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What is the role of Ca2+ in the control of muscle contraction? a. It causes depolarization...

What is the role of Ca2+ in the control of muscle contraction?

a. It causes depolarization of the T tubule system.

b. It binds to tropomyosin and breaks actin–myosin cross-bridges.

c. It changes the conformation of troponin, which ultimately results in myosin-binding sites being exposed.

d. It changes the conformation of myosin heads, causing actin and myosin filaments to slide past each other.

e. It blocks the ATP-binding site on myosin heads, enabling muscles to relax.

Science   Anatomy-And-Physiology   
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Option C) It changes the conformation of troponin, which ultimately results in myosin-binding sites being exposed.

  • Tropomyosin is the protien that blocks myosin binding sites on actin.
  • Calcium ions binds to troponin that is attached to tropomyosin.
  • Binding of calcium leads to change in conformation of the troponin. As a result, tropomyosin moves away from the myosin binding sites on actin.
  • As the sites gets exposed, cross bridge formation occurs as a part of muscle contraction cycle.
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