troponin complex
Last reviewed 04/2022
Troponin is an important component of the contractile machinery of skeletal and cardiac muscle. Troponin is a complex of three polypeptide chains:
- Troponin C (18 kd)
- Troponin I (24 kd)
- Troponin T (37 kd)
Troponin C binds calcium, Troponin I binds actin, Troponin T binds tropomyosin.
The troponin complex is located in the thin filaments at intervals set by the length of a tropomyosin unit. Each troponin complex regulates the interactions of 7 actin units.
During skeletal and cardiac muscle contraction the binding of calcium to Troponin C induces a conformational change which is transmitted to other members of the troponin complex and then to tropomyosin resulting in shortening of the actin-myosin complex and muscle contraction.