Troponin I (TnI) is 1 of 3 subunits, along with troponin C (TnC) and Troponin T (TnT) of troponin complex found in cardiac (cTnI) and fast skeletal (fsTnI) muscle (Noland et al, 1995). Protein kinase C-mediated phosphorylation of cardiac myofilament proteins has been shown to depress the actomyosin interaction and may be important during heart failure. (Montgomery et al, 2002) Studies indicate that phosphorylation of Ser43 and Ser45 of cardiac troponin I plays a substantial role in the PKC-mediated depression. (Montgomery et al, 2002).
