Which of the following statements regarding myosin in skeletal muscle is TRUE? A) Myosin cross-bridge heads contain two binding sites, one for actin and one for tropomyosin. B) Myosin is an ATPase. C) The rate of ATP hydrolysis by myosin is the same in all types of skeletal muscle. D) All of the myosin cross-bridge heads in a thick filament are oriented and rotate in the same direction. E) Troponin covers the binding site on myosin molecules until Ca²⁺ binds to troponin to remove it from its blocking position.

Question

Quizplus · Accepted Answer

Myosin is an ATPase, meaning it catalyzes the hydrolysis of ATP to release energy for muscle contraction. The other statements are false; the myosin cross-bridge heads have only one binding site for actin, the rate of ATP hydrolysis varies among muscle types, the orientation and rotation of myosin cross-bridge heads is staggered in a thick filament, and troponin regulates the interaction between actin and myosin, not tropomyosin.

Which of the Following Statements Regarding Myosin in Skeletal Muscle