InterPro domain: IPR016093

The MIR domain is named after three of the proteins in which it occurs: protein Mannosyltransferase ( 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) [ 1 ] 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 Ca ²⁺ from intracellular stores by binding to specific Ca ²⁺ 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 Ca ²⁺ -release channels following depolarisation of transverse-tubules [ 2 ]. The function is modulated by Ca ²⁺ , 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) [ 3 ]. protein O-mannosyltransferases transfer mannose from DOL-P-mannose to ser or thr residues on proteins.

1. Endoplasmic reticulum proteins SDF2 and SDF2L1 act as components of the BiP chaperone cycle to prevent protein aggregation. Genes Cells 22, 684-698
2. Unique phosphorylation site on the cardiac ryanodine receptor regulates calcium channel activity. J. Biol. Chem. 266, 11144-52
3. Mutation screening of the RYR1 gene in malignant hyperthermia: detection of a novel Tyr to Ser mutation in a pedigree with associated central cores. Genomics 23, 236-9