MHC class I chain-related gene B Active Protein | MICB active protein
Recombinant Human MHC class I chain-related gene B
Sterile Filtered White lyophilized (freeze-dried) powder.
Introduction: MICB (MHC class I chain-related gene B) is a transmembrane glycoprotein that functions as a ligand for human NKG2D type II receptor. A closely related protein, MICA, shares 85% amino acid identity with MICB. These 2 proteins are distantly related to the MHC class I proteins. MICA and MICB (MICA/B) possess three extracellular immunoglobulin-like domains, but have no capacity to bind peptide or interact with ?2-microglobulin. The genes encoding MICA/B are found within the major histocompatibility complex on human chromosome 6. The MICB locus is polymorphic with more than 15 recognized human alleles. MICA/B are minimally expressed on normal cells, but are frequently expressed on epithelial tumors and can be induced by bacterial and viral infections. MICA/B are ligands for NKG2D, an activating receptor expressed on NK cells, NKT cells, T cells, and CD8+ T cells. Recognition of MICA/B by NKG2D results in the activation of cytolytic activity and/or cytokine production by these effector cells. MICA/B recognition is involved in tumor surveillance, viral infections, and autoimmune diseases. The release of soluble forms of MICA/B from tumors down-regulates NKG2D surface expression on effector cells resulting in the impairment of anti-tumor immune response.
NCBI and Uniprot Product Information
NCBI Description
This gene 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. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]
Uniprot Description
MICB: Seems to have no role in antigen presentation. Acts as a stress-induced self-antigen that is recognized by gamma delta T cells. Ligand for the KLRK1/NKG2D receptor. Binding to KLRK1 leads to cell lysis. Genetic variations in MICA are a cause of susceptibility to rheumatoid arthritis (RA). It is a systemic 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. 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. Belongs to the MHC class I family. MIC subfamily. 3 isoforms of the human protein are produced by alternative splicing.
Protein type: Membrane protein, integral
Chromosomal Location of Human Ortholog: 6p21.3
Cellular Component: cell surface; integral to membrane; plasma membrane
Molecular Function: beta-2-microglobulin binding; antigen binding; natural killer cell lectin-like receptor binding
Biological Process: antigen processing and presentation; regulation of immune response; response to retinoic acid; viral reproduction; response to heat; natural killer cell mediated cytotoxicity; cytolysis; immune response-activating cell surface receptor signaling pathway; negative regulation of defense response to virus by host; response to oxidative stress; gamma-delta T cell activation; T cell mediated cytotoxicity