Reaction: Calcium Binds Troponin-C
- in pathway: Striated Muscle Contraction
Troponin (Tn) is the central regulatory protein of striated muscle contraction. Tn consists of three components: troponin I (TNNI3; the inhibitor of actomyosin ATPase), Tn-T (which contains the binding site for tropomyosin) and troponin C (TNNC1, Tn-C). The binding of calcium to TNNC1 abolishes the inhibitory action of Tn on actin filaments. At the start of the striated muscle contraction cycle, a myosin head lacking a bound nucleotide is locked tightly onto an actin filament in a rigor conformation. TNNC1 binds four calcium ions. In an actively contracting muscle this state is very short-lived, being rapidly terminated by the binding of a molecule of ATP.
Reaction - small molecule participants:
Ca2+ [cytosol]
Reactome.org reaction link: R-HSA-390595
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Reaction input - small molecules:
calcium(2+)
Reaction output - small molecules:
Reactome.org link: R-HSA-390595