Myosin VI: Roles for a minus End-Directed Actin Motor in Cells

The recent discovery that the class VI myosin is minus end-directed (Schliwa 1999; Wells et al. 1999) allows new mechanisms of actin-based motility to exist in cells. This will prompt reexamination of a broad range of cell movements previously difficult to explain by conventional force generating mechanisms. Myosins are a large family of molecular motor proteins divided into 15 or more classes, and are the only known type of actin-based motor. Intrinsically, an individual myosin converts energy derived from ATP hydrolysis into unidirectional movement towards only one specified end of an actin filament: either the plus (barbed-) or minus (pointed-) end. Minus end directionality in myosin VI is unique: all other myosins tested are plus end-directed actin motors. Myosin VI plays a key role in cell motility and shape change events in many animal species (...