CD8A

CD8A (CD8a Molecule) is a Protein Coding gene. Diseases associated with CD8A include Cd8 Deficiency, Familial and Primary Cutaneous Aggressive Epidermotropic Cd8+ T-Cell Lymphoma. Among its related pathways are Hematopoietic Stem Cell Differentiation Pathways and Lineage-specific Markers and T-Cell Receptor and Co-stimulatory Signaling. Gene Ontology (GO) annotations related to this gene include protein homodimerization activity and coreceptor activity.

Full Name

CD8a Molecule

Alternative Names

CD8a Molecule; T-Lymphocyte Differentiation Antigen T8/Leu-2; T-Cell Surface Glycoprotein CD8 Alpha Chain; CD8 Antigen, Alpha Polypeptide (P32); MAL; Leu2 T-Lymphocyte Antigen; OKT8 T-Cell Antigen; T-Cell Antigen Leu2;

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.

Biological Process

Antigen processing and presentation Source: UniProtKB
Cell surface receptor signaling pathway Source: GO_Central
Cytotoxic T cell differentiation Source: GO_Central
Immune response Source: UniProtKB
Regulation of immune response Source: Reactome
T cell activation Source: UniProtKB
T cell mediated immunity Source: GO_Central
Transmembrane receptor protein tyrosine kinase signaling pathway Source: UniProtKB

Cellular Location

Isoform 1: Cell membrane. CD8A localizes to lipid rafts only when associated with its partner CD8B.
Isoform 2: Secreted

Involvement in disease

CD8 deficiency, familial (CD8 deficiency): An immunologic defect characterized by absence of CD8+ cells, leading to recurrent bacterial infections.

Topology

Extracellular: 22-182
Helical: 183-203
Cytoplasmic: 204-235

PTM

Palmitoylated, but association with CD8B seems to be more important for the enrichment of CD8A in lipid rafts.
O-glycosylated.
Phosphorylated in cytotoxic T-lymphocytes (CTLs) following activation.