Troponin Structural Dynamics in the Native Cardiac Thin Filament Revealed by Cryo Electron Microscopy.

ABSTRACT: Cardiac muscle contraction occurs due to repetitive interactions between myosin thick and actin thin filaments (TF) regulated by Ca²⁺ levels, active cross-bridges, and cardiac myosin-binding protein C (cMyBP-C). The cardiac TF (cTF) has two nonequivalent strands, each comprised of actin, tropomyosin (Tm), and troponin (Tn). Tn shifts Tm away from myosin-binding sites on actin at elevated Ca²⁺ levels to allow formation of force-producing actomyosin cross-bridges. The Tn complex is comprised of three distinct polypeptides - Ca²⁺-binding TnC, inhibitory TnI, and Tm-binding TnT. The molecular mechanism of their collective action is unresolved due to lack of comprehensive structural information on Tn region of cTF. C1 domain of cMyBP-C activates cTF in the absen

SUBMITTER: Risi CM 

PROVIDER: S-EPMC11007730 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature