8%, and 1.6% with 1.5%), it is likely that the problem of expression resides in the human S-rat a or hvunan /3-mouse a interaction. It is known that truncation of the cytoplasmic tail of rat 7 prevents the surface expression of human α in transfectants (Varni-Blank, 1990) . The question was whether human β could complement the surface expression of human α in these conditions. It was confirmed that co-transfection of human a with truncated rat 7 permit only very poor surface expression of 07 complexes (1.4% + 1.0). When human β is co-transfected with the latter combination there is an increase of expression (7.4% + 7.3, n=7) . However this increase does not become significant (p<0.035) when one aberrant point is not included in the seven experiments. The same increase is not observed when rat β is substituted for human β (3.2% + 2.8) suggesting again that there may be specific points of interaction between human a and β . In other experiments using the truncated rat 7, it was found that n canno e su s u e or r interaction with rat a (compare 9.3% ± 0.6 with 0.4% + 0.4; (t = 13.0; p<0.006). Taken together these data indicate that there is a tendency for hvunan β to interact more efficiently with human α than does rat β , but the species specificity is weak. By contrast, there is a strong species specificity in the interaction between rat β and rat α or between mouse β and mouse α. Human 0:7 complexes may be expressed on the surface of transfected cells. Moreover co-transfection of human α and 7 with rat β results only 20% of the receptors being α/37 complexes, the remaining 80% being 0:7 complexes. Therefore, it is theoretically possible that 07 complexes occur naturally. However in view of the species specificity of interaction between human β and α (see above) , previous results obtained from the co- transfection of human α and 7 with rat β suggest the in vivo situation could be different. These genetic results, of course, provides much more than an assay, as important as the latter may be. Through directed mutation it will, in addition, allow the development of further information regarding the critical binding regions. It is expected that, using this information, rational drug design will become possible. It is further expected that it will be possible to block the function of the receptor itself, i.e., it will be possible to interfere with the early biochemical signals that result from activation of the receptor. EXAMPLE 23 Detection of a Candidate Inhibitor Substance In still further embodiments, the present invention concerns a method for identifying new Fc t RI inhibitory compounds, which may be termed as "candidate substances." It is contemplated that this screening technique will prove useful in general identification of any compounds that will serv e the purpose of inhibiting the formation ^ s e . (Mouse Interleukin-2 ELISA kit, Alberts et al.. pp. 179- 180, Adamczewski et al. (in press), Barones et al. , 1991) . Thus, in these embodiments, the present invention is directed to a method for determining the ability of a candidate substance to inhibit the formation of the human Fcβl complex, the method including generally the steps of: (a) obtaining a composition comprising the human alpha, beta and gamma subunits of Fc c RI that are capable of complexing to form a functional and/or expressed receptor; (b) admixing a candidate inhibitor substance with the composition; and (c) determining the functional or expressed ability of the admixture. An important aspect of the candidate substance screening assay hereof is the ability to prepare a composition of alpha, beta and gamma svibunits in a relative purified form, for example, in a manner discussed herein. An aspect of the candidate substance screening assay in that without at least a relatively purified preparation, one will not be able to assay specifically for Fc < RI inhibition, as opposed to the effects of the inhibition upon other substances in the extract which then might affect the receptor. In any event, the successful cloning and isolation of the beta subunit now allows for the first time the ability to identify new compounds which can be used for inhibiting the Fc^I in specific ways, thereby inhibiting the effects of the Fc,RI when bound to IgE. The candidate screening assay is quite simple to set up and perform, and is related in many ways to the assays discussed above for determining Fc ^ RI activity. After obtaining a relatively purified preparation of the alpha, beta and gamma subunits, one will desire to simply admix a candidate substance with the preparation, preferably under conditions which would allow the receptor to form u or nc us on o an n ory su s ance. , example, one will typically desire to use cell activation assays as indirect measures of the presence of a functional receptor, or receptor expression, or both. Accordingly, one will desire to measure or otherwise determine the activity of the relatively purified receptor in the absence of the assayed candidate substance in order to assess the relative inhibitory capability of the candidate substance. In still further embodiments, the present invention is concerned with a method of inhibiting receptor formation and/or function which include subjecting the subunits to an effective concentration of a candidate substance identified in accordance with the candidate screening assay embodiments. This is, of course, an important aspect of the invention in that it is believed that by inhibiting the receptor one will be enabled to treat or prevent various aspects of allergic reactions. It is believed that the use of such inhibitors to block the release of histamine by binding of IgE to Fc < RI and serve to treat or palliate the symptoms of an allergic response. Inhibitors may be useful by themselves or in conjunction with other therapies. EXAMPLE 24 Identification and Use of Fc τ RI Inhibitors If the action of receptor of IgE is inhibited, the allergic reaction will not proceed. This inhibition may be either at the level of transcription, translation, or protein action. Interference with transcription would necessitate interference with mRNA formation on the DNA template. Preferably, interference with the translation would necessitate interfering with the synthesis of proteins on the mRNA template. Alternatively, the action of the receptor may itself be disrupted either by destroying the structure of the receptor, prohibiting its formation, or binding the receptor or components thereof irreversibly to inhibitors. pec ca y es gne pep es w c oc e unc on of the receptor are extremely valuable in preventing and treating allergic diseases. Embodiments of these blockers (antagonists) include any substrate analogues or inhibitor, e.q. , oligopeptides or their derivatives which contain the amino acid sequence of the IgE binding site. Methods for identifying suitable inhibitors form candidate substances are disclosed in Example 23. EXAMPLE 25 Preparation of the Human R Polypeptide by Recombinant Techniques It is an additional object of the present invention to provide a ready means for producing the human beta subunit for use in detecting inhibitors, to develop treatmentmodalities, to develop antibodies for detection of the subunit, and to develop inactive mutants of the human beta subunits, which may also be use to inhibit formation of the Fc < RI. Such mutants may be introduced into transgenic animals, for example, to produce animals useful for β assays. An exemplary embodiment for preparing the beta subunit protein is to prepare a nucleic acid segment which includes a nucleic acid sequence capable of encoding the desired protein or polypeptide. This segment may be that which encodes the entire subunit or only some portion of it, for example, the alpha or gamma binding domain of the subunit. The segment may be as small as that capable of triggering a positive signal with an antibody, thereby, identifying the presence of a beta subunit. Segments functionally equivalent to those shown in Fig. 14, may also be selected depending on the desired polypeptide to be produced. Functional equivalence may be determined by testing whether the segment can cause cell activation using techniques disclosed herein to detect inhibitors from among candidate substances. e nuc e c ac segmen se ec e s rans erre n o an environment appropriate for expression of the segment as a polypeptide. This environment may be a vessel containing a mixture capable of inducing expression. Alternatively, the segment may be transferred to a host cell by transformation, transfection via a recombinant expression vector, electroporation, or a "gene gun." The host cell may be selected