PHYSIOLOGY
SYNAPTIC PHYSIOLOGY
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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actin
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troponin
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tropomyosin
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myosin
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Detailed explanation-1: -In striated muscle, calcium causes a shift in the position of the troponin complex on actin filaments, which exposes myosin-binding sites (Fig. 2A). Myosin bound by ADP and inorganic phosphate (Pi) can then form cross-bridges with actin, and the release of ADP and Pi produces the power stroke that drives contraction.
Detailed explanation-2: -The calcium ions released from endoplasmic reticulum72) bind to the calcium-binding subunit of troponin (troponin-C (TnC), ∼18 kDa), and the inhibition by troponin is neutralized to trigger muscle contraction.
Detailed explanation-3: -When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites. The sarcoplasmic reticulum stores calcium ions, which it releases when a muscle cell is stimulated; the calcium ions then enable the cross-bridge muscle contraction cycle.
Detailed explanation-4: -Abstract. Troponin (Tn) is the sarcomeric Ca2+ regulator for striated (skeletal and cardiac) muscle contraction. On binding Ca2+ Tn transmits information via structural changes throughout the actin-tropomyosin filaments, activating myosin ATPase activity and muscle contraction.