MICB

Function

Widely expressed membrane-bound protein which acts as a ligand to stimulate an activating receptor KLRK1/NKG2D, expressed on the surface of essentially all human natural killer (NK), gammadelta T and CD8+ alphabeta T-cells (PubMed:11491531, PubMed:11777960). Up-regulated in stressed conditions, such as viral and bacterial infections or DNA damage response, serves as signal of cellular stress, and engagement of KLRK1/NKG2D by MICA triggers NK-cells resulting in a range of immune effector functions, such as cytotoxicity and cytokine production.

Involvement in disease

Rheumatoid arthritis

RA

An inflammatory disease with autoimmune features and a complex genetic component. It primarily affects the joints and is characterized by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures.

None

Disease susceptibility is associated with variants affecting the gene represented in this entry. The MICB*004 allele is associated with rheumatoid arthritis.

Genetic variation in MICB is associated with cytomegalovirus and herpes simplex virus I seropositivity and this may be associated with schizophrenia risk.

Post-translational modifications

Proteolytically cleaved and released from the cell surface of tumor cells.

Sequence Similarities

Belongs to the MHC class I family. MIC subfamily.

Tissue Specificity

Widely expressed with the exception of the central nervous system where it is absent. Expressed in many, but not all, epithelial tumors of lung, breast, kidney, ovary, prostate and colon. In hepatocellular carcinomas, expressed in tumor cells but not in surrounding non-cancerous tissue.

Cellular localization

• Cell membrane
• Single-pass type I membrane protein
• Binding to human cytomegalovirus glycoprotein UL16 causes sequestration in the endoplasmic reticulum.

Alternative names

PERB11.2, MICB, MHC class I polypeptide-related sequence B, MIC-B

Database links

swissprot:Q29980 omim:600169 omim:602436 swissprot:Q29983 entrezGene:4277 entrezGene:100507436