| Modification Notes |
Myosin IXb, also designated Myosin 9B, MYO9B, CELIAC4 and MYR5, is a single-headed myosin that moves processively on Actin filaments in the minus-end direction, making it the first myosin superfamily member identified that travels in the reverse direction. Isolated cDNAs of human Myosin IXB from liver and small intestine libraries encode a 2,022 amino acid protein that maps to chromosome 19p13.1. Studies indicate that Myosin IXb binds calmodulin through IQ motifs situated in its neck domain and, like other CALM1-containing myosins, exhibits maximal velocity of Actin filaments in the absence of calcium, contains putative calmodulin light chains and is a calcium-regulated, mechanochemically active motor that demonstrates Rho GAP activity. Research has shown a significant and replicable association of celiac disease to a common irregularity located in intron 28 of the myosin IXBgene, which encodes an atypical myosin molecule that functions in the remodeling of Actin in epithelial enterocytes. Individuals homozygous with respect to the at-risk allele have a 2.3-times higher risk of celiac disease. |