Muscle Physiology: Contraction Mechanisms · Zoology

Which protein acts as a calcium sensor, undergoing a conformational change when $Ca^{2+}$ binds to it?

  1. Actin thin filament
  2. Myosin thick filament
  3. Troponin complex
  4. Titin elastic protein
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Correct answer: Troponin complex

Troponin is a three-polypeptide complex; one part (Troponin C) has a high affinity for calcium ions. Upon binding, it pulls tropomyosin off the binding sites, allowing contraction to proceed.

Difficulty: Medium Question 4 of 20

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