troponin

A calcium-regulated protein occurring in three subunits in skeletal and cardiac muscle that, in conjunction with tropomysin, interacts with actin and myosin to facilitate muscle contraction. Blood troponin levels are a biomarker for muscle damage, as in myocardial infarction.

A complex of three regulatory proteins that is integral to muscle contraction in skeletal and cardiac muscle, or any member of this complex. The level of troponin in the blood is often used as an indicator of heart damage.