Troponin, working in conjunction with tropomyosin, functions as a molecular switch, regulating muscle contraction in response to changes in the intracellular Ca2+ concentration. Troponin consists of three subunits: the Ca2+-binding subunit troponin C (TnC), the tropomyosin-binding subunit troponin T (TnT), and the inhibitory subunit troponin I (TnI).Troponin T type 2 (cTnT,TNNT2) is a cardiac troponin T isoform expressed in the human heart, that is essential for calcium-regulated myofibrillar ATPase activity. Assays for measuring serum concentrations of cTnT, as well as cTnI, have been reported for analyzing cardiac injury.