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. cTnI is phosphorylated by protein kinase C and protein kinase A at Ser23/24 (Noland et al, 1995) and is phosphorylated by AMPK at Ser23 and Ser150 (Solis et al, 2011). Evidence suggests that AMPK, a critical regulator of cardiac energetics, prefers phosphorylating Ser150 over Ser23, and may play a role in regulating energy consumption through altering the phosphorylation status of cTnI (Solis et al., 2011).
