What happens to the myosin head after the power stroke?

After the power stroke, the myosin head binds to a new ATP molecule. This binding is essential for the muscle contraction cycle to continue. When the myosin head is attached to actin during the power stroke, it pulls the actin filament towards the center of the sarcomere. Following this action, the myosin head must detach from the actin in order to reset for another contraction cycle.

The binding of ATP to the myosin head is crucial because it causes a conformational change that reduces the affinity of myosin for actin, allowing the myosin head to release from the actin filament. This detachment is necessary for the next steps in the contraction cycle to occur, as it prepares the myosin for another binding to actin upon hydrolysis of ATP, which re-cocks the myosin head. By considering these processes, it’s evident that the role of ATP binding is a critical component of muscle functioning and the continuation of the contraction cycle.