UNCONVENTIONAL MYOSINS

Myosins are molecular motors that upon interaction with actin filament s convert energy from ATP hydrolysis into mechanical force. Evidence h as emerged for the existence of a large, widely expressed and evolutio narily ancient superfamily of myosin genes. In addition to the well-ch aracterized conventional, filament-forming, two-headed myosin-II of mu scle and nonmuscle cells, at least ten additional classes of myosins h ave been identified. In vertebrates, at least seven of the eleven clas ses are expressed, and many myosins car, be expressed in a single cell type. This review summarizes known structural and functional features of these novel unconventional myosins.