Myosin's powerstroke transitions define atomic scale movement of cardiac thin filament tropomyosin.

ABSTRACT: Dynamic interactions between the myosin motor head on thick filaments and the actin molecular track on thin filaments drive the myosin-crossbridge cycle that powers muscle contraction. The process is initiated by Ca2+ and the opening of troponin-tropomyosin-blocked myosin-binding sites on actin. The ensuing recruitment of myosin heads and their transformation from pre-powerstroke to post-powerstroke conformation on actin produce the force required for contraction. Cryo-EM-based atomic models confirm that during this process, tropomyosin occupies three different average positions on actin. Tropomyosin pivoting on actin away from a TnI-imposed myosin-blocking position accounts for part of the Ca2+ activation observed. However, the structure of tropomyosin on thin filaments that follows pre-p

SUBMITTER: Rynkiewicz MJ 

PROVIDER: S-EPMC11010328 | biostudies-literature | 2024 May

REPOSITORIES: biostudies-literature