ID   CD79A_BOVIN             Reviewed;         223 AA.
AC   P40293; Q0P5B8; Q28134;
DT   01-FEB-1995, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1995, sequence version 1.
DT   24-JAN-2024, entry version 157.
DE   RecName: Full=B-cell antigen receptor complex-associated protein alpha chain;
DE   AltName: Full=Ig-alpha;
DE   AltName: Full=MB-1 membrane glycoprotein;
DE   AltName: Full=Membrane-bound immunoglobulin-associated protein;
DE   AltName: Full=Surface IgM-associated protein;
DE   AltName: CD_antigen=CD79a;
DE   Flags: Precursor;
GN   Name=CD79A; Synonyms=IGA, MB-1;
OS   Bos taurus (Bovine).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Artiodactyla; Ruminantia; Pecora; Bovidae;
OC   Bovinae; Bos.
OX   NCBI_TaxID=9913;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA] (ISOFORMS 1 AND 2).
RC   TISSUE=Leukocyte, and Lymphoblast;
RX   PubMed=7963570;
RA   Youn H.-Y., Goitsuka R., Okuda M., Watari T., Tsujimoto H., Hasegawa A.;
RT   "Two forms of the mb-1 gene transcript in cattle.";
RL   J. Immunol. 153:5127-5132(1994).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
RX   PubMed=8810000; DOI=10.1016/0165-2427(95)05546-0;
RA   Youn H.-Y., Goitsuka R., Kato H., Mason D.Y., Watari T., Tsujimoto H.,
RA   Hasegawa A.;
RT   "Molecular cloning of bovine mb-1 cDNA.";
RL   Vet. Immunol. Immunopathol. 52:191-200(1996).
RN   [3]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
RC   STRAIN=Hereford; TISSUE=Thymus;
RG   NIH - Mammalian Gene Collection (MGC) project;
RL   Submitted (AUG-2006) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Required in cooperation with CD79B for initiation of the
CC       signal transduction cascade activated by binding of antigen to the B-
CC       cell antigen receptor complex (BCR) which leads to internalization of
CC       the complex, trafficking to late endosomes and antigen presentation.
CC       Also required for BCR surface expression and for efficient
CC       differentiation of pro- and pre-B-cells. Stimulates SYK
CC       autophosphorylation and activation. Binds to BLNK, bringing BLNK into
CC       proximity with SYK and allowing SYK to phosphorylate BLNK. Also
CC       interacts with and increases activity of some Src-family tyrosine
CC       kinases. Represses BCR signaling during development of immature B-cells
CC       (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Heterodimer of alpha and beta chains; disulfide-linked. Part
CC       of the B-cell antigen receptor complex where the alpha/beta chain
CC       heterodimer is non-covalently associated with an antigen-specific
CC       membrane-bound surface immunoglobulin of two heavy chains and two light
CC       chains. Interacts through its phosphorylated ITAM domain with the SH2
CC       domains of SYK which stimulates SYK autophosphorylation and activation.
CC       Also interacts, when phosphorylated on Tyr-207, with the SH2 domain of
CC       BLNK/SLP65, bringing BLNK into proximity with SYK and allowing SYK to
CC       phosphorylate BLNK which is necessary for trafficking of the BCR to
CC       late endosomes. Interacts with Src-family tyrosine kinases including
CC       FYN and LYN, increasing their activity (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cell membrane; Single-pass type I membrane
CC       protein. Note=Following antigen binding, the BCR has been shown to
CC       translocate from detergent-soluble regions of the cell membrane to
CC       lipid rafts although signal transduction through the complex can also
CC       occur outside lipid rafts. {ECO:0000250}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative splicing; Named isoforms=2;
CC       Name=1;
CC         IsoId=P40293-1; Sequence=Displayed;
CC       Name=2;
CC         IsoId=P40293-2; Sequence=VSP_027221, VSP_027222;
CC   -!- TISSUE SPECIFICITY: B-cells.
CC   -!- DOMAIN: The transmembrane helices of CD79A and CD79B chains and two IgM
CC       heavy chains assembly in a four-helix bundle structure that appears to
CC       be conserved among different BCR isotypes.