from CHO cells, T cells, KU812 cells, P815 cells, or the like. The recombinant expression vector will generally include a promoter. Embodiments of promoters are the α4 promoter, or any other suitable prokaryotic or eukaryotic promotors. EXAMPLE 26 Antibodies Against the Proteins of the Present Invention In other embodiments, the invention concerns the preparation of antibodies to the beta subunit of Fc < RI and species derived therefrom, either recombinant or nonrecombinantly prepared. Compositions which include monoclonal antibodies of the present invention may be prepared by first fusing spleen cells of a rodent with myeloma cells from the same rodent species, wherein the rodent providing the spleen cells have been immunized with the β subunit peptide, precursor, or related peptides. The rodent species utilized will generally be a mouse. Of course, where a beta subunits is prepared which incorporates structural variations over the ones disclosed herein, it will likely be able to successfully employ a hybridoma system according to the species of interest. In addition, the present invention provides a method for isolating beta subunits from other species which may be found antigenically cross-reactive with that of the human or rodent subunit. This method includes preparing an immunoabsorbent material having attached thereto an antibody to the subunit. Numerous immunoabsorbent o o include, for example, Affi-Gel, Cn-Sepharose, protein A=Sepharose, and numerous other well know immunoadsorbent techniques. All such techniques of the immuno cross- reactive species (for a more complete listing, see Monoclonal Hybridoma Antibodies: Techniques and Applications. John G. Hurrell, ed. CRC Press, 1982, incorporated herein by reference) . Materials and Methods Screening of cDNA and σenomic libraries The human basophil cDNA library and the human leukocytes genomic library have been described before and are available (Kuster, 1990) . The human lung cDNA library (Miller, 1989) and a human skin cDNA library were provided by L.B. Schwartz (Medical College of Virginia, Richmond) . The following probes were prepared for screening the various libraries: The EcoRI*-EcoRV fragment of rat β (Kinet, 1988) and the EcoRl fragment of mouse β (Ra, 1989) , both of which contain the entire coding sequence of β and part of the 3' untranslated region. Fragments of the coding region of rat β cDNA (bp 1-304) and mouse β cDNA (bp 433-708) were made by polymerase chain reaction (PCR) . Multiple oligonucleotides corresponding to various regions of rat, mouse and human β were synthesized on a model 380A automated DNA synthesizer (Applied Biosystems, Foster City, CA) . All double stranded DNA probes were radiolabeled by random primer labeling and the oligonucleotides by end labeling as described elsewhere (Davis, 1986) . Hybridization and washing conditions and procedures for plaque purification subcloning, sequencing and DNA. analyεis were as described previously (Kuster, 1990) . ■ Digestion of genomic DNA from five different individuals with BamH Bgl II, Eco RI, Hind III, Msp I and Pvu II and hybridization of these digests with a hvunan cDNA probe (from start to stop codon) supports the existence of a unique gene (FIG. 18) . In addition the lengths of the restriction fragments detected on the southern blot are entirely consistent with the lengths predicted from the sequence of the gene. Three BamHI sites (nucleotide 156, 6908, 9250) are presenting the gene. As expected only one fragment (156-9250) is seen here because the other fragments should not hybridize with the cDNA probe. The two predicted Bgl II fragments (+334 to +1766 and +1766 to +7419) and the two predicted Hind III fragments (-454 to +2724 and +2724 to 100042) are readily detected. The results obtained after EcoRl and PvuII digestions are consistent the fact that none of these sites are found in the sequence of the gene. Finally the pattern observed after Msp I digestion is also consistent with predicted fragments of 2067 bp, 3870 bp and a larger 5' fragment extending from nucleotide 3622 to an undetermined Mspl site upstream of the gene. cDNA synthesis by using the Polymerase Chain Reaction (PCR) Basophils from 240ml of blood were purified by double Percoll gradients as previously described (Warner, 1987) and basophil RNA extracted by the guanidium isothiocyanate method (Davis, 1986) . Two μg of total RNA were reverse transcribed with Superscript reverse transcriptase using a random 9-mer primer as recommended by the manufacturer (Bethesda Research Laboratories, Gaithersburg MD) . One twentieth of the reaction product was amplified using the following primers: a 23-mer complementary to nucleotide -2 to +21 of the human β coding sequence and as backward primer a degenerated 21- mer of the mouse and rat β sequences starting 32 nucleotides after the stop codon. Temperature cycles were as follows: 1 cycle of 2 min. 95° / 2 min. 94° / 5 . . , . . 37° / 4 min. 72°, and 36 cycles of 40 sec. 94° / 1 min. 50° / 4 min. 72° followed by a single 15 minute extension. One μl of this reaction was reamplified omitting cycles 2 to 5 and the amplification product subcloned into pCRlOOO using the TA cloning kit (Invitrogen, San Diego, CA) . Direct sequencing of σene fragments obtained by PCR Purified insert-containing phage DNA from the leukocyte genomic library was linearized with NotI and lOOng amplified with primers flanking the region to be sequenced. DNA amplification was achieved using 40 of the following cycles: denaturation for 1 min. at 94°C, annealing or 2 min. at 45-50°C and extension for 3-6 min. at 72°C. Subsequently 1 μl of the amplified material was reamplified in three separate reactions (50 μl) Under identical conditions omitting one of the 2 primers in order to generate single stranded DNA. The three reactions were pooled, applied to an Ultrafree MC 30.000 spin column (Millipore, Bedford MA) , and washed four times before being evaporated by vacuum. The single stranded DNA was sequenced by using the omitted primer or an internal primer. The comparison of sequences obtained by this method or by sequencing non amplified fragments being subcloned in pGEM vectors revealed no differences. Sequencing the transcription start site PCR was used to define the transcription start site. Procedures published elsewhere (Frohman, 1987) were modified as follows: 5 μg RNA were reverse transcribed as detailed above by using a primer corresponding to nucleotide +451 to 429 of the coding region. The resulting product was washed on a Centricon 100 column (Amicon, Beverly MA) and a poly-A tails were at both ends addedusing terminal transferase (Bethesda Research Laboratories, Gaithersburg MD) as recommended by the manufacturer. One sixth of this reaction was amplified with the following 2 primers: a 33-mer consisting of the e e a primer derived from nucleotide 331 to 308 of the human β coding region sequence. Subsequently an internal amplification was performed exchanging the 3 * primer for one equivalent to nucleotide +189 to 169. Finally, single stranded DNA was produced for sequencing by using an oligonucleotide corresponding to nucleotide 54 to 33 as the only primer. For all PCR's the annealing temperature was 45°C, the extension time 3 min. Analysis of the transcription start site by 5 ' extension An end labeled oligonucleotide corresponding to the negative strand at nucleotide 54 to 33 after the start codon was hybridized overnight at 42°C to either 10 μg total RNA from enriched basophils or 10 μg tRNA, followed by extension with Superscript reverse transcriptase (Bethesda Research Laboratories, Gaithersburg MD) at 45°C for 90 min. The primer-extended products were separated on a 5% polyacrylamide urea gel in parallel with the sequencing reactions of the genomic DNA. Cell Line KD812 A new myeloid cell line (KU812) was established from a patient with blastic crisis of chronic myelogenous leukemia. His blasts were morphologically characteristic of immature basophils and basophil colonies were grown in agar culture of the blood mononuclear cells. Suspension culture of his blood cells was continue for more than 2.5 years. The KU812 cells morphologically showed a fine reticular nuclei with nucleoli, and some of them contained metachromatic granules with toluidine blue (TB) staining. These granules were positive for astra blue (AB) staining. Immunological marker studies revealed that there were no lymphoid characters except Fc receptors. The KU812 cells grew colonies in in vitro agar cultures, which were proved to be composed of basophils by TB staining and AB staining. Cytogenetic analysis showed marked aneuploidy and was positive for the Philadelphia chromosome (Ph 1 ) . The cell lysate was prove o con a n s am ne. ese a a sug KU812 is a cell line from leuke ic basophil precursors. This is the first human basophil cell line. KU812 is useful in clarifying the mechanism of basophilic differentiation of the stem cells. (Kishi, Leuk. Res, 1985, a: 381-390) . Other methods Northern and Genomic Southern blots were performed as described elsewhere (Davis, 1986) . The various cDNAs were subcloned into the eukaryotic expression vector pCDL-SR(α) for the transfection studies (Takebe, 1988) . COS-7 cells were transfected by the standard DEAE-Dextran method (Maniatis, 1982) , except that a 3 minute incubation of the transfected cells in 10% DMSO in media as added after the chloroquine treatment. While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention. The references listed below are incorporated herein by reference to the extent that they supplement, explain, provide a background for, or teach methodology, techniques and/or compositions employed herein. 