Troponin: Structure, properties, and mechanism of functioning

This review discusses the structure and properties of the isolated componen ts of troponin, their interaction, and the mechanisms of regulation of cont ractile activity of skeletal and cardiac muscle. Data on the structure of t roponin C in crystals and in solution are presented. The Ca2+-induced confo rmational; changes of troponin C structure are described. The structure of troponin I is analyzed and its interaction with other components of actin f ilaments is discussed. Data on phosphorylation of troponin I by various pro tein kinases are presented. The role of troponin I phosphorylation in the r egulation of contractile activity of the heart is analyzed. The structural properties of troponin T and its interaction with other components of thin filaments are described. Data on the phosphorylation of troponin T are pres ented and the effect of troponin T phosphorylation on contractile activity of different muscles is discussed. Modern models of the functioning of trop onin are presented and analyzed.