Muscle Contraction · Histology

What is the specific role of ATP during the 'detachment' phase of the cross-bridge cycle?

  1. ATP binding to myosin causes its release from actin.
  2. ATP hydrolysis provides the energy for the power stroke.
  3. ATP binds to actin to make it more flexible.
  4. ATP is required to pump calcium back into the T-tubules.
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Correct answer: ATP binding to myosin causes its release from actin.

In the absence of ATP, the myosin head remains tightly bound to actin (rigor complex). When a new molecule of ATP binds to the myosin head, the affinity for actin decreases, allowing the head to detach.

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