MYO1

MYO1 refers to the class I myosins, a subgroup of the myosin superfamily consisting of single-headed, actin-based motor proteins. They are considered unconventional myosins, in contrast to the dimeric, filament-forming class II myosins. Class I myosins couple ATP hydrolysis to movement along actin filaments and often function at membrane–cytoskeleton interfaces rather than forming large motor complexes.

In humans, the MYO1 gene family includes MYO1A, MYO1B, MYO1C, MYO1D, MYO1E, and MYO1F. These genes encode isoforms that share a conserved N-terminal motor domain and a neck region that binds light chains, followed by a tail that mediates cargo interactions with membranes or organelles. Some isoforms contain pleckstrin homology (PH) or other lipid-binding regions, enabling association with specific membrane surfaces. The motor moves toward the plus end of actin filaments and can act as a transporter, an anchor, or a regulator of membrane tension, depending on the cellular context and binding partners.

Functions and localization vary by isoform and organism but commonly include roles in endocytosis and vesicle trafficking, plasma membrane remodeling, and regulation of membrane tension. Class I myosins are distributed across many tissues in diverse organisms, with expression patterns reflecting specialized cellular tasks such as nutrient uptake in epithelia or membrane dynamics in neural and sensory cells.

Clinical notes: mutations or altered regulation of certain MYO1 family members have been associated with human diseases, including forms of hereditary deafness and disorders affecting membrane trafficking, though the specific effects are isoform- and context-dependent. Research continues to elucidate the precise functions of each MYO1 gene in health and disease.