Getting a Grip on Myosin Review

The biochemistry of muscle contraction is taught in every introductory biology class, and hence many people believe that myosin force transduction is well understood. How-ever, although it is firmly established that actin and myosin filaments slide past one another in a muscle sarcomere, the molecular mechanism of myosin motility has become a subject of increasing controversy. The debate has been fueled, in part, by measurements of how far myosin can move along an actin filament during one round of ATP hydrolysis. Values varying from 5 to 200 nm per ATP have emerged from such studies, and, not surprisingly, radically different models of myosin-based movement have been presented to account for these results. The wide variation of myosin step size estimates very likely stems from the fact that the measurements wer