Thin myofilaments of a muscle consists of three different proteins-actin, tropomyosin and troponin. Actin occur in two forms: G-actin and F-actin. Tropomyosin is a fibrous molecule that attaches to F-actin in the groove between its filaments. Troponin is a complex of 3 polypeptides. Troponin
(T) binds to tropomyosin as well as to the other two troponin components. Troponin I inhibits the F-actin-myosin interaction and also binds to other components of troponin.