Recombinant Human MHC class I polypeptide-related sequence B (MICB), partial (Active)

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

Subcellular Location

Cell membrane (Single-pass type I membrane protein)

Disease Association

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. [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]

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

Subunit

(Microbial infection) Interacts with human cytomegalovirus/HHV-5 glycoprotein UL16; this interaction causes sequestration of MICB in the endoplasmic reticulum and increases resistance to KLRK1-mediated cytotoxicity

• Bahram S. et al. Nucleotide sequence of a human MHC class I MICB cDNA. — Immunogenetics (1996)
• Bahram S. et al. Genomic structure of the human MHC class I MICB gene. — Immunogenetics (1996)
• Martinez-Borra J. et al. The allele MICB*0050204, over-represented in the Caucasian population, has an additional exon resulting from a new splice junction sequence. — Hum. Immunol. (2007)
• Ota T. et al. Complete sequencing and characterization of 21,243 full-length human cDNAs. — Nat. Genet. (2004)
• Hirakawa M. et al. Homo sapiens 2,229,817bp genomic DNA of 6p21.3 HLA class I region. (DEC-)
• Mungall A.J. et al. The DNA sequence and analysis of human chromosome 6. — Nature (2003)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Gaudieri S. et al. Allelic and interlocus comparison of the PERB11 multigene family in the MHC. — Immunogenetics (1997)