1. Adamczewski et al.. Evidence for two distinct kinase/phosphatase pathways in the activation of receptors coupled to non-receptor-kinases. in press) 2. Alberts et al.. Molecular Biology of the Cell. 1983, pp. 179-180. 3. Baranes and Razin, Blood. 78: 2354-2364 (1991), Collaborative Biomedical Products, Becton-Dickinson, Catalog No. 30032, lot 904092, Mouse Interleukin-2 ELISA kit. 4. Blank, U. , Ra c. , Miller, L. , White, K. , Metzger, H., and Kinet, J.P. (1989) Nature 337, 187-189. 5. Davis, L.G., Dibner, M.D. , and Battey, J.F. (1986) Basic Methods in Molecular Biology, Elsevier Science Publishing Co., New York 6. Frohman, M.A. , Dush, M.K. , and Martin, G.R. (1988) Proc. Natl. Acad. Sci. 85, 8999-9002 7. Huppi, K.. Siwarski, D., Mock, B.A. , and Kinet, J.P. (1989) J. Immunol. 143, 3787-3791. 8. Huppi, J. , Mock, B.A. , Hilgers, J. Kochan, J. , and Kinet, J.P. (1988) J. Immunol. 141, 2807-2810. 9. Kinet, J.P., Blank, U. , Ra, c. , White, K. , Metzger, H. , and Kochan, J. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 6483-6487. 10. Kinet, J.P. (1990) Curr. Opinion Immunology 2, 499- 505. 11. Kinet, J.F., Metzger, H. , Hakimi, J. , and Kochan, J. (1987) Biochemistry 26, 4605-4610. 12. Kochan, J. , Pettine, L.F., Hakimi, J. , Kisshi, J., and Kinet, J.P. (1988) Nucleic Acids Res 16, 3584- 3594 13. Kuster, H. , Thompson, H. , and Kinet, J.P. (1990) J. Biol. Chem. 265, 6448-6452. 14. Le Coniat, M. , Kinet, J.P., and Berger, R. (1990) Immunogenetics 32, 183-186. 15. Letourneu, 0., Kennedy, I.C.S., Br n , . ., Ortaldo, J.R. , O'Shea, J.J. and Kinet, J.P. (1991) J. Immunol, in press 16. Liu, F.T., Albrandt, K. , and Robertson, M.W. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 5639-5643. 17. Maniatis, T. , Fritsch, E.F., & Sambrook, J. (1982) Molecular Cloning, a Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 18. Miller, J.S., Westin, E.H. , and Schwartz, L.B. (1989) J. Clin. Invest. 84, 1188-1195 19. Miller, L. , Blank, U. , Metzger, H. and Kinet,J.P. (1989) Science 244, 334-337 20. Orloff, D.G., Ra. C, Frank, S.J. , Klausner, R.D. , and Kinet, J.P. (1990) Nature 347, 189-191. 21. Ra, c. , Jouvin, M.H. E. , and Kinet, J.P. (1989) J. Biol. Chem 264, 15323-15327. 22. Ra, c. , Jouvin, M.H.E., Blank, U. , and Kinet, J.P. (1989) Nature 341, 752-754 23. Ravetch J.V. and Kinet, J.P. (1991) Ann. Rev. Immunol. 9, 457-492. 24. Shimizu, A., Tepler, I., Benfey, P.N. , Berenstein, E.H. , Siraganian, R.P., and Leder, P. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 1907-1911. 25. Takebe, Y. , Seiki, M. , Fujisawa, J.-I., Hoy, P., Yokota, K. , Arai, K.-I., Yoshida, M. , Arai, N. (1988) Mol. Cell. Biol. 8, 466-472 26. Tepler, I., Shimizu, A., and Leder, P. (1989) J. Biol. Chem. 264, 5912-5915. 27. Varin-Blank, N. , Metzger, H. (1990) Expression of mutated subunits of the high effinity Mast cell receptor for IgE. J. Biol. Chem. 28. Warner, J.A. , Reshef, A., and MacGlashan, D.W.J. (1987) J. Immunol. Methods 105, 107-110 SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: KINET, Jean-Pierre (ii) TITLE OF INVENTION: ISOLATION, CHARACTERIZATION, AND USE OF THE HUMAN B SUBUNIT OF THE HIGH AFFINITY RECEPTOR FOR IMMUNOGLOBULIN (iii) NUMBER OF SEQUENCES: 34 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Foley & Lardner (B) STREET: 1800 Diagonal Road, Suite 500 (C) CITY: Alexandria (D) STATE: VA (E) COUNTRY: USA (F) ZIP: 22313-0299 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: PatentIn Release #1.0, Version #1.25 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: US 07/869,933 (B) FILING DATE: 16-APR-1992 (C) CLASSIFICATION: (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: BENT, Stephen A. (B) REGISTRATION NUMBER: 29,768 (C) REFERENCE/DOCKET NUMBER: 40399/154 NIHD (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (703)836-9300 (B) TELEFAX: (703)683-4109 (C) TELEX: 899149 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: AAGTACTGGC TATGATTTTT TATCCCATTG 30 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear SUBSTITUTE SHEET ISA/EP (xi) SEQUENCE DESCRIPTION: SEQ ID N0:2: GAATTAATAT GGTCCCTCAG AAACCTAAGG TCTCCTTG 38 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: AAGTACTGGC TATGATTTTT TATCCCATTG 30 (2) INFORMATION FOR SEQ ID NO: : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 17 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO: : Tyr Glu Glu Leu His Val Tyr Ser Pro lie Tyr Ser Ala Leu Glu Asp 1 5 10 15 Thr (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 26 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: misc feature (B) LOCATION: 3 ~ (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 15 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5: GGNGARTASA CATGNARYTC YTCATA 26 SUBSTITUTE SHEET ISA EP (2) INFORMATION FOR SEQ ID NO:6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 26 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 3 (D) OTHER INFORMATION: /note= "N in thiβ sequence represents inosine" (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 15 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6: GGNCTRTASA CATGNARYTC YTCATA 26 (2) INFORMATION FOR SEQ ID NO:7: . (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 23 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7: AATAAAACAA AAAAAAAAAA A?G 23 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 20 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: miεc_feature (B) LOCATION: 9 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8: GARAARTCNG AYGCTCTCTA 20 (2) INFORMATION FOR SEQ ID NO:9: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 26 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear SUBSTITUTE SHEET ISA/EP (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 12 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 21 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (ix) FEATURE: (A) NAME/KEY: misc_feature (B) LOCATION: 24 (D) OTHER INFORMATION: /note= "N in this sequence represents inosine" (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9: AAYCARGARA CNTAYGARAC NYTNAA 26 (2) INFORMATION FOR SEQ ID NO:10: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1174 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (ix) FEATURE: (A) NAME/KEY: CDS CB) LOCATION: 107..880 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10: TACTAAGAGT CTCCAGCATC CTCCACCTGT CTACCACCGA GCATGGGCCT ATATTTGAAG 60 CCTTAGATCT CTCCAGCACA GTAAGCACCA GGAGTCCATG AAGAAG ATG GCT CCT 115 Met Ala Pro 1 GCC ATG GAA TCC CCT ACT CTA CTG TGT GTA GCC TTA CTG TTC TTC GCT 163 Ala Met Glu Ser Pro Thr Leu Leu Cys Val Ala Leu Leu Phe Phe Ala 5 10 15 CCA GAT GGC GTG TTA GCA GTC CCT CAG AAA CCT AAG GTC TCC TTG AAC 211 Pro Asp Gly Val Leu Ala Val Pro Gin Lys Pro Lys Val Ser Leu Asn 20 25 30 35 CCT CCA TGG AAT AGA ATA TTT AAA GGA GAG AAT GTG ACT CTT ACA TGT 259 Pro Pro Trp Asn Arg lie Phe Lys Gly Glu Asn Val Thr Leu Thr Cys 40 45 50 AAT GGG AAC AAT TTC TTT GAA GTC AGT TCC ACC AAA TGG TTC CAC AAT 307 Asn Gly Asn Asn Phe Phe Glu Val Ser Ser Thr Lys Trp Phe His Asn 55 60 65 GGC AGC CTT TCA GAA GAG ACA AAT TCA AGT TTG AAT ATT GTG AAT GCC 355 Gly Ser Leu Ser Glu Glu Thr Asn Ser Ser Leu Asn lie Val Asn Ala 70 75 80 SUBSTITUTE SHEET /EP AAA TTT GAA GAC AGT GGA GAA TAC AAA TGT CAG CAC CAA CAA GTT AAT 403 Lys Phe Glu Asp Ser Gly Glu Tyr Lys Cys Gin His Gin Gin Val Asn 85 90 95 GAG AGT GAA CCT GTG TAC CTG GAA GTC TTC AGT GAC TGG CTG CTC CTT 451 Glu Ser Glu Pro Val Tyr Leu Glu Val Phe Ser Asp Trp Leu Leu Leu 100 105 110 115 CAG GCC TCT GCT GAG GTG GTG ATG GAG GGC CAG CCC CTC TTC CTC AGG 499 Gin Ala Ser Ala Glu Val Val Met Glu Gly Gin Pro Leu Phe Leu Arg 120 125 130 TGC CAT GGT TGG AGG AAC TGG GAT GTG TAC AAG