CC       {ECO:0000250|UniProtKB:P11912}.
CC   -!- PTM: Phosphorylated on tyrosine, serine and threonine residues upon B-
CC       cell activation. Phosphorylation of tyrosine residues by Src-family
CC       kinases, including LYN, is an early and essential feature of the BCR
CC       signaling cascade. The phosphorylated tyrosines serve as docking sites
CC       for SH2-domain containing kinases, leading to their activation which in
CC       turn leads to phosphorylation of downstream targets. Phosphorylation of
CC       serine and threonine residues may prevent subsequent tyrosine
CC       phosphorylation (By similarity). {ECO:0000250}.
CC   -!- PTM: Arginine methylation in the ITAM domain may interfere with the
CC       binding of SYK. It promotes signals leading to B-cell differentiation
CC       (By similarity). {ECO:0000250}.
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DR   EMBL; D16412; BAA03899.1; -; mRNA.
DR   EMBL; D16459; BAA03926.1; -; mRNA.
DR   EMBL; BC120260; AAI20261.1; -; mRNA.
DR   PIR; I45927; I45927.
DR   RefSeq; NP_776691.2; NM_174266.4. [P40293-1]
DR   AlphaFoldDB; P40293; -.
DR   SMR; P40293; -.
DR   STRING; 9913.ENSBTAP00000002451; -.
DR   GlyCosmos; P40293; 4 sites, No reported glycans.
DR   PaxDb; 9913-ENSBTAP00000002451; -.
DR   Ensembl; ENSBTAT00000002451.4; ENSBTAP00000002451.3; ENSBTAG00000001882.5. [P40293-1]
DR   GeneID; 281674; -.
DR   KEGG; bta:281674; -.
DR   CTD; 973; -.
DR   VEuPathDB; HostDB:ENSBTAG00000001882; -.
DR   eggNOG; ENOG502S1DI; Eukaryota.
DR   GeneTree; ENSGT00940000154363; -.
DR   HOGENOM; CLU_106774_0_0_1; -.
DR   InParanoid; P40293; -.
DR   OMA; RWQNEKF; -.
DR   OrthoDB; 5361630at2759; -.
DR   TreeFam; TF336032; -.
DR   Reactome; R-BTA-5690714; CD22 mediated BCR regulation.
DR   Reactome; R-BTA-983695; Antigen activates B Cell Receptor (BCR) leading to generation of second messengers.
DR   Proteomes; UP000009136; Chromosome 18.
DR   Bgee; ENSBTAG00000001882; Expressed in blood and 83 other cell types or tissues.
DR   ExpressionAtlas; P40293; baseline and differential.
DR   GO; GO:0019815; C:B cell receptor complex; ISS:UniProtKB.
DR   GO; GO:0009897; C:external side of plasma membrane; ISS:UniProtKB.
DR   GO; GO:0071755; C:IgM B cell receptor complex; ISS:UniProtKB.
DR   GO; GO:0045121; C:membrane raft; ISS:UniProtKB.
DR   GO; GO:0005771; C:multivesicular body; ISS:UniProtKB.
DR   GO; GO:0042802; F:identical protein binding; IEA:Ensembl.
DR   GO; GO:0004888; F:transmembrane signaling receptor activity; IEA:Ensembl.
DR   GO; GO:0002250; P:adaptive immune response; IEA:UniProtKB-KW.
DR   GO; GO:0042113; P:B cell activation; ISS:UniProtKB.
DR   GO; GO:0030183; P:B cell differentiation; ISS:UniProtKB.
DR   GO; GO:0042100; P:B cell proliferation; ISS:UniProtKB.
DR   GO; GO:0050853; P:B cell receptor signaling pathway; ISS:UniProtKB.
DR   CDD; cd00096; Ig; 1.
DR   Gene3D; 2.60.40.10; Immunoglobulins; 1.
DR   InterPro; IPR039695; CD79a/CD79b.
DR   InterPro; IPR007110; Ig-like_dom.
DR   InterPro; IPR036179; Ig-like_dom_sf.
DR   InterPro; IPR013783; Ig-like_fold.
