Single fluorophore imaging of Myosin V revealed alternating step sizes of 37 + 2x nm and 37 - 2x nm, strongly supporting a hand-over-hand model of motility rather than an inchworm model.
Myosin V is a dimeric molecular motor that moves processively on actin, with the center of mass moving approximately 37 nanometers for each adenosine triphosphate hydrolyzed. We have labeled myosin V with a single fluorophore at different positions in the light-chain domain and measured the step size with a standard deviation of <1.5 nanometers, with 0.5-second temporal resolution, and observation times of minutes. The step size alternates between 37 + 2x nm and 37 - 2x, where x is the distance along the direction of motion between the dye and the midpoint between the two heads. These results strongly support a hand-over-hand model of motility, not an inchworm model.
Yıldız et al. (Mon,) conducted a other in Myosin V motility. Single fluorophore labeling was evaluated on Step size of Myosin V. Single fluorophore imaging of Myosin V revealed alternating step sizes of 37 + 2x nm and 37 - 2x nm, strongly supporting a hand-over-hand model of motility rather than an inchworm model.