Влияние сердечного миозин-связывающего белка С на характеристики одиночного актин-миозинового взаимодействия в миокарде

Abstract

. Myocardial contraction is the result of the interaction of myosin, which makes up the thick filament, with actin, which forms the basis of the thin filament, and is regulated by calcium through the regulatory proteins troponin and tropomyosin. Recently, it was found that, in addition to regulatory proteins, cardiac myosin-binding protein-C (cMyBP-C) is involved in the regulation of actin-myosin interaction. cMyBP-C is one of the integral proteins of the cardiomyocyte sarcomere, which has binding sites for the main sarcomere proteins, myosin, actin, and tropomyosin. cMyBP-C controls the number of myosin heads interacting with the thin filament and participates in its activation. In this work, the influence of cMyBP-C on the characteristics of a single actin-myosin interaction, myosin step size and interaction duration, was studied using an optical trap method. Cardiac myosin was extracted from rabbit left ventricular myocardium, actin was isolated from rabbit fast skeletal muscle, and cMyBP-C was obtained from chicken ventricles. cMyBP-C was added to cardiac myosin in a physiological ratio of 1:5. In an in vitro motility assay, the addition of cMyBP-C was found to slow actin sliding velocity over myosin by 30%. It was found that cMyBP-C does not affect step size of myosin but increases the duration of its interaction with the actin filament. The results obtained indicate a direct effect of cMyBP-C on a single actin-myosin interaction.