DR   InterPro; IPR003599; Ig_sub.
DR   InterPro; IPR003598; Ig_sub2.
DR   InterPro; IPR003110; Phos_immunorcpt_sig_ITAM.
DR   PANTHER; PTHR14334; B-CELL ANTIGEN RECEPTOR COMPLEX-ASSOCIATED PROTEIN; 1.
DR   PANTHER; PTHR14334:SF1; B-CELL ANTIGEN RECEPTOR COMPLEX-ASSOCIATED PROTEIN ALPHA CHAIN; 1.
DR   Pfam; PF13927; Ig_3; 1.
DR   Pfam; PF02189; ITAM; 1.
DR   SMART; SM00409; IG; 1.
DR   SMART; SM00408; IGc2; 1.
DR   SMART; SM00077; ITAM; 1.
DR   SUPFAM; SSF48726; Immunoglobulin; 1.
DR   PROSITE; PS50835; IG_LIKE; 1.
DR   PROSITE; PS51055; ITAM_1; 1.
PE   2: Evidence at transcript level;
KW   Adaptive immunity; Alternative splicing; Cell membrane; Disulfide bond;
KW   Glycoprotein; Immunity; Immunoglobulin domain; Membrane; Methylation;
KW   Phosphoprotein; Reference proteome; Signal; Transmembrane;
KW   Transmembrane helix.
FT   SIGNAL          1..31
FT                   /evidence="ECO:0000255"
FT   CHAIN           32..223
FT                   /note="B-cell antigen receptor complex-associated protein
FT                   alpha chain"
FT                   /id="PRO_0000014557"
FT   TOPO_DOM        32..140
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        141..161
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        162..223
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   DOMAIN          32..120
FT                   /note="Ig-like C2-type"
FT   DOMAIN          174..202
FT                   /note="ITAM"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00379"
FT   SITE            207
FT                   /note="Required for binding to BLNK"
FT                   /evidence="ECO:0000250"
FT   MOD_RES         185
FT                   /note="Phosphotyrosine; by SRC-type Tyr-kinases"
FT                   /evidence="ECO:0000250|UniProtKB:P11911,
FT                   ECO:0000255|PROSITE-ProRule:PRU00379"
FT   MOD_RES         196
FT                   /note="Phosphotyrosine"
FT                   /evidence="ECO:0000250|UniProtKB:P11911,
FT                   ECO:0000255|PROSITE-ProRule:PRU00379"
FT   MOD_RES         201
FT                   /note="Asymmetric dimethylarginine; by PRMT1"
FT                   /evidence="ECO:0000250|UniProtKB:P11911"
FT   MOD_RES         207
FT                   /note="Phosphotyrosine; by Tyr-kinases"
FT                   /evidence="ECO:0000250|UniProtKB:P11911,
FT                   ECO:0000255|PROSITE-ProRule:PRU00379"
FT   CARBOHYD        56
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        61
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        71
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        95
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        53..104
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
FT   DISULFID        116
FT                   /note="Interchain (with beta chain)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
FT   VAR_SEQ         124..133
FT                   /note="DPLPRPFLDM -> ETMAEHEIRG (in isoform 2)"
FT                   /evidence="ECO:0000303|PubMed:7963570"
FT                   /id="VSP_027221"
FT   VAR_SEQ         134..223
FT                   /note="Missing (in isoform 2)"
FT                   /evidence="ECO:0000303|PubMed:7963570"
FT                   /id="VSP_027222"
SQ   SEQUENCE   223 AA;  24630 MW;  CE2F0AF175748304 CRC64;
     MPEGPQALQS PPATIFLLLI SAAGLGPGCQ ALWVEWGPPS VTVSVGEEVR LQCTHNGSNT
     NVTWWHVLQS NSSWPPVMYR GDVGAGGELI IKPVNKTHRG MYRCQVSDGK KIQRSCGTYL
     RVRDPLPRPF LDMGEGTKNN IITAEGIILL ICAVVPGTLL LFRKRWQNMK FGADIQDDYE
     DENLYEGLNL DDCSMYEDIS RGLQGTYQDV GSLHIGDAQL EKP
//