Single molecule analysis of the actomyosin motor.

Progress in imaging techniques and nano-manipulation of single molecules has been remarkable. These techniques have allowed the accurate determination of myosin-head-induced displacements and of how the mechanical cycles of the actomyosin motor are coupled to ATP hydrolysis. This has been achieved by measuring mechanical and chemical events of actomyosin directly at the single molecule level. Recent studies have made detailed measurements of myosin step size and mechanochemical coupling. The results of these studies suggest a new model for the mechanism of motion underlying actomyosin motors, which differs from the currently accepted lever-arm swinging model.