ID   CD8B_PONPY              Reviewed;         210 AA.
AC   P30434;
DT   01-APR-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1993, sequence version 1.
DT   25-MAY-2022, entry version 114.
DE   RecName: Full=T-cell surface glycoprotein CD8 beta chain;
DE   AltName: CD_antigen=CD8b;
DE   Flags: Precursor;
GN   Name=CD8B; Synonyms=CD8B1;
OS   Pongo pygmaeus (Bornean orangutan).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae;
OC   Pongo.
OX   NCBI_TaxID=9600;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=Isolate Jari;
RX   PubMed=1612644; DOI=10.1007/bf00215289;
RA   Lawlor D.A., Parham P.;
RT   "Structure of CD8 alpha and beta chains of the orangutan: novel patterns of
RT   mRNA splicing encoding hingeless polypeptides.";
RL   Immunogenetics 36:121-125(1992).
CC   -!- FUNCTION: Integral membrane glycoprotein that plays an essential role
CC       in the immune response and serves multiple functions in responses
CC       against both external and internal offenses. In T-cells, functions
CC       primarily as a coreceptor for MHC class I molecule:peptide complex. The
CC       antigens presented by class I peptides are derived from cytosolic
CC       proteins while class II derived from extracellular proteins. Interacts
CC       simultaneously with the T-cell receptor (TCR) and the MHC class I
CC       proteins presented by antigen presenting cells (APCs). In turn,
CC       recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. A
CC       palmitoylation site in the cytoplasmic tail of CD8B chain contributes
CC       to partitioning of CD8 into the plasma membrane lipid rafts where
CC       signaling proteins are enriched. Once LCK recruited, it initiates
CC       different intracellular signaling pathways by phosphorylating various
CC       substrates ultimately leading to lymphokine production, motility,
CC       adhesion and activation of cytotoxic T-lymphocytes (CTLs).
CC       Additionally, plays a critical role in thymic selection of CD8+ T-
CC       cells. {ECO:0000250|UniProtKB:P10300, ECO:0000250|UniProtKB:P10966}.
CC   -!- SUBUNIT: Forms disulfide-linked heterodimers with CD8A at the cell
CC       surface. Interacts with CD3D; this interaction couples TCR-CD3 with
CC       CD8. Interacts with LCK. {ECO:0000250|UniProtKB:P10300,
CC       ECO:0000250|UniProtKB:P10966}.
CC   -!- SUBCELLULAR LOCATION: Cell membrane {ECO:0000250|UniProtKB:P10966};
CC       Single-pass type I membrane protein {ECO:0000250|UniProtKB:P10966}.
CC       Note=Requires the partner CD8A for efficient cell surface expression.
CC       The heterodimer CD8A/CD8B localizes to lipid rafts due to CD8B
CC       cytoplasmic tail palmitoylation. {ECO:0000250|UniProtKB:P10966}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative splicing; Named isoforms=1;
CC         Comment=A number of isoforms are produced. Alternative splicing
CC         involves excision of the hinge or cytoplasmic domains.;
CC       Name=1;
CC         IsoId=P30434-1; Sequence=Displayed;
CC   -!- PTM: Phosphorylated as a consequence of T-cell activation.
CC       {ECO:0000250|UniProtKB:P10966}.
CC   -!- PTM: Palmitoylated at the cytoplasmic tail and thereby targets the
CC       heterodimer CD8A/CD8B to lipid rafts unlike CD8A homodimers.
CC       {ECO:0000250|UniProtKB:P10966}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; X60222; CAA42783.1; -; mRNA.
DR   PIR; S25657; S25657.
DR   AlphaFoldDB; P30434; -.
DR   SMR; P30434; -.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0005886; C:plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0015026; F:coreceptor activity; IEA:InterPro.
DR   GO; GO:0042288; F:MHC class I protein binding; IEA:InterPro.
DR   GO; GO:0002250; P:adaptive immune response; IEA:UniProtKB-KW.
DR   GO; GO:0050776; P:regulation of immune response; IEA:InterPro.
DR   Gene3D; 2.60.40.10; -; 1.
DR   InterPro; IPR042414; CD8B.
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; IPR013106; Ig_V-set.
DR   PANTHER; PTHR11292; PTHR11292; 1.
DR   Pfam; PF07686; V-set; 1.
DR   SMART; SM00409; IG; 1.
DR   SMART; SM00406; IGv; 1.
DR   SUPFAM; SSF48726; SSF48726; 1.
DR   PROSITE; PS50835; IG_LIKE; 1.
PE   2: Evidence at transcript level;
KW   Adaptive immunity; Alternative splicing; Cell membrane; Disulfide bond;
KW   Glycoprotein; Immunity; Immunoglobulin domain; Lipoprotein; Membrane;
KW   Palmitate; Signal; Transmembrane; Transmembrane helix.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000250"
FT   CHAIN           22..210
FT                   /note="T-cell surface glycoprotein CD8 beta chain"
FT                   /id="PRO_0000014645"
FT   TOPO_DOM        22..170
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        171..191
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        192..210
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   DOMAIN          22..132
FT                   /note="Ig-like V-type"
FT   CARBOHYD        102
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        41..116
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
SQ   SEQUENCE   210 AA;  23693 MW;  F455B0F281C73DC1 CRC64;
     MRPRLWLLLA AQLAVLHGSS VLQQTPAYIK VQTNKMVMLS CEAKISLSNM RIYWLRQRQA
     PSSDSHHEFL ALWDSAKGTI HSEEVEQEKV AVFRDASRFI LNLTSVKPED SGIYFCMIVG
     SPELTFGKGT QLSVVDFLPT TAQPTKKSTP KRRVCRLPRP ETQKGPLCSP ITLGLLVAGV
     LVLLVSLGVA IHLCCRRRRA RLRFMKQFYK