Unconventional myosin-Ia (MYO1A)

Unconventional myosin-Ia (MYO1A) is a monomeric, actin-based motor protein belonging to the myosin superfamily, specifically the class I myosins[3][5]. MYO1A is most abundantly expressed in enterocytes—the absorptive epithelial cells that line the small intestine—where it localizes to the apical brush border microvilli and plays a critical role in maintaining the tightly organized structure and membrane-cytoskeleton cohesion of this compartment[1][2][3]. Its primary molecular activities include directing membrane-associated organelle movement along actin filaments, contributing to the proper organization of microvillar membranes, and regulating tension and stability of the brush border through its interactions with actin and acidic phospholipids in the membrane[1][2][3][5]. MYO1A contains the conserved N-terminal myosin motor domain (responsible for ATP-driven mechanical movement), a neck region with calmodulin-binding IQ motifs (involved in calcium signaling and stabilization), and a unique C-terminal tail (essential for membrane targeting and protein interactions)[3][2]. Loss of MYO1A disrupts brush border architecture, resulting in defects in microvillar morphology, mislocalization of membrane and cytoskeletal proteins, and functional compensation by related class I myosins, like myosin-1c[1]. Mutations in MYO1A have been linked to diseases such as autosomal dominant non-syndromic hearing loss (DFNA48) and certain forms of congenital diarrhea[5]. There are no known approved drugs, biomarker roles, or safety concerns currently associated with MYO1A, and it is not considered a classical therapeutic target (such as an enzyme, receptor, an ion channel, or transporter), but rather a structural and functional cytoskeletal motor protein[5][3].

Other names

brush border myosin Imyosin I heavy chainMYHLBBM-IBBMIMIHCDFNA48DIAR15myosin, heavy polypeptide-like (100kD)myosin, heavy polypeptide-like 110kDa