Troponin: Composition, Function, and Role in Muscle Contraction

Troponin is a complex of three proteins: troponin C, troponin I, and troponin T. Troponin C binds to calcium ions, troponin I inhibits the interaction between actin and myosin, and troponin T binds to tropomyosin. The molecular composition of troponin is:

* Troponin C: 18 kDa, calcium-binding protein

* Troponin I: 24 kDa, inhibitory protein

* Troponin T: 37 kDa, tropomyosin-binding protein

The troponin complex is located on the thin filaments of skeletal and cardiac muscle. When calcium ions bind to troponin C, it causes a conformational change in the troponin complex that allows myosin to bind to actin and initiate muscle contraction.