MHC Class I Polypeptide Related Sequence B (MICB)

MICB encodes a heavily glycosylated protein which is a ligand for the NKG2D type II receptor. Binding of the ligand activates the cytolytic response of natural killer (NK) cells, CD8 alphabeta T cells, and gammadelta T cells which express the receptor. This protein is stress-induced and is similar to MHC class I molecules; however, it does not associate with beta-2-microglobulin or bind peptides. MICB is a stress-induced ligand of the NK cell-activating receptor NKG2D and is critical for the NK cell killing of virus-infected cells and tumor cells.With intestinal epithelial cell lines, expression and recognition of MICA and MICB could be stress induced; thus, these molecules may broadly regulate protective responses by the V-delta-1 gamma/delta T cells in the epithelium of the intestinal tract.