troponin

(trō′pŏ-nĭn )

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ABBR: Tn An inhibitory protein in muscle fibers. The action potential at the sarcolemma causes the sarcoplasmic reticulum to release calcium ions, which bond to troponin and shift tropomyosin away from the myosin-binding sites of actin, permitting contraction.
SEE: muscle for illus

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