protein_function: Seems to have no role in antigen presentation. Acts as astress-induced self-antigen that is recognized by gamma delta T-cells. Ligand for the KLRK1,NKG2D receptor. Binding to KLRK1 leadsto cell lysis..
MHC class I polypeptide-related sequence A is a protein that in humans is encoded by the MICA gene.1 The MICA gene encodes a 383-amino acid polypeptide with a predicted mass of 43 kD.The MICA and MICB genes occur in a 200-kb region spanning the TNFA and TNFB cluster at 6p21.3.2 MICA and the closely related MICB were recognized by intestinal epithelial T cells expressing diverse V-delta-1 gamma,delta TCRs.3 The MICA protein product is expressed on the cell surface, although unlike canonical class I molecules does not seem to associate with beta-2-microglobulin. It is further distinguished by its unusual exon-intron organization and preferential expression in fibroblasts and epithelial cells. It is thought that MICA functions as a stress-induced antigen that is broadly recognized by NK cells, NKT cells, and most of the subtypes of T cells. MICA and other members of this family may have been selected for specialized functions that are either ancient or derived from those of typical MHC class I genes, in analogy to some of the nonclassic mouse H-2 genes.