GTG ATC TAT TAT AAG 547 Cys His Gly Trp Arg Asn Trp Asp Val Tyr Lys Val lie Tyr Tyr Lys 135 140 145 GAT GGT GAA GCT CTC AAG TAC TGG TAT GAG AAC CAC AAC ATC TCC ATT 595 Asp Gly Glu Ala Leu Lys Tyr Trp Tyr Glu Asn His Asn lie Ser lie 150 155 160 ACA AAT GCC ACA GTT GAA GAC AGT GGA ACC TAC TAC TGT ACG GGC AAA 643 Thr Asn Ala Thr Val Glu Asp Ser Gly Thr Tyr Tyr Cys Thr Gly Lys 165 170 175 GTG TGG CAG CTG GAC TAT GAG TCT GAG CCC CTC AAC ATT ACT GTA ATA 691 Val Trp Gin Leu Asp Tyr Glu Ser Glu Pro Leu Asn lie Thr Val lie 180 185 190 195 AAA GCT CCG CGT GAG AAG TAC TGG CTA CAA TTT TTT ATC CCA TTG TTG 739 Lys Ala Pro Arg Glu Lys Tyr Trp Leu Gin Phe Phe lie Pro Leu Leu 200 205 210 GTG GTG ATT CTG TTT GCT GTG GAC ACA GGA TTA TTT ATC TCA ACT CAG 787 Val Val lie Leu Phe Ala Val Asp Thr Gly Leu Phe lie Ser Thr Gin 215 220 225 CAG CAG GTC ACA TTT CTC TTG AAG ATT AAG AGA ACC AGG AAA GGC TTC 835 Gin Gin Val Thr Phe Leu Leu Lys lie Lys Arg Thr Arg Lys Gly Phe 230 235 240 AGA CTT CTG AAC CCA CAT CCT AAG CCA AAC CCC Arg Leu Leu Asn Pro His Pro Lys Pro Asn Pro 245 250 ACTCAAGAAA TATTTGCAAC ATTAGTTTTT TTCCAGCATC CAAACACAGC TTGCAATATA CATAGAAACG TCTGTGCTCA ATTAAACTGA GTGAAACTGG TTAAGTGGCA TGTAATAGTA TGAATAAATG AGAGAATGAA TAGATTCATT TATTAGCATT CAATAAAATA AATATAAAAC CATGTAAAAA AAAAAAAAAA (2) INFORMATION FOR SEQ ID NO:11: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 257 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein SUBSTITUTE SHEET ISA/EP (Xi) SEQUENCE DESCRIPTION: SEQ ID NO:ll: Met Ala Pro Ala Met Glu Ser Pro Thr Leu Leu Cys Val Ala Leu Leu 1 5 10 15 Phe Phe Ala Pro Asp Gly Val Leu Ala Val Pro Gin Lys Pro Lys Val 20 25 30 Ser Leu Asn Pro Pro Trp Asn Arg lie Phe Lys Gly Glu Asn Val Thr 35 40 45 Leu Thr Cys Asn Gly Asn Asn Phe Phe Glu Val Ser Ser Thr Lys Trp 50 55 60 Phe His Asn Gly Ser Leu Ser Glu Glu Thr Asn Ser Ser Leu Asn ie 65 70 75 80 Val Asn Ala Lys Phe Glu Asp Ser Gly Glu Tyr Lys Cys Gin His Gin 85 90 95 Gin Val Asn Glu Ser Glu Pro Val Tyr Leu Glu Val Phe Ser Asp Trp 100 105 110 Leu Leu Leu Gin Ala Ser Ala Glu Val Val Met Glu Gly Gin Pro Leu 115 120 125 Phe Leu Arg Cys His Gly Trp Arg Asn Trp Asp Val Tyr Lys Val lie 130 135 140 Tyr Tyr Lys Asp Gly Glu Ala Leu Lys Tyr Trp Tyr Glu Asn His Asn 145 150 155 160 lie Ser lie Thr Asn Ala Thr Val Glu Asp Ser Gly Thr Tyr Tyr Cys 165 170 175 Thr Gly Lys Val Trp Gin Leu Asp Tyr Glu Ser Glu Pro Leu Asn lie 180 185 190 Thr Val lie Lys Ala Pro Arg Glu Lys Tyr Trp Leu Gin Phe Phe lie 195 200 205 Pro Leu Leu Val Val lie Leu Phe Ala Val Asp Thr Gly Leu Phe lie 210 215 220 Ser Thr Gin Gin Gin Val Thr Phe Leu Leu Lys lie Lys Arg Thr Arg 225 230 235 240 Lys Gly Phe Arg Leu Leu Asn Pro His Pro Lys Pro Asn Pro Lys Asn 245 250 255 Asn (2) INFORMATION FOR SEQ ID NO:12: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 222 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: Rat CB) STRAIN: FcRI alpha subunit SUBSTITUTE SHEET ISA/EP (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12: Ala Thr Gin Lys Ser Val Val Ser Leu Asp Pro Pro Trp lie Arg lie 1 5 10 15 Leu Thr Gly Asp Lys Val Thr Leu lie Cys Asn Gly Asn Asn Ser Ser 20 25 30 Gin Met Asn Ser Thr Lys Trp lie His Asn Asp Ser lie Ser Asn Val 35 40 45 Lys Ser Ser His Trp Val lie Val Ser Ala Thr lie Gin Asp Ser Gly 50 55 60 Lys Tyr He Cys Gin Lys Gin Gly Phe Tyr Lys Ser Lys Pro Val Tyr 65 70 75 80 Leu Asn Val Met Gin Glu Trp Leu Leu Leu Gin Ser Ser Ala Asp Val 85 90 95 Val Leu Asp Asn Gly Ser Phe Asp He Arg Cys Arg Ser Trp Lys Lys 100 105 110 Trp Lys Val His Lys Val He Tyr Tyr Lys Asp Asp He Ala Phe Lys 115 120 125 Tyr Ser Tyr Asp Ser Asn Asn He Ser He Arg Lys Ala Thr Phe Asn 130 135 140 Asp Ser Gly Ser Tyr His Cys Thr Gly Tyr Leu Asn Lys Val Glu Cys 145 150 155 160 Lys Ser Asp Lys Phe Ser He Ala Val Val Lys Asp Tyr Thr He Glu 165 170 175 Tyr Arg Trp Leu Gin Leu He Phe Pro Ser Leu Ala Val He Leu Phe 180 185 190 Ala Val Asp Thr Gly Leu Trp Phe Ser Thr His Lys Gin Phe Glu Ser 195 200 205 He Leu Lys He Gin Lys Thr Gly Lys Gly Lys Lys Lys Gly 210 215 220 (2) INFORMATION FOR SEQ ID NO:13: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 232 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: homo sapien (B) STRAIN: FcRI alpha subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13: Val Pro Gin Lys Pro Lys Val Ser Leu Asn Pro Pro Trp Asn Arg He 1 5 10 15 Phe Lys Gly Glu Asn Val Thr Leu Thr Cys Asn Gly Asn Asn Phe Phe 20 25 30 SUBSTITUTE SHEET ISA EP Glu Val Ser Ser Thr Lys Trp Phe His Asn Gly Ser Leu Ser Glu Glu 35 " 40 45 Thr Asn Ser Ser Leu Asn He Val Asn Ala Lys Phe Glu Asp Ser Gly 50 55 60 Glu Tyr Lys Cys Gin His Gin Gin Val Asn Glu Ser Glu Pro Val Tyr 65 70 75 80 Leu Glu Val Phe Ser Asp Trp Leu Leu Leu Gin Ala Ser Ala Glu Val 85 90 95 Val Met Glu Gly Gin Pro Leu Phe Leu Arg Cys His Gly Trp Arg Asn 100 105 110 Trp Asp Val Tyr Lys Val He Tyr Tyr Lys Asp Gly Glu Ala Leu Lys 115 120 125 Tyr Trp Tyr Glu Asn His Asn He Ser He Thr Asn Ala Thr Val Glu 130 135 140 Asp Ser Gly Thr Tyr Tyr Cys Thr Gly Lys Val Trp Gin Leu Asp Tyr 145 150 155 160 Glu Ser Glu Pro Leu Asn He Thr Val He Lys Ala Pro Arg Glu Lys 165 170 175 Tyr Trp Leu Gin Phe Phe He Pro Leu Leu Val Val He Leu Phe Ala 180 185 190 Val Asp Thr Gly Leu Phe He Ser Thr Gin Gin Gin Val Thr Phe Leu 195 200 205 Leu Lys He Lys Arg Thr Arg Lys Gly Phe Arg Leu Leu Asn Pro His 210 215 220 Pro Lys Pro Asn Pro Lys Asn Asn 225 230 (2) INFORMATION FOR SEQ ID NO:14: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 227 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: mouse (B) STRAIN: FcRI alpha subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14: Ala Thr Glu Lys Ser Val Leu Thr Leu Asp Pro Pro Trp He Arg He 1 5 10 15 Phe Thr Gly Glu Lys Val Thr Leu Ser Cys Tyr Gly Asn Asn His Leu 20 25 30 Gin Met Asn Ser Thr Thr Lys Trp He His Asn Gly Thr Val Ser Glu 35 40 45 Val Asn Ser Ser His Leu Val He Val Ser Ala Thr Val Gin Asp Ser 50 55 60 SUBSTITUTE SHEET ISA/EP Gly Lys Tyr He Cys Gin Lys Gin Gly Leu Phe Lys Ser Lys Pro Val 65 70 75 80 Tyr Leu Asn Val Thr Gin Asp Trp Leu Leu Leu Gin Thr Ser Ala Asp 85 90 95 Met He Leu Val His Gly Ser Phe Asp He Arg Cys His Gly Trp Lys 100 105 110 Asn Trp Asn Val Arg Lys Val He Tyr Tyr Arg Asn Asp His Ala Phe 115 120 125 Asn Tyr Ser Tyr Glu Ser Pro Val Ser He Arg Glu Ala Thr Leu Asn 130 135 140 Asp Ser Gly Thr Tyr His Cys Lys Gly Tyr Leu Arg Gin Val Glu Tyr 145 150 155 160 Glu Ser Asp Lys Phe Arg He Ala Val Val Lys Ala Tyr Lys Cys Lys 165 170 175 Tyr Tyr Trp Leu Gin Leu He Phe Pro Leu Leu Val Ala He Leu Phe 180 185 190 Ala Val Asp Thr Gly Leu Leu Leu Ser Thr Glu Glu Gin Phe Lys Ser 195 200 205 Val Leu Glu He Gin Lys Thr Gly Lys Tyr Lys Lys Val Glu Thr Glu 210 215 220 Leu Leu Thr 225 (2) INFORMATION FOR SEQ ID NO:15: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 32 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 9..11 (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 21..32 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15: GAATTAAT ATG AATGAATTT AAG GTC TCC TTG 32 Met Lys Val Ser Leu 1 1 (2) INFORMATION FOR SEQ ID NO:16: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein SUBSTITUTE SHEET ISA/EP (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16; Met 1 (2) INFORMATION FOR SEQ ID NO:17: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17: Lys Val Ser Leu 1 (2) INFORMATION FOR SEQ ID NO:18: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 9..38 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18: GAATTAAT ATG GTC CCT CAG AAA CCT AAG GTC TCC TTG 38 Met Val Pro Gin Lys Pro Lys Val Ser Leu 1 5 10 (2) INFORMATION FOR SEQ ID NO:19: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 10 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19: Met Val Pro Gin Lys Pro Lys Val Ser Leu 1 5 10 (2) INFORMATION FOR SEQ ID NO:20: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 30 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 1..15 SUBSTITUTE SHEET ISA/EP (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20: AAG TAC TGG CTA TGATTTTTTA TCCCATTG 30 Lys Tyr Trp Leu 1 5 (2) INFORMATION FOR SEQ ID NO:21: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 4 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21: Lys Tyr Trp Leu 1 (2) INFORMATION FOR SEQ ID NO:22: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 2545 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 46..786 (ix) FEATURE: (A) NAME/KEY: sig_peptide (B) LOCATION: 46..54 (ix) FEATURE: (A) NAME/KEY: mat_peptide (B) LOCATION: 55..786 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22: ACGTTTCTGT GTAACAATAT CTTTTATTCC TGGATAGTCC AATTA ATG AAA AAA 54 Met Lys Lys -3 ATG GAC ACA GAA AAT AAG AGC AGA GCA GAT CTT GCT CTC CCA AAC CCA 102 Met Asp Thr Glu Asn Lys Ser Arg Ala Asp Leu