Which protein complex undergoes a conformational shift upon Ca²⁺ binding to expose the myosin-binding sites on actin?
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Correct answer: Troponin-tropomyosin complex
When Ca²⁺ binds to troponin C, the troponin–tropomyosin complex changes shape, moving tropomyosin away from actin’s myosin-binding sites, allowing cross-bridge formation.
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