How does ATP allow myosin to detach from actin?

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Diagram showing the structure of human striated or skeletal muscle, with labeled cross-sections from whole muscle to fascicle, muscle fiber, myofibril, and sarcomere, highlighting actin and myosin filaments. — muscle The structure of striated, or skeletal, muscle. Striated muscle tissue, such as the tissue of the human biceps muscle, consists of long fine fibers, each of which is in effect a bundle of finer myofibrils. Within each myofibril are filaments of the proteins myosin and actin; these filaments slide past one another as the muscle contracts and expands. On each myofibril, regularly occurring dark bands, called Z lines, can be seen where actin and myosin filaments overlap. The region between two Z lines is called a sarcomere; sarcomeres can be considered the primary structural and functional unit of muscle tissue.

In the process of muscle contraction, ATP plays a critical role in the interaction between the protein filaments actin and myosin.

Specifically, the binding of an ATP molecule to the myosin head causes it to detach from the actin filament. Once this detachment occurs, the subsequent breakdown (hydrolysis) of the ATP molecule releases the energy necessary to reposition the myosin head, preparing it for the next contraction cycle.1

This cycle is essential for muscle function, as the continuous attachment and detachment of myosin cross-bridges allow for the sliding of filaments that results in muscle shortening. Additionally, ATP is required to pump calcium ions back into storage within the sarcoplasmic reticulum, which allows the muscle to relax after contraction.231