Ala Leu Pro Asn Pro 1 5 10 15 CAA GAA TCC CCC AGC GCA CCT GAC ATT GAA CTC TTG GAA GCG TCC CCT 150 Gin Glu Ser Pro Ser Ala Pro Asp He Glu Leu Leu Glu Ala Ser Pro 20 25 30 CCT GCA AAA GCT CTA CCA GAG AAG CCA GCC TCA CCC CCA CCA CAG CAG 198 Pro Ala Lys Ala Leu Pro Glu Lys Pro Ala Ser Pro Pro Pro Gin Gin 35 40 45 SUBSTITUTE SHEET ISA EP ACA TGG CAG TCA TTT TTG AAG AAA GAG TTG GAG TTC CTG GGC GTA ACC 246 Thr Trτ> Gin Ser Phe Leu Lys Lys Glu Leu Glu Phe Leu Gly Val Thr 50 55 60 CAA GTT CTG GTT GGT TTG ATA TGC CTT TGT TTT GGA ACA GTT GTC TGC 294 Gin Val Leu Val Gly Leu He Cys Leu Cys Phe Gly Thr Val Val Cys 65 70 75 80 TCC ACA CTC CAG ACT TCA GAC TTT GAC GAC GAA GTG CTT TTA TTA TAT 342 Ser Thr Leu Gin Thr Ser Asp Phe Asp Asp Glu Val Leu Leu Leu Tyr 85 90 95 AGA GCA GGC TAC CCA TTC TGG GGT GCA GTG CTG TTT GTT TTG TCT GGA 390 Arg Ala Gly Tyr Pro Phe Trp Gly Ala Val Leu Phe Val Leu Ser Gly 100 105 110 TTT TTG TCA ATT ATG TCC GAA AGG AAA AAC ACA CTG TAT CTG GTG AGA 438 Phe Leu Ser He Met Ser Glu Arg Lys Asn Thr Leu Tyr Leu Val Arg 115 120 125 GGC AGC CTG GGA GCA AAC ATT GTC AGC AGC ATC GCT GCA GGC TTG GGG 486 Gly ser Leu Gly Ala Asn He Val Ser Ser He Ala Ala Gly Leu Gly 130 135 140 ATC GCC ATA TTG ATT CTC AAT CTG AGC AAC AAC TCC GCT TAT ATG AAC 534 He Ala He Leu He Leu Asn Leu Ser Asn Asn Ser Ala Tyr Met Asn 145 150 155 160 TAC TGC AAG GAT ATA ACC GAA GAC GAT GGT TGC TTC GTG ACT TCT TTC 582 Tyr Cys Lys Asp He Thr Glu Asp Asp Gly Cys Phe Val Thr Ser Phe 165 170 175 ATC ACA GAA CTG GTG TTG ATG TTG CTG TTT CTC ACC ATC CTG GCC TTT 630 He Thr Glu Leu Val Leu Met Leu Leu Phe Leu Thr He Leu Ala Phe 180 185 190 TGC AGT GCC GTG CTG CTC ATT ATC TAT AGG ATT GGA CAA GAA TTT GAG 678 Cys Ser Ala Val Leu Leu He He Tyr Arg He Gly Gin Glu Phe Glu 195 200 205 CGT AGT AAG GTC CCC GAT GAC CGT CTC TAT GAA GAA TTA CAT GTG TAT 726 Arg Ser Lys Val Pro Asp Asp Arg Leu Tyr Glu Glu Leu His Val Tyr 210 215 220 TCA CCA ATT TAC AGT GCG TTG GAA GAC ACA AGG GAA GCG TCC GCA CCA 774 Ser Pro He Tyr Ser Ala Leu Glu Asp Thr Arg Glu Ala Ser Ala Pro 225 230 235 240 GTG GTT TCA TAAGAATCAA GGGGCCAGGA CAATCTGATT CCAGTCTAGT 823 Val Val Ser SUBSTITUTE SHEET ISA/EP TTATCTAATT CATGGGTATA TTCACTAATA CAGTTGTTGC TCAGTGGTGT TTACTACTTG 1363 GTGGGTAGTA GGTAATAGAG AACATTATTA AATCATTCAG TGTAGTGAGA TGCATAGGTA 1423 AAATCAGGGA CACTGTGAGT GTGTATATCT TTTGGTAAGA CATGTGTGAA AATGAAGAAT 1483 AAACTGATGA AGACTTGAGC TGGAAAGTAG TCAATGGGAA TGACAAGAAA TGATTGTGTA 1543 TAACACTTGT AGATAAATAA CTACCAACAA TTGGTAGAGA TTGCCATGTA TGCCTAAAAT 1603 CTCCCAGCCC AAGGCCAGCC TCTGTTACAC AGTGAGTTAG AGGCCAGTCT GGGCTACACA 1663 AGATCATACA TCAAAGGACG AAAGAAGATG TTGGTTCAAA CTGTTAACAC AGTAAGGGAT 1723 ATTTAAACAA ACAGAAGTTT GACTGATATA TTGAGTGCTT GAGTTTTTAA TAAAACTGAA 1783 TGAATAACAT TGCGGGGGAG GGGAGCAGTG ATGCAGAAGT CTGGATGATG GAGGAGTAGC 1843 AGAATCAG T GAAACATTGA AACGTATTTC CAGACTTTTG TTCTGAGATG GTTATAAGAG 1903 CAATCACCAT TAAATGAAGA AGGTCAAGAC ACCAAAAGAA TTATTTTGAG ATAGAATTAA 1963 GACAGTCAAA ATCCACATGC CTATACTTAG AAGGTGAAGT AAGGATCAAA AGTAGAAAGC 2023 CTAACGATTA GTTGGAAAAG CATATTACGT TAGGCAGCAG ATGTCTATAG TGGAGAAAAG 2083 TTAAACAAGG AGAAATAATG AACCACCAGA GACTCTACAT GTTGGTTTGG GAAATAAGAG 2143 AAAATAGCAA TTCTAAACGA ATGCAAACTC TGAAGAAGCA TTTCCCAAAG GGTGTGGGCA 2203 GAGGACCAGA ACATTTGCAA ATGTACCTAG AGAGCAAACC TGAATAGGAG GTAAAATGGG 2263 GGAAAAGCAG CTAAGAAAAT GATTTTGTTG CTGTTATTTA GATTTTAAAA GAAACAAAAA 2323 GAGTCATTAA AAATCTGTTT GCTGGGATCA GTTATTGTGT TCTCTGTGTA TGTCCAAAGT 2383 ACAGGTAACT TTTCTAAATC TTCCTGTAAG GCTCACCTCA TATGTCTCTT CACATAGCCA 2443 CACCCTTGAT TCACAGTTAC TCTACCACAG TAGTAAACTG TGCTTGTGGT CTCCCTTATG 2503 TATCTTCACT AGTGTTTATA AAATAAATCA GAATTATTTA AA 2545 (2) INFORMATION FOR SEQ ID NO:23: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 246 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23: Met Lys Lys Met Asp Thr Glu Asn Lys Ser Arg Ala Asp Leu Ala Leu -3 1 5 10 Pro Asn Pro Gin Glu Ser Pro Ser Ala Pro Asp He Glu Leu Leu Glu 15 20 25 Ala Ser Pro Pro Ala Lys Ala Leu Pro Glu Lys Pro Ala Ser Pro Pro 30 35 40 45 Pro Gin Gin Thr Trp Gin Ser Phe Leu Lys Lys Glu Leu Glu Phe Leu 50 55 60 SUBSTITUTE SHEET ISA/EP Gly Val Thr Gin Val Leu Val Gly Leu He Cys Leu Cys Phe Gly Thr 65 70 75 Val Val Cvs Ser Thr Leu Gin Thr Ser Asp Phe Asp Asp Glu Val Leu 80 85 90 Leu Leu Tyr Arg Ala Gly Tyr Pro Phe Trp Gly Ala Val Leu Phe Val 95 100 105 Leu Ser Gly Phe Leu Ser He Met Ser Glu Arg Lys Asn Thr Leu Tyr 110 115 120 125 Leu Val Arg Gly Ser Leu Gly Ala Asn He Val Ser Ser He Ala Ala 130 135 140 Gly Leu Gly He Ala He Leu He Leu Asn Leu Ser Asn Asn Ser Ala 145 150 155 Tyr Met Asn Tyr Cys Lys Asp He Thr Glu Asp Asp Gly Cys Phe Val 160 165 170 Thr Ser Phe He Thr Glu Leu Val Leu Met Leu Leu Phe Leu Thr He 175 180 185 Leu Ala Phe Cys Ser Ala Val Leu Leu He He Tyr Arg He Gly Gin 190 195 200 205 Glu Phe Glu Arg Ser Lys Val Pro Asp Asp Arg Leu Tyr Glu Glu Leu 210 215 220 His Val Tyr Ser Pro He Tyr Ser Ala Leu Glu Asp Thr Arg Glu Ala 225 230 235 Ser Ala Pro Val Val Ser 240 (2) INFORMATION FOR SEQ ID NO:24: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 286 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (ii) MOLECULE TYPE: CDNA (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 1..18 (xi) SEQUENCE DESCRIPTION: SEQ ID N0:24: GTG AGA ACA TAT CTG TAATTGTTTC TGAAATGATG CTAACCAGAG ATTTTATTTT 55 Val Arg Thr Tyr Leu 1 5 AATCAAAGAC AACTAATTTT CTTTTAATCA AGTGCTTATC TCTAGCCTTT CAATAATATC 115 TACAGTTCTT CATTTATATG CACATAGCCA TCTATAAATG TAGTTTCCAA AGCACTCTCT 175 ACATATACTC ATTAACAAGA GCAAATACAC TCACCACAGT TAACTATGGT TTAACCCATT 235 ACTATACTTT TATTGACTGA AAACCTTGAG ACTGTACAAA AAAAAAAAAA A 286 SUBSTITUTE SHEET ISA/EP (2) INFORMATION FOR SEQ ID NO:25: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:25: Val Arg Thr Tyr Leu 1 5 (2) INFORMATION FOR SEQ ID NO:26: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 586 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: double (D) TOPOLOGY: linear (vi) ORIGINAL SOURCE: (A) ORGANISM: rat (B) STRAIN: FcRI gamma subunit (ix) FEATURE: (A) NAME/KEY: sig_peptide (B) LOCATION: 23..76 (i ) FEATURE: (A) NAME/KEY: mat_peptide (B) LOCATION: 77..283 (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 23..283 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:26: AGCGCTGCAG CCCCCGCCCA GG ATG ATC CCA GCG GTG ATC TTG TTC TTG CTC 52 Met He Pro Ala Val He Leu Phe Leu Leu -18 -15 -10 CTT TTG GTG GAA GAA GCA GCT GCC CTA GGA GAG CCG CAG CTC TGC TAT 100 Leu Leu Val Glu Glu Ala Ala Ala Leu Gly Glu Pro Gin Leu Cys Tyr -5 1 5 ATC CTG GAT GCC ATC CTG TTT TTG TAT GGT ATT GTC CTT ACC CTG CTC 148 He Leu Asp Ala He Leu Phe Leu Tyr Gly He Val Leu Thr Leu Leu 10 15 20 TAC TGT CGA CTC AAG ATC CAG GTC CGA AAG GCA GAC ATA GCC AGC CGT 196 Tyr Cys Arg Leu Lys He Gin Val Arg Lys Ala Asp He Ala Ser Arg 25 30 35 40 GAG AAA TCA GAT GCT GTC TAC ACG GGC CTG AAC ACC CGG AAC CAG GAG 244 Glu Lys Ser Asp Ala Val Tyr Thr Gly Leu Asn Thr Arg Asn Gin Glu 45 50 55 ACA TAT GAG ACT CTG AAA CAT GAG AAA CCA CCC CAA TAGCTTTACA 290 Thr Tyr Glu Thr Leu Lys His Glu Lys Pro Pro Gin 60 65 ACACGTGTTC TCAGCTGCAT TCCTTTTCCG CTTTTAATTC TCTCCTCGCC CTCATGATTG 350 SUBSTITUTE SHEET ISA/EP ACGTGGCTGT GCTACCTCCG TGCTTCTGGA ACTAGCTGAC CTTATTCCCA GAACCATGCT 410 AGGCTCTAAA TCAATGTCCC CATATCCACC AAAGACTTAC TCACTGACAT TTCTCTTCTC 470 CCATCCTCCT TTGCTTCATT CCTCTTTCCT TCCCTGATCC TCTGTGCTCA CTAAACAATG 530 GGAAGGGATT ACCCCCCAAT AAAGCTGCCA GAGATCACGC TCAAAAAAAA AAAAAA 586 (2) INFORMATION FOR SEQ ID NO:27: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 86 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein ( i) SEQUENCE DESCRIPTION: SEQ ID NO:27: Met He Pro Ala Val He Leu Phe Leu Leu Leu Leu Val Glu Glu Ala -18 -15 -10 -5 Ala Ala Leu Gly Glu Pro Gin Leu Cys Tyr He Leu Asp Ala He Leu 1 5 10 Phe Leu Tyr Gly He Val Leu Thr Leu Leu Tyr Cys Arg Leu Lys lie 15 20 25 30 Gin Val Arg Lys Ala Asp He Ala Ser Arg Glu Lys Ser Asp Ala Val 35 40 45 Tyr Thr Gly Leu Asn Thr Arg Asn Gin Glu Thr Tyr Glu Thr Leu Lys 50 55 60 His Glu Lys Pro Pro Gin 65 (2) INFORMATION FOR SEQ ID NO:28: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 222 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (B) STRAIN: alpha subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:28: Ala Thr Gin Lys Ser Val Val Ser Leu Asp Pro Pro Trp He Arg He 1 5 10 15 Leu Thr Gly Asp Lys Val Thr Leu He Cys Asn Gly Asn Asn Ser Ser 20 25 30 Gin Met Asn Ser Thr Lys Trp He His Asn Asp Ser He Ser Asn Val 35 40 45 Lys Ser Ser His Trp Val lie Val Ser Ala Thr He Gin Asp Ser Gly 50 55 60 SUBSTITUTE SHEET ISA/EP Lys Tyr He Cys Gin Lys Gin Gly Phe Tyr Lys Ser Lys Pro Val Tyr 65 70 75 80 Leu Asn Val Met Gin Glu Trp Leu Leu Leu Gin Ser Ser Ala Asp Val 85 90 95 Val Leu Asp Asn Gly Ser Phe Asp He Arg Cys Arg Ser Trp Lys Lys 100 105 110 Trp Lys Val