InterPro: IPR003608 MIR

The MIR domain is named after three of the proteins in which it occurs: protein Mannosyltransferase (EC:2.4.1.109), Inositol 1,4,5-trisphosphate receptor (IP3R) and Ryanodine receptor (RyR). MIR domains have also been found in eukaryotic stromal cell-derived factor 2 (SDF-2) and in Chlamydia trachomatis protein CT153. The MIR domain may have a ligand transferase function. This domain has a closed beta-barrel structure with a hairpin triplet, and has an internal pseudo-threefold symmetry. The MIR motifs that make up the MIR domain consist of ~50 residues and are often found in multiple copies.

Inositol 1,4,5-trisphosphate (InsP3) is an intracellular second messenger that transduces growth factor and neurotransmitter signals. InsP3 mediates the release of Ca²⁺ from intracellular stores by binding to specific Ca²⁺ channel-coupled receptors. Ryanodine receptors are involved in communication between transverse-tubules and the sarcoplamic reticulum of cardiac and skeletal muscle. The proteins function as a Ca²⁺-release channels following depolarisation of transverse-tubules [1]. The function is modulated by Ca²⁺, Mg2+, ATP and calmodulin. Deficiency in the ryanodine receptor may be the cause of malignant hyperthermia (MH) and of central core disease of muscle (CCD) [2]. protein O-mannosyltransferases transfer mannose from DOL-P-mannose to ser or thr residues on proteins.