Troponin I is part of a heteromeric thin filament regulatory complex that is responsible for modulating skeletal and cardiac muscle contraction. Troponin complex consists of three subunits: troponin I (TnI), troponin T (TnT), and troponin C (TnC). Each of these subunits has a different role in the function of the complex. In particular, TnI is the inhibitory component, and confers calcium-sensitivity to the ATPase activity of the myofibril contractile apparatus within striated muscles. By blocking actin-myosin interactions, it regulates muscle relaxation.