His Lys Val He Tyr Tyr Lys Asp Asp He Ala Phe Lys 115 120 125 Tyr Ser Tyr Asp Ser Asn Asn He Ser He Arg Lys Ala Thr Phe Asn 130 135 140 Asp Ser Gly Ser Tyr His Cys Thr Gly Tyr Leu Asn Lys Val Glu Cys 145 150 155 160 Lys Ser Asp Lys Phe Ser He Ala Val Val Lys Asp Tyr Thr He Glu 165 170 175 Tyr Arg Trp Leu Gin Leu He Phe Pro Ser Leu Ala Val He Leu Phe 180 185 190 Ala Val Asp Thr Gly Leu Trp Phe Ser Thr His Lys Gin Phe Glu Ser 195 200 205 He Leu Lys He Gin Lys Thr Gly Lys Gly Lys Lys Lys Gly 210 215 220 (2) INFORMATION FOR SEQ ID NO:29: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 243 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (B) STRAIN: beta subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:29: Met Asp Thr Glu Asn Lys Ser Arg Ala Asp Leu Ala Leu Pro Asn Pro 1 5 10 15 Gin Glu Ser Pro Ser Ala Pro Asp He Glu Leu Leu Glu Ala Ser Pro 20 25 30 Pro Ala Lys Ala Leu Pro Glu Lys Pro Ala Ser Pro Pro Pro Gin Gin 35 40 45 Thr Trp Gin Ser Phe Leu Lys Lys Glu Leu Glu Phe Leu Gly Val Thr 50 55 60 Gin Val Leu Val Gly Leu He Cys Leu Cys Phe Gly Thr Val Val Cys 65 70 75 80 Ser Thr Leu Gin Thr Ser Asp Phe Asp Asp Glu Val Leu Leu Leu Tyr 85 90 95 Arg Ala Gly Tyr Pro Phe Trp Gly Ala Val Leu Phe Val Leu Ser Gly 100 105 110 SUBSTITUTE SHEET ISA/EP Phe Leu Ser lie Met Ser Glu Arg Lys Asn Thr Leu Tvr Leu Val Arg 115 120 125 Gly Ser Leu Gly Ala Asn He Val Ser Ser He Ala Ala Gly Leu Gly 130 135 140 He Ala He Leu He Leu Asn Leu Ser Asn Asn Ser Ala Tyr Met Asn 145 150 155 160 Tyr Cys Lys Asp He Thr Glu Asp Asp Gly Cys Phe Val Thr Ser Phe 165 170 175 He Thr Glu Leu Val Leu Met Leu Leu Phe Leu Thr He Leu Ala Phe 180 185 190 Cys Ser Ala Val Leu Leu He He Tyr Arg He Gly Gin Glu Phe Glu 195 200 205 Arg Ser Lys Val Pro Asp Asp Arg Leu Tyr Glu Glu Leu His Val Tyr 210 215 220 Ser Pro He Tyr Ser Ala Leu Glu Asp Thr Arg Glu Ala Ser Ala Pro 225 230 235 240 Val Val Ser * (2) INFORMATION FOR SEQ ID NO:30: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 62 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (B) STRAIN: gamma subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:30: Leu Gly Glu Pro Gin Leu Cys Tyr He Leu Asp Ala He Leu Phe Leu 1 5 10 15 ■ Tyr Gly He Val Leu Thr Leu Leu Tyr Cys Arg Leu Lys He Gin Val 20 25 30 Arg Lys Ala Asp He Ala Ser Arg Glu Lys Ser Asp Ala Val Tyr Thr 35 40 45 Gly Leu Asn Thr Arg Asn Gin Glu Thr Tyr Glu Thr Leu Lys 50 55 60 (2) INFORMATION FOR SEQ ID NO:31: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 11298 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (vi) ORIGINAL SOURCE: (A) ORGANISM: homo sapien (B) STRAIN: FcRI beta SUBSTITUTE SHEET ISA/EP (xi) SEQUENCE DESCRIPTION: SEQ ID NO:31: AAGCTTTTCA AAGGTGCAAT TGGATAACTT CTGCCATGAG AAATGGCTGA ATTGGGACAC 60 AAGTGGGGAC AATTCCAGAA GAAGGGCACA TCTCTTTCTT TTCTGCAGTT CTTTCTCACC 120 TTCTCAACTC CTACTAAAAT GTCTCATTTT CAGGTTCTGT AAATCCTGCT AGTCTCAGGC 180 AAAATTATGC TCCAGGAGTC TCAAATTTTC TTATTTCATA TTAGTCTTTA TTTAGTAGAC 240 TTCTCAATTT TTCTATTCAT CACAAGTAAA AGCCTGTTGA TCTTAATCAG CCAAGAAACT 300 TATCTGTCTG GCAAATGACT TATGTATAAA GAGAATCATC AATGTCATGA GGTAACCCAT 360 TTCAACTGCC TATTCAGAGC ATGCAGTAAG AGGAAATCCA CCAAGTCTCA ATATAATAAT 420 ATTCTTTATT CCTGGACAGC TCGGTTAATG AAAAAATGGA CACAGAAAGT AATAGGAGAG 480 CAAATCTTGC TCTCCCACAG GAGCCTTCCA GGTAGGTACA AGGTATTATT TTTTTCTACC 540 CTCAGTCACT TGTGGCAGGG GAAGTCATAG TCACGGTGCT TAGGAGATGA AACTTTATTG 600 ATTTAGGCAT GGATCCATCT AGTTTAATTA ATATATTGGG TATGAGGAAG CTACTTGCTG 660 TACTTTCCAT GTGGTTCTCT CTCCCTGGAG AGGAACATTT TTACTCAGCT TGCAAACTGG 720 AAATAGATTT TCTCACATTA GAAGCTCATT TTCTGGGTAT GAGACAGGAG AGTTCATACT 780 GTGTATGTAG ATCTCTGGCT TCTGGGTCTG ACATGTGCTG AGGGACACAT ATCCTTCACA 840 CATGCTTTTA TAAATACTTG ATAAAGTAAC CTGCTTCTTG ATTGGTCTTT ATAATCCATA 900 AGCTGTGGGA TGCTTCTCTG AAGATGAAAA TAGTAATAGA GTCCCATCTA GCTATTCAAA 960 GCCATTCCTT CATTGTATTC TGTGCACATG AAGTTGGGGT TTGTTACTGA CAAAATATAT 1020 TCAGATACAT TTCTATGTTA AAAGGATTGT GAGATGCATA GGTAAATGTG TTTATTTTCA 1080 GTTTTACTTG TCAACATAGA 'I'GAATGAGAA AGAACTTGAA AGTAACACTG GATTAAGAAT 1140 AGGAAAATTT GGCATGGATT TTGCTCCATT TTGTCCCATC TAATCACTTG GATAGTGTTC 1200 AGGTGTTCTT GGTCAGTTAC TTGGATGCTC TGAGCTTTAG TTTCTTGGTG ATTACAATGA 1260 AGATTTGAAT TACAGGATGG CTTTGAAAAA ATAAACAAAA CTCCCCTTTC TGTCTGTCGA 1320 GAATGTTGCA CAGGGAGTTA CAGAATGTTC TCATGACTGA ATTGCTTTTA AATTTCACAG 1380 TGTGCCTGCA TTTGAAGTCT TGGAAATATC TCCCCAGGAA GTATCTTCAG GCAGACTATT 1440 GAAGTCGGCC TCATCCCCAC CACTGCATAC ATGGCTGACA GTTTTGAAAA AAGAGCAGGA 1500 GTTCCTGGGG GTGAGTGAGC CTCCTCCAAC TTTGACTAGA GTAAGGGTTG GGTCTAGAAA 1560 AGAATATTGA GTTGCATCAA CTGTTTTCCC ACTTGGATTC ATGAGAGGTG TTAGGTCCTT 1620 TAAAAAACAT GGTAGATAAA GAGTTGACAC TAACTGGGTC CTTTTGGGAA GAGCCAGAAG 1680 CATTTCCTCA TAAAGACTTT AAATTGCTAG GACGAGAATG GCCAACAGGA GTGAAGGATT 1740 CATAACTTTA TCTTTACTTA GATGTAAAGA ACAATTACTG ATGTTCAACA TGACTACATA 1800 CATAAAGGCG CATGGAGAAA AGTATTGGCC TTCCATGCAT TAGGTAGTGC TTGTATCAAT 1860 TCTTATAGTG GCTAGGGTAT CCTGGAAAAT CTTACGTGTG GATCATTTCT CAGGACAGTC 1920 TAGGACACTA ACGCAGTTTC TCATGTTTGG CTTCTATTAT TAAAAAATGA TACAATCTCG 1980 SUBSTITUTE SHEET ISA/EP GGAAAATTTT TTTGATTTTC ATGAAATTCA TGTGTTTTTC TATAGGTAAC ACAAATTCTG 2040 ACTGCTATGA TATGCCTTTG TTTTGGAACA GTTGTCTGCT CTGTACTTGA TATTTCACAC 2100 ATTGAGGGAG ACATTTTTTC ATCATTTAAA GCAGGTTATC CATTCTGGGG AGCCATATTT 2160 GTGAGTATAT ATCTATAATT GTTTCTGAAA TAACACTGAA CATAGGTTTT TCTCTTTCTC 2220 AGATCTAACC AGTTGTTTAT TCCCAGTATT AAGATGATAT TTATAATTCT TAATTATAAA 2280 TATATGTGAG CATATATAAC ATAGATATGC TCATTAACAA CAACAAAAGA TTCTTTTTAC 2340 AATTAACGGT GGGTTAAACA TTTAGCCCAC AGTTTTATCC CATGAGAAAC CTGAATCTAA 2400 TACAAGTTAA ATGACTTGCC TAAGGGCCAC TTGACTAATA GTAATTGAAC CTAAACTTTC 2460 AGAATCCAAC TCCAGGAACA TACTTCTAGC ACTATTCATC AATAAAGTTA TATGATAAAT 2520 ACATACAACT TTATCTGTCA ACTAAAAATA ACAACAGAGG CTGGGCATGG TGGCTCACAC 2580 CCGTAATCCC AGCACTTTGG GAGGCTGAGG CAGGTGGATC ACCTGAGGTC AGGAGTTTGA 2640 GACCAGCCTG ACCAACATGG TGAAACCTCA TCTCTACTAA ATATAAAAAA TTAGCTGAGT 2700 GTGATAGTGC ATACCTGTAA TCCAGCTACT TAAGAGGCTG AGGCAGGAGG CTTGTTTGAA 2760 CCTGGAAGGC AGAGGTTGCA GTGAGCTGAG ATTGTGCCAT TGCACTCCAG CCTGGGCAAT 2820 AAGTGCGAAC TCTGTCTCAA AATAATAATA ATAATAATAG AAAATAAAGT TGTCTTCATG 2880 AAAAATGAGG AAAGAGATTG CTGGGGTGAG AAACATTAAG ATCAATGGGC ATATGGTGAC 2940 CTTCTATGCC CTAGAAACTC TTTTANGGTA TTTTCTCCTG GTATCTCTTT TACNCATCGT 3000 TCTATCTGGA AAAATAGGTG GATGAGTGAG ATAATAACGG TATATACTTT TTAAAGGTCT 3060 AATTGACATA TATAAATTGC AAGTATTTCA GATGTCAATT TGCTAACCTT GACACACATA 3120 GACACACATG AAAACATCAC CACATTAATA CAATGTATGT ATCCATCATT CCAAAAGCTT 3180 CCCTGTGTAT CTTTGTAACT CTTTCTTCCT CCCTCCACTC CTTGTCCTCT CGTTCCCAAG 3240 AAAACATTGA TCTGCTTCCT GTGAATATAA ATTAACTTAC ATTTTTTAGA GCTTTATATA 3300 AGTATGTTCT CTTTACTGTT TGTCTTCCTT CGCTGCACAG TTATTTTGAG ATTCTTCAAG 3360 TTTTTTCTTT ATATCGATAC TTCATTCACA AGAATATATT TTAATTCTAG ACTATGTCAC 3420 ATTGACTTTG TCGTCTGCTA AATCCTTAGT GCTCAGATGA CTTGTTCAGG ACTCTCCTTG 3480 AACCTGTACC TCTGTTANAT TGAAACTTGT CTCTACTGTC TTTTTATTTC AAACACAGCT 3540 TATTAGGTGT CTCTCAACCC ATCAAACNCA CAATCTGAGT CTTTAGGAGA TTGCTTTGAA 3600 TTTGTGCTAT TGACTTATAT NTATATNAAA TNTGTAAATG TTTGGTAAAA ATATCATCAT 3660 GTACNTTTTC ATAATTACGC TATNTNCACA TGATATATGT CAGACTCTGG AAATATGCAT 3720 GCCACAGACA CGTGTTTCTT GCCTAAAGGG GCTGATGGAA GACNCACATA CNAATAGACG 3780 ATTGCAGTAG AATGAGAGTG GTGGTCTAAN CAGTACATGT CCTGATGTTG CTCGGACAGT 3840 TACTACNCCA AGAGTACCCC CTGCATTGTC AGGGTTAGCA TCTCCTGGAA GCCTCATGTA 3900 AATGAAGAAT TTCATGCTCC ATCCAGGACC TAATGAATAA GAATCTGCAT TTTAGCAAGA 3960 CCCTCATATG ATTCATATAC ACTTTTTTTT TTTTTTTTTA GATGGAGTCT CACTCTTGTC 4020 SUBSTITUTE SHEET ISA/EP GCCCAGGCTG GAGTGCAATG GCATGATCTT GGCTCACTGC AACCTCTGCC TCCCGGGTTC 4080 AAGTGATTCT CCTGTCTCAG CCTCCCTAGT AGCTGGGACT ACAGGTGCAT GCCACAGTGG 4140 CTGGCTAATT TTTGTATTTT TAGTAGAGAC AGGGTTTCAC CATTTTGGTC AGGCTGGTCT 4200 TGAACTCATG ACCTCCGGTG ATTCCCCCGC CTCGGCTTCC CAAAGTGCTG GGATTACAGA 4260 CATGAGCCAC CACACCCGCC TTATTCGTAT ACNCATTTAA TTCTGAGAAG CACTCTATAG 4320 AAAATAAGAA TAAGAAAATA TTGGGCTCAC AGGTGACATT AATAAGTAAC TTTATCGAGT 4380 ACCCCAAATT TTACCTATGT TTGGAAGATG GGGTTAAAAG GACACATTGA AAACAAGAAC 4440 TCATTGTGGC TTTTTTTTCC TCCTTTTTGA ACAGTTTTCT ATTTCTGGAA TGTTGTCAAT 4500 TATATCTGAA AGGAGAAATG CAACATATCT GGTGAGTTGC CCGTTTCTGT CTTTGTCCAT 4560 CCTTGAAAAG ATAAGAAGAA CAGAGTTTTA AGAGTCTTAA GGGAAACACA TCTTTGTCTC 4620 CTATATTACT TGTGAATGTG GATATATGAT TTTGTTTCAA TCTATTTTGT GTCCTAAGGC 4680 TTTTTGCAAC AGAAGTTGGA TATATCATTA GAAACATAAA TTGTACCATT TAACATACAT 4740 GAAGTTTATG TTTACCTTGA CGTTCTTCTA AAAAGTGTCC TACACCGGCA TTGTCCTTGT 4800 AGGCATATTC ACATGATCAA ATAAAATAAT TAGTTTTCAA TTAAGGAGAA TATTTGAGGA 4860 AAGACCGTAC GTGTTCATGT GGTTCCTGAA GGCAGTCCAG TGAGAAAGTA ATATATGCTT 4920 CATTAAACAA TGCGGACATT TTCAGGGTTT CCCTTTTTAA CCAAAATTTG GAAGCAATGT 4980 GGAATTTACT GGATGCATCC AGCCCTGAAA TGAAGATAGG TTTATTGAAT GTGCCAGCAA 5040 GTGCAGGCCC AGGTCTGAGT GTTCTTCATT ATTATCAGGT GAGAGGAAGC