Major histocompatibility complex class I polypeptide-related sequence B (MICB)

Major histocompatibility complex class I polypeptide-related sequence B (MICB) is a non-classical MHC class I-like transmembrane glycoprotein encoded by the MICB gene within the MHC locus on human chromosome 6[6][2]. Structurally, MICB has three extracellular domains (α1, α2, α3), a transmembrane segment, and a cytoplasmic tail, similar to classical MHC class I molecules, but does not bind β2-microglobulin or peptides[2][6][3]. Expression of MICB is strongly induced by cellular stress, such as heat shock, infection, or cancer. Its main known function is to serve as a ligand for the activating immune receptor NKG2D, found on natural killer (NK) cells and some T cell subtypes, leading to immune recognition and lysis of stressed or transformed cells[2][3][6]. MICB is implicated in anti-tumor and anti-viral responses, and its aberrant expression is linked to several diseases, particularly cancers and inflammatory conditions. Therapeutic approaches that target MICB or its interaction with NKG2D are under investigation, but no approved drug directly targets MICB as of 2024[2][3][6].

Other names

MHC class I-related chain BMHC class I polypeptide–related sequence BMICB

Antibody-based agents: block interaction between MICB and NKG2D to modulate immune activation NKG2D-targeted: agonists/antagonists affecting NK cell and cytotoxic T cell-mediated cytotoxicity through ligand engagement