As part of an experiment, radiolabeled ATP is injected into skeletal muscle. During muscle contraction, the labeled ATP is observed to attach to the sarcomere. This attachment causes immediate:

Question

As part of an experiment, radiolabeled ATP is injected into skeletal muscle.  During muscle contraction, the labeled ATP is observed to attach to the sarcomere.  This attachment causes immediate:

Quizplus · Accepted Answer

11ec160b_3d02_6101_9249_1d3190c01cfe_MD0001_00 According to the model posited by Rayment et al., the role of ATP in skeletal and cardiac muscle contraction may be to release the myosin head from its actin binding site and then to energize a conformational change that resets the myosin head to "contract" again the next time it binds to actin. (Choices A and B) Calcium binding to troponin C shifts tropomyosin away from the myosin binding site on actin. These steps do not depend directly on ATP. (Choice D) If ATP is not available, the cross-bridge between myosin and actin will persist (rigor mortis). (Choice E) Myosin light chain kinase phosphorylates the myosin light chain, activating myosin to bind actin filaments in smooth muscle cells. There is no myosin head phosphorylation by a specific kinase in skeletal muscle contraction. Educational Objective: During the skeletal muscle contraction cycle, ATP binding to myosin causes release of the myosin head from its binding site on the actin filament.

As Part of an Experiment, Radiolabeled ATP Is Injected into Skeletal