UniProt functional annotation for P01731



	UniProt functional annotation for P01731

UniProt code: P01731.

Organism: Mus musculus (Mouse).

Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Glires; Rodentia; Myomorpha; Muroidea; Muridae; Murinae; Mus; Mus.

Function: Integral membrane glycoprotein that plays an essential role in the immune response and serves multiple functions in responses against both external and internal offenses. In T-cells, functions primarily as a coreceptor for MHC class I molecule:peptide complex. The antigens presented by class I peptides are derived from cytosolic proteins while class II derived from extracellular proteins. Interacts simultaneously with the T-cell receptor (TCR) and the MHC class I proteins presented by antigen presenting cells (APCs). In turn, recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. LCK then initiates different intracellular signaling pathways by phosphorylating various substrates ultimately leading to lymphokine production, motility, adhesion and activation of cytotoxic T- lymphocytes (CTLs). This mechanism enables CTLs to recognize and eliminate infected cells and tumor cells. In NK-cells, the presence of CD8A homodimers at the cell surface provides a survival mechanism allowing conjugation and lysis of multiple target cells. CD8A homodimer molecules also promote the survival and differentiation of activated lymphocytes into memory CD8 T-cells. {ECO:0000250|UniProtKB:P01732, ECO:0000269|PubMed:15105501, ECO:0000269|PubMed:1673361}.

Subunit: Forms disulfide-linked heterodimers with CD8B at the cell surface. Forms also homodimers in several cell types including NK-cells or peripheral blood T-lymphocytes. Interacts with the MHC class I HLA- A/B2M dimer. Interacts with LCK in a zinc-dependent manner. {ECO:0000250|UniProtKB:P01732, ECO:0000269|PubMed:18929574, ECO:0000269|PubMed:9806638}.

Subcellular location: Cell membrane {ECO:0000250|UniProtKB:P01732}; Single-pass type I membrane protein {ECO:0000250|UniProtKB:P01732}. Note=Cd8a localizes to lipid rafts only when associated with its partner Cd8b. {ECO:0000250|UniProtKB:P01732}.

Ptm: Palmitoylated, but association with CD8B seems to be more important for the enrichment of CdD8A in lipid rafts. {ECO:0000250|UniProtKB:P01732}.

Ptm: Phosphorylated in cytotoxic T-lymphocytes (CTLs) following activation. {ECO:0000269|PubMed:2512251}.

Disruption phenotype: Cd8a-deficient mice prevent the development of class I MHC restricted cytotoxic T-cells. However, maturation of class II MHC restricted T-helper cells seems to be unaffected by the absence of Cd8a. {ECO:0000269|PubMed:1673361}.

Annotations taken from UniProtKB at the EBI.


Organism:		Mus musculus (Mouse).
Taxonomy:		Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Glires; Rodentia; Myomorpha; Muroidea; Muridae; Murinae; Mus; Mus.



Function:		Integral membrane glycoprotein that plays an essential role in the immune response and serves multiple functions in responses against both external and internal offenses. In T-cells, functions primarily as a coreceptor for MHC class I molecule:peptide complex. The antigens presented by class I peptides are derived from cytosolic proteins while class II derived from extracellular proteins. Interacts simultaneously with the T-cell receptor (TCR) and the MHC class I proteins presented by antigen presenting cells (APCs). In turn, recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. LCK then initiates different intracellular signaling pathways by phosphorylating various substrates ultimately leading to lymphokine production, motility, adhesion and activation of cytotoxic T- lymphocytes (CTLs). This mechanism enables CTLs to recognize and eliminate infected cells and tumor cells. In NK-cells, the presence of CD8A homodimers at the cell surface provides a survival mechanism allowing conjugation and lysis of multiple target cells. CD8A homodimer molecules also promote the survival and differentiation of activated lymphocytes into memory CD8 T-cells. {ECO:0000250\|UniProtKB:P01732, ECO:0000269\|PubMed:15105501, ECO:0000269\|PubMed:1673361}.


Subunit:		Forms disulfide-linked heterodimers with CD8B at the cell surface. Forms also homodimers in several cell types including NK-cells or peripheral blood T-lymphocytes. Interacts with the MHC class I HLA- A/B2M dimer. Interacts with LCK in a zinc-dependent manner. {ECO:0000250\|UniProtKB:P01732, ECO:0000269\|PubMed:18929574, ECO:0000269\|PubMed:9806638}.
Subcellular location:		Cell membrane {ECO:0000250\|UniProtKB:P01732}; Single-pass type I membrane protein {ECO:0000250\|UniProtKB:P01732}. Note=Cd8a localizes to lipid rafts only when associated with its partner Cd8b. {ECO:0000250\|UniProtKB:P01732}.
Ptm:		Palmitoylated, but association with CD8B seems to be more important for the enrichment of CdD8A in lipid rafts. {ECO:0000250\|UniProtKB:P01732}.
Ptm:		Phosphorylated in cytotoxic T-lymphocytes (CTLs) following activation. {ECO:0000269\|PubMed:2512251}.
Disruption phenotype:		Cd8a-deficient mice prevent the development of class I MHC restricted cytotoxic T-cells. However, maturation of class II MHC restricted T-helper cells seems to be unaffected by the absence of Cd8a. {ECO:0000269\|PubMed:1673361}.