CTGGGAGCAA 5100 ACACTGCCAG CAGCATAGCT GGGGGAACGG GAATTACCAT CCTGATCATC AACCTGAAGA 5160 AGAGCTTGGC CTATATCCAC ATCCACAGTT GCCAGAAATT TTTTGAGACC AAGTGCTTTA 5220 TGGCTTCCTT TTCCACTGTA TGTATTTTTT TTTGTGTGGG AAGACTAAGA TTCTGGGTCC 5280 TAATGTAAGT AAGAAGCCCT CTTCTCCTGT TCCATGAACA CCATCCTTTT CTGTAACTTC 5340 TATTACACAG TATAGTGGTT CTGTAAGTTC ACACAGCCCA GGGAGATGCT GGCTGCCCAC 5400 TCCCCTCAAC CCAGGCAAAT TCCTCGGGGT TAAAGTTATC TACTGCAAGT GACGATCTCT 5460 GGGTTTTTCT GTGCCTGTGT TTGTGTGTGT GTGTGTGTGT GTGTGTGTGT GTATGTGTCA 5520 CTTTAAAAGG ACTGGTCAGA TGGTAGGGAG ATGAAAACAG GAGATGCTAT AAGAAAATAA 5580 ACTTTTGGGG CGAATACCAA TGTGACTCTT TTTGTTTGTC ATTTGTTGCT GTTCAATAGG 5640 AAATTGTAGT GATGATGCTG TTTCTCACCA TTCTGGGACT TGGTAGTGCT GTGTCACTCA 5700 CAATCTGTGG AGCTGGGGAA GAACTCAAAG GAAACAAGGT AGATAGAAGC CCGATATAAA 5760 ATCTTGAATG ACAGGTTAAC GAATTGGAGC TTTATTCCTT AAAATATGGC CTGGGTTTTC 5820 TGAAACATTT CTTCCAGAAA ATAGTTTCTC CAAGTTTTAT TACTTTGGTT TACAAATCTC 5880 ACATTTAAAT CACATTTTAT ACCATAAGTA GCACACATTT CATAATATTC CTCTGAATGA 5940 GGGTTGGGAT AATAGGACTG ATATGTTAGA AATGCCTTAA AGTGTGTGGA GCATGAGAGA 6000 TGGATGTACA GAAGGCTTGT GAGGAAACCA CCCAGGTATC TGGCCTTGTT TTCTGCCCCA 6060 SUBSTITUTE SHEET GAACTAGCCG CCTATTCCTG TTTCTGTTTT ATTCCTTTGT TTCTTGACTT TTCCTTTCCA 612.0 ACTTGCTCTA AAACCTCAGT TTTCTTTCCT TTCTGATTCA- TGACTACCAA ATGTTTTCAC 6180 TTGCCTCACC CGTCCATTAC ACCTTTGATA AGAACCACCA GACCTTGTGC TCATGTACTT 6240 GCCCATGTCT GATGGAAGAA ACATACTCTC TCCATCTGTC CACTTTCCTG AGGCATTCAA 6300 GTCTAGCCAC CTTTTAAAAT CACTCTCCTC CAGGCTGGGC ACGGTGTCAC GCCTGTAATC 6360 TCAGCACTTT GTGAGGCTGA GGAGGGCGGA TCACTTGAAG TCAGGAGTTC AAAACCAGCC 6420 TGGCCAAATG GCAAAACCAA ATCTTCTTCA ATTATAACCA AATCTTAAAC CAAATCTCTA 6480 CTAAAAAATA CAACAAAACA AAACAACAAC AACAAAAACA GAAAAGGAAA CATTAGCCCA 6540 GCGTGGTGGC AGGTACCTGA GGTTCCAGAT ACTTGGGAGG CTGAAGCAGG AGAATCGCTT 6600 GAGCCCAAGA GATGGAGGTT GCAGTGAGCC GAGATCATGC CACTGCACCA CAGCCAGGGT 6660 GACAGAGCCA TACTTCCCAG CACATTGGGA GGCCAAAGCT GAAGAATAAT TTGAGGTGAG 6720 GATTTGGAGA CCAGCCTGGC CAACATGGTG AAACTCCGTC TGTACTAAAA ATATAAAACT 6780 TAGTGGGGCA TGGGGGCACA CACCTGTAAT TTCAGCTACT TAGGAGGCTG AGGCAGGAGA 6840 ATTGCTTGAA CCCGGGAGGC GGAAGTTGCA GTGAGCCAAG ATCGTGGCCA CTGCACTCCA 6900 GCCTGGGTGA CATAGTGAGA TTCTGTCTCA AAAAAAATAA AAGAAATTTA AAAAATCACT 6960 CTCTTCCAAA GATAGATAAA TAAGACAGCA GATATACTAA GGAATAACCT CACCAACTTG 7020 TCATTGACTG ACATGATTTC TTTTGGCCCA CTTGGCCAGG TAGTCTCiGTT TGGTTTTCTG 7080 GAAATGAAAG AAATAATCAG AGTTTAATGA CAGAGAGCGT GAGACCCAGA AAGACAAAAG 7140 TAGATGAGGT AAGTCTCTTG AGCGAGACTT CTAGGGATGG GAAATTTGTG GTGATTGATA 7200 TGAAATGATT TTTCCCTTAT CAGGTTCCAG AGGATCGTGT TTATGAAGAA TTAAACATAT 7260 ATTCAGCTAC TTACAGTGAG TTGGAAGACC CAGGGGAAAT GTCTCCTCCC ATTGATTTAT 7320 AAGAATCACG TGTCCAGAAC ACTCTGATTC ACAGCCAAGG ATCCAGAAGG CCAAGGTTTT 7380 GTTAAGGGGC TACTGGAAAA ATTTCTATTC TCTCCACAGC CTGCTGGTTT TACATTAGAT 7440 TTATTCGCCT GATAAGAATA TTTTGTTTCT GCTGCTTCTG TCCACCTTAA TATGCTCCTT 7500 CTATTTGTAG ATATGATAGA CTCCTATTTT TCTTGTTTTA TATTATGACC ACACACATCT 7560 CTGCTGGAAA GTCAACATGT AGTAAGCAAG ATTTAACTGT TTGATTATAA CTGTGCAAAT 7620 ACAGAAAAAA AGAAGGCTGG CTGAAAGTTG AGTTAAACTT TGACAGTTTG ATAATATTTG 7680 GTTCTTAGGG TTTTTTTTTT TTTTAGCATT CTTAATAGTT ACAGTTGGGC ATGATTTGTA 7740 CCATCCACCC ATACCCACAC AGTCACAGTC ACACACACAT ATGTATTACT TACACTATAT 7800 ATAACTTCCT ATGCAAATAT TTTACCACCA GTCAATAATA CATTTTTGCC AAGACATGAA 7860 GTTTTATAAA GATCTGTATA ATTGCCTGAA TCACCAGCAC ATTCACTGAC ATGATATTAT 7920 TTGCAGATTG ACAAGTAGGA AGTGGGGAAC TTTTATTAAG TTACTCGTTG TCTGGGGAGG 7980 TAAATAGGTT AAAAACAGGG AAATTATAAG TGCAGAGATT AACATTTCAC AAATGTTTAG 8040 TGAAACATTT GTGAAAAAAG AAGACTAAAT TAAGACCTGA GCTGAAATAA AGTGACGTGG 8100 SUBSTITUTE SHEET ISA/EP ΛAATGGAAAT AATGGTTATA TCTAAAACAT GTAGAAAAAG AGTAACTGGT AGATTTTGTT 81.60 AACAAATTAA AGAATAAAGT TAGACAAGCA ACTGGTTGAC TAATACATTA AGCGTTTGAG 8220 TCTAAGATGA AAGGAGAACA CTGGTTATGT TGATAGAATG ATAAAAAGGG TCGGGCGCGG 8280 AGGCTCACGC CTGTAATCCC AGCCCTTTGG GAGGCCGAGG TGGGCAGATC ACGAAGTCAG 8340 TAGTTTGAGA CCAGCCTGGC CAACATAGTG AAACCCCGTC TCTACTAAAA ATACAAAAAA 8400 AAAATTAGCT GGGTGTGGTG GCAGTCACCT GTAGTCCCAG CTACTTGGGA GGATGAGGCA 8460 GGAGAATCGC TTGAACCTGG GAGGCGGAGG TTGCAGTGAG CCGAGATCGC ACCAGTGCAC 8520 TCCAGCCTTG GTGACAATGG GAGACTCCAT CTCAAAAAAA AAAAAAAAAA AAAAAAGATA 8580 AAAAGTCAGA AATCTGAAAA GTGGAGGAAG AGTACAAATA GACCTAAATT AAGTCTCATT 8640 TTTTGGCTTT GATTTTGGGG AGACAAAGGG AAATGCAGCC ATAGAGGGCC TGATGACATC 8700 CAATACATGA GTTCTGGTAA AGATAAAATT TGATACACGG TTTGGTGTCA TTATAAGAGA 8760 AATCATTATT AAATGAAGCA AGTTAACACT CTAAGAGAAT TATTTTGAGA TAGAAGTGAA 8820 GCTAAGCTAA ACTTCACATG CCTATAATTG GAGGGAAAAA CTAAGGATAA AATCTAGCCT 8880 AGAAGATACA ATAATTAGTC ATAAACATGC ATTGTGAAAC TGTAGAGAGC AGGTAGCCCA 8940 AAATAGAGAA AGATTAGATA AAGAGAAAAT AAGTATCCAT CAGAGACAGT ATCTCTAGGC 9000 TTGGGCAAGA GAAAAGTCCA CAGTGATAAG CAACTCCACC TAAGGCATGA ATATGCGGCA 9060 GAGAAAACAG CAATAGTGAA TGAATGCAAA AGGTGCTGAG CAAATTCCAC ACATGAGTAT 9120 TGTGCATGAG TAAATGAATA AAACATTTGC AAAGACCTTT AGAGAAAGAG AATGGGAGCA 9180 TATGTGCGAA ATAAGATAGT TGATTATGAA TAGAAGGTAG TGAAGAAAAG CAAGCTAAGA 9240 AAAAATTCTG TTTATAAAAG AGGAAAAGA TAGTTTATGT TTTTAGCCTA AGTATAAGAG 9300 TCCTACAGAT GGACTGAAAA AAATCAGTCT GAGAGTATTA GTCACAATTA ATGAAATAAT 9360 TACATTTTAT GTATTGAGGA TGCCAAGATT AAAAGGTGAC AGGTAGATGT TAATTTCCCT 9420 AGATTGTGAA AGTGATCACG ACAATCACAC AACAAATAAT TAAGTGACTT GGTATGCTTT 9480 ATTTAATTGT AGGGCCTGAG GTTTTCCATT CTCATTTTTC TAAAATACAA TTTTGTTTCT 9540 CCAAATTTGA CAGCAGAATA AAAACCCTAC CCTTTCACTG TGTATCATGC TAAGCTGCAT 9600 CTCTACTCTT GATCATCTGT AGGTATTAAT CACATCACTT CCATGGCATG GATGTTCACA 9660 TACAGACTCT TAACCCTGGT TTACCAGGAC CTCTAGGAGT GGATCCAATC TATATCTTTA 9720 CAGTTGTATA GTATATGATA TCTCTTTTAT TTCACTCAAT TTATATTTTC ATCATTGACT 9780 ACATATTTCT TATACACAAC ACACAATTTA TGAATTTTTT CTCAAGATCA TTCTGAGAGT 9840 TGCCCCACCC TACCTGCCTT TTATAGTACG CCCACCTCAG GCAGACACAG AGCACAATGC 9900 TGGGGTTCTC TTCACACTAT CACTGCCCCA AATTGTCTTT CTAAATTTCA ACTTCAATGT 9960 CATCTTCTCC ATGAAGACCA CTGAATGAAC ACCTTTTCAT CCAGCCTTAA TTTCTTGCTC 10020 CATAACTACT CTATCCCACG ATGCAGTATT GTATCATTAA TTATTAGTGT GCTTGTGACC 10080 TCCTTATGTA TTCTCAATTA CCTGTATTTG TGCAATAAAT TGGAATAATG TAACTTGATT 10140 SUBSTITUTE SHEET ISA/EP TCTTATCTGT GTTTGTGTTG GCATGCAAGA TTTAGGTACT TATCAAGATA ATGGGGAATT 10200 AAGGCATCAA TAAAATGATG CCAAAGACCA AGAGCAGTTT CTGAAGTCCT CCTTTTCATC 10260 AGCTCTTTAT CAAACAGAAC ACTCTATAAA CAACCCATAG CCAGAAAACA GGATGTAGGA 10320 ACAATCACCA GCACACTCTA TAAACAACCC ATAGCCAGAA AACAGAATGT AAGGACAATC 10380 ACCAGCCATC TTTTGTCAAT AATTGATGGA ATAGAGTTGA AAGGAACTGG AGCATGAGTC 10440 ATATTTGACC AGTCAGTCCT CACTCTTATT TACTTGCTAT GTAAACTTGA GAAAGCTTTT 10500 TTCTCTTTGT GAACCTCAGG TTTTACATCT GAAAATGAGA AATTTGGAAC AAAAGATTCC 10560 TAACTGGTCT TTCTGTTCCC ATATTCTGTG ATTTTTCAAT ATTTAGGATT TTTGGTAATC 10620 ACAATTACTT AGTTTGTGGT TGAGATAGCA ACACGAATCA GAACTATTTG GTGGACATAT 10680 TTTCAAAGGA GTAGCTCTCC ACTTTGGGTA AAGAAGTGAT GCNGGTCGTG GTGGCTCACG 10740 CCTGTAATCC CAGCACTTTA GGGAGGCCAA GGCGGGTGGA TCACGAGGTC AGGAGATCGA 10800 GACCATCCTG GCTAACACGG TGAAACCCCG TCTCTACTAA AAAATACAAA AAATTAGCCA 10860 GGCGTGGTGG CGGGCGCCTG TAGTCCCACG TACTCGGGAG GCTGAGGCAG GAGAATGGCA 10920 TGAACCAGGG AGGCGGAGCT TGCCGTGAGC CGAGATAGCG CCACTGCAGT CCCTCCTGGG 10980 CAAAAGAGCA AGACTGCGTC TCAAAAAAAA AAAAAAAAAA AAAAAAAGAA GTGTGTGGAG 11040 TAGCAGGACA CCTGCAACAA TAATATTTTT CTAAATCCCT CTGAAAAATG CTAATCAAAG 11100 GGTTTTTTTC CTAAAAATTG TCTTAGAAAT AAAATTTCCC CTTTGGGAGA CCGAGGCTGG 11160 CAGATCACGA GGTCAGGAGA TAGAGACCAC GGTGAAACCC CGTCTCTACT AAAAATACTA 11220 AAAATTAGCC GGGGNGTGGT GGTGGGTACA CCTGTAGTCC CAGCTACTTG GAGGCTGAGG 11280 CTGGAGAATC ACGTGAAC 11298 (2) INFORMATION FOR SEQ ID NO:32: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 244 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: homo sapien (B) STRAIN: FcRI beta subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:32: Met Asp Thr Glu Ser Asn Arg Arg Ala Asn Leu Ala Leu Pro Gin Glu 1 5 10 15 Pro Ser Ser Val Pro Ala Phe Glu Val Leu Glu He Ser Pro Gin Glu 20 25 30 Val Ser Ser Glv Arg Leu Leu Lys Ser Ala Ser Ser Pro Pro Leu His 35 40 45 Thr Trp Leu Thr Val Leu Lys Lys Glu Gin Glu Phe Leu Gly Val Thr 50 55 60 SUBSTITUTE SHEET ISA/EP Gin He Leu Thr Ala Met He Cys Leu Cys Phe Gly Thr Val Val cys 65 70 75 80 Ser Val Leu Asp He Ser His He Glu Gly Asp He Phe Ser Ser Phe 85 90 95 Lys Ala Gly Tyr Pro Phe Trp Gly Ala He Phe Phe Ser He Ser Gly 100 105 110 Met Leu Ser He He Ser Glu Arg Arg Asn Ala Thr Tyr Leu Val Arg 115 120 125 Gly Ser Leu Gly Ala Asn Thr Ala Ser Ser He Ala Gly Gly Thr Gly 130 135 140 He Thr He Leu He He Asn Leu Lys Lys Ser Leu Ala Tyr He His 145 150 155 160 He His Ser Cys Gin Lys Phe Phe Glu Thr Lys Cys Phe Met Ala Ser 165 170 175 Phe Ser Thr Glu He Val Val Met Met Leu Phe Leu Thr He Leu Gly 180 185 190 Leu Gly Ser Ala Val Ser Leu Thr He Cys Gly Ala Gly Glu Glu Leu 195 200 205 Lys Gly Asn Lys Val Pro Glu Asp Arg Val Tyr