Troponin is a complex of three regulatory proteins that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle. Discussions of troponin often pertain to its functional characteristics and/or to its usefulness as a diagnostic marker for various heart disorders. Synonyms: Polyclonal Troponin I (cardiac) antibody, Anti-Troponin I antibody (cardiac), Troponin I antibody (cardiac).