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a complex of muscle proteins which, when combined with Ca++, influence tropomyosin to initiate contraction.
A globular protein of muscle that binds to tropomyosin and has considerable affinity for calcium ions; a central regulatory protein of muscle contraction. Troponin T binds to tropomyosin; troponin I inhibits F-actin-myosin interactions; troponin C is a calcium-binding protein and has a key role in muscle contraction.
A calcium-regulated protein, composed of three subunits, that is found in skeletal and cardiac muscle and regulates contraction by interacting with tropomyosin to control the binding of myosin to actin. Blood troponin levels are a biomarker for muscle damage, as in myocardial infarction.
A complex of three proteins, troponin-C (TnC), troponin-I (TnI), troponin-T (TnT), and present in striated muscle. Together, these proteins function as regulators of muscle contraction. Several isoforms exist. The cardiac isoform of TnT is specific for cardiac muscle; the blood level of TnT rises within 4 hours after myocardial damage and remains elevated for 10-14 days after an acute myocardial infarction (MI). Measurement of this protein is valuable in the early diagnosis of MI and in monitoring the effectiveness of thrombolytic therapy after an MI.