Glu Glu Leu Asn He 210 215 220 Tyr Ser Ala Thr Tyr Ser Glu Leu Glu Asp Pro Gly Glu Met Ser Pro 225 230 235 240 Pro He Asp Leu (2) INFORMATION FOR SEQ ID NO:33: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 243 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: rat (B) STRAIN: FcRI beta subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:33: Met Asp Thr Glu Asn Lys Ser Arg Ala Asp Leu Ala Leu Pro Asn Pro 1 5 10 15 Gin Glu Ser Pro Ser Ala Pro Asp He Glu Leu Leu Glu Ala Ser Pro 20 25 30 Pro Ala Lys Ala Leu Pro Glu Lys Pro Ala Ser Pro Pro Pro Gin Gin 35 40 45 Thr Trp Gin Ser Phe Leu Lys Lys Glu Leu Glu Phe Leu Gly Val Thr 50 55 60 Gin Val Leu Val Gly Leu He Cys Leu Cys Phe Gly Thr Val Val Cys 65 70 75 80 SUBSTITUTE SHEET ISA/EP Ser Thr Leu Gin Thr Ser Asp Phe Asp Asp Glu Val Leu Leu Leu Tyr 85 90 95 Arg Ala Gly Tyr Pro Phe Trp Gly Ala Val Leu Phe Val Leu Ser Gly 100 105 110 Phe Leu Ser lie Met Ser Glu Arg Lys Asn Thr Leu Tyr Leu Val Arg 115 120 125 Gly Ser Leu Gly Ala Asn He Val Ser Ser He Ala Ala Gly Leu Gly 130 135 140 He Ala He Leu He Leu Asn Leu Ser Asn Asn Ser Ala Tyr Met Asn 145 150 155 160 Tyr Cys Lys Asp He Thr Glu Asp Asp Gly Cys Phe Val Thr Ser Phe 165 170 175 He Thr Glu Leu Val Leu Met Leu Leu Phe Leu Thr He Leu Ala Phe 180 185 190 Cys Ser Ala Val Leu Leu He He Tyr Arg He Gly Gin Glu Phe Glu 195 200 205 Arg Ser Lys Val Pro Asp Asp Arg Leu Tyr Glu Glu Leu His Val Tyr 210 215 220 Ser Pro He Tyr Ser Ala Leu Glu Asp Thr Arg Glu Ala Ser Ala Pro 225 230 235 240 Val Val Ser (2) INFORMATION FOR SEQ ID NO:34: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 235 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (vi) ORIGINAL SOURCE: (A) ORGANISM: mouse (B) STRAIN: FcRI. beta subunit (xi) SEQUENCE DESCRIPTION: SEQ ID NO:34: Met Asp Thr Glu Asn Arg Ser Arg Ala Asp Leu Ala Leu Pro Asn Pro 1 5 10 15 Gin Glu Ser Ser Ser Ala Pro Asp He Glu Leu Leu Glu Ala Ser Pro 20 25 30 Ala Lys Ala Ala Pro Pro Lys Gin Thr Trp Arg Thr Phe Leu Lys Lys 35 40 45 Glu Leu Glu Phe Leu Gly Ala Thr Gin He Leu Val Gly Leu He Cys 50 55 60 Leu Cys Phe Gly Thr He Val Cys Ser Val Leu Tyr Val Ser Asp Phe 65 70 75 80 Asp Glu Glu Val Leu Leu Leu Tyr Lys Leu Gly Tyr Pro Phe Trp Gly 85 90 95 SUBSTITUTE SHEET ISA/EP Ala Val Leu Phe Val Leu Ser Gly Phe Leu Ser He He Ser Glu Arg 100 105 110 Lys Asn Thr Leu Tyr Leu Val Arg Gly Ser Leu Gly Ala Asn He Val 115 120 125 Ser Ser He Ala Ala Gly Thr Gly He Ala Met Leu He Leu Asn Leu 130 135 140 Thr Asn Asn Phe Ala Tyr Met Asn Asn Cys Lys Asn Val Thr Glu Asp 145 150 155 160 Asp Gly Cys Phe Val Ala Ser Phe Thr Thr Glu Leu Val Leu Met Met 165 170 175 Leu Phe Leu Thr He Leu Ala Phe Cys Ser Ala Val Leu Phe Thr He 180 185 190 Tyr Arg He Gly Gin Glu Leu Glu Ser Lys Lys Val Pro Asp Asp Arg 195 200 205 Leu Tyr Glu Glu Leu Asn Val Tyr Ser Pro He Tyr Ser Glu Leu Glu 210 215 220 Asp Lys Gly Glu Thr Ser Ser Pro Val Asp Ser 225 230 235 SUBSTITUTE SHEET ISA/EP

Claims: WHAT IS CLAIMED IS: 1. A nucleic acid sequence capable of coding for a polypeptide having an amino acid sequence corresponding to the human beta subunit of Fc f RI. 2. The nucleic acid sequence of claim 1 further defined as a DNA sequence. 3. The DNA sequence according to claim 2, wherein said DNA sequence corresponds to that shown in FIG. 14 (SEQ ID NO:31) , or an allelic or species variation thereof. 4. The DNA sequence according to claim 2, wherein said DNA segment encodes the human amino acid sequence set forth in FIG. 19 (SEQ ID NO:32), or an allelic or species variation thereof. 5. A polypeptide having an amino acid sequence corresponding to the human beta subunit of Fc ^ RI, isolated from its natural environment. 6. The polypeptide according to claim 5, wherein said polypeptide has the hvunan amino acid sequence set forth in FIG. 19 (SEQ ID NO:32) , or an allelic or species variation thereof. 7. A recombinant DNA molecule comprising a vector and the DNA sequence according to claim 2 or 3. 8. A cell that contains the recombinant DNA molecule according to claim 7. 9. A method of producing a polypeptide having an amino acid sequence corresponding to the human beta subunit of Fc^I, said method comprising culturing the cell according to claim 8 under conditions such that said SUBSTITUTESHEET ISA/EP DNA molecule is expressed, and saiα polypeptide thereby produced. 10. The method of claim 9 further comprising isolating said polypeptide from the cell. 11. A method of expressing a complete and functional human Fc < RI receptor as characterized in mast cells comprising introducing into a host cell nucleic acid segments capable of encoding the human α, β, and y subunits of Fc t RI and effecting expression of said segments under conditions such that said receptor is formed. 12. The method of claim 11 wherein the nucleic acid segments are DNA segments. 13. A nucleic acid segment capable of hybridization with a segment of the mRNA from which the human beta subunit is translated and, when so hybridized, capable of inhibiting said translation. 14. An antibody capable of binding to the beta subunit polypeptide of claim 5 or the amino acid sequence of claim 4 and neutralizing the Fc,RI-related functions of the subunit. 15. The antibody of claim 14 which is a monoclonal antibody. 16. A nucleic acid segment comprising a hybridizing segment of at least approximately 14 nucleotides which is capable of hybridizing to a nucleic acid segment capable of encoding for at least an amino acid sequence comprising the aggregating functions of a human beta subunit under stringent conditions. SUBSTITUTE SHEET ISA/EP 17. An amino acid sequence capable of binding ro the amino acid sequence of the human beta subunit and inhibiting the aggregating functions of the subunit. 18. The nucleic acid segment of claim 16 further defined as capable of hybridizing to a mRNA capable of transcribing at least a fragment of the β subunit. 19. A recombinant expression vector which comprises a nucleic acid sequence encoding the human β subunit and from which said subunit is capable of being expressed when the vector is in a host cell. 20. A recombinant expression vector comprising a nucleic acid sequence selected from one of the following claims: l, 13, 16, and 29. 21. A cell transfected with the nucleic acid segments of claims l, 13, 16, or 29. 22. The transfected cell of claim 21 wherein the cell prior to transfection was selected from the group comprising CHO, COS, KU812, P815, Jurkett, 2M2 and 2B4 cells. 23. A method for determining the ability of a candidate substance to inhibit the formation or function of the human FC j I, comprising: (a) conferring on a host cell the ability to express the a, β, and y subunits of the human Fc £ RI; (b) combining the host cell after step (a) with the candidate inhibitor substance; (c) placing the combination in conditions suitable for expression of Fc c RI; SUBSTITUTE SHEET (d) performing on the host cell candidate inhibitor combination of step c an assay for cell expression or for cell activation of a type which requires a functional human Fc,RI; and (e) determining whether the candidate substance has inhibited cell activation or receptor expression. 24. The method of claim 23 wherein the host cell is selected from the group consisting of CHO cells, T cells, KU818 and P815 cells, and the cell activation assay comprises measuring the phosphorylation of the Fc t RI receptor or of PLC~7(phospholipase c-7) by P 32 label uptake. 25. The method of claim 23 wherein the host cell is selected from the group consisting of T cells, KU812 cells and P815 cells, and the cell activation assay comprises measuring calcium uptake response. 26. The method of claim 23 wherein the host cell is selected from the group consisting of T cells, KU812 cells and P815 cells, and the cell activation assay is the phosphatydil inositol metabolism. 27. A composition for the treatment of allergic diseases comprising human beta subunit inhibitor in a pharmaceutically acceptable carrier. 28. A method of treatment of allergic diseases in a human suffering therefrom, such method comprising administering to said human an amount of human beta subunit inhibitor effective to indirectly inhibit the binding of IgE to Fc € RI and to inhibit the aggregation function of the receptor or the signal transducing function related to allergic response. SUBSTITUTE SHEET 29. A nucleic acid sequence coding ior the amino acid sequence of claim 17. SUBSTITUTESHEET ISA/EP

Inventors: KINET JEAN PIERRE, KINET, JEAN, PIERRE
Applicants: US HEALTH, THE UNITED STATES OF AMERICA, AS REPRESENTED BY TH
Application year: 1993
Main classification: C12N15
IPC codes: A61K38, A61K39, A61P37, C07H21, C07K14, C07K16, C12N1, C12N5, C12N15, C12P21, C12Q1, C12R1