Figure 1.

The cTn complex plays an essential role in cardiomyocyte contraction. When an action potential reaches the cardiomyocyte, calcium enters the cell, leading to a conformational change after binding of calcium ions to the TnC subunit. Hence, the myosin binding sites are exposed, allowing the myosin head to bind to the actin filaments and facilitating cardiomyocyte contraction. Note that the majority of cTn complexes are bound to the actin filament but are also present in an early releasable pool. cTn indicates cardiac troponin.