Muscle contractions occur when a motor nerve impulse causes Ca²⁺ release from specialized compartments.To which regulatory protein does Ca²⁺ bind to initiate events that result in sliding of myosin thick filaments along actin thin filaments? A)myoglobin B)calmodulin C)troponin C D)Na⁺/K⁺ ATPase

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Quizplus · Accepted Answer

Ca²⁺ binds to troponin C, which in turn causes a conformational change in tropomyosin, exposing the myosin binding sites on actin and allowing for muscle contraction to occur. Myoglobin is a protein that stores oxygen in muscle tissue and is not directly involved in muscle contraction. Calmodulin is a regulatory protein that binds Ca²⁺ in other cellular processes, but not in muscle contraction. Na⁺/K⁺ ATPase is a sodium-potassium pump that maintains resting membrane potential, but is not involved in muscle contraction.

Muscle Contractions Occur When a Motor Nerve Impulse Causes Ca²⁺