FEATURES

DESCRIPTION

Also known as CD8A_HUMAN, CD8A, MAL. 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. 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. One HLA-A molecule (mainly via nonpolymorphic alpha-3 domain) interacts with one CD8A homodimer (via CDR-like loop) (PubMed:2784196, PubMed:9177355). Interacts with LCK in a zinc-dependent manner. Interacts with HLA-G; this interaction is direct and might down-regulate T cell receptor signaling.

EXTERNAL LINKS

CD8A

T-cell surface glycoprotein CD8 alpha chain

CD8A

Molecular Synopsis