Question

A single myosin head moves an actin filament about 10 nm in a single power stroke, yet the myosin head itself only experiences a 0.5 nm conformational change while attached to the actin filament. How does such a small conformational shift in the myosin head translate into such a large displacement of the actin filament? A) The small head movement is expanded elastically. B) Interaction with the myosin head causes the actin filament to stretch. C) Interaction with the myosin head causes the actin filament to become shorter. D) The small myosin head movement was amplified ~20-fold by the swinging movement of an adjoining, elongated alpha-helical neck that acts like a lever arm. E) The small myosin head movement was amplified about 20-fold by the swinging movement of an adjoining, elongated beta-pleated sheet neck that acts like a lever arm.