The structure of the native cardiac thin filament at systolic Ca²⁺ levels.

ABSTRACT: Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca²⁺ levels. Thin filaments are comprised of two actin strands, each harboring equally separated troponin complexes, which bind Ca²⁺ to move tropomyosin cables away from the myosin binding sites and, thus, activate systolic contraction. Recently, structures of thin filaments obtained at low (pCa ∼9) or high (pCa ∼3) Ca²⁺ levels revealed the transition between the Ca²⁺-free and Ca²⁺-bound states. However, in working cardiac muscle, Ca²⁺ levels fluctuate at intermediate values between pCa ∼6 and pCa ∼7. The structure of the thin filament at physiological Ca²⁺ levels is unknown. We used cry

SUBMITTER: Risi CM 

PROVIDER: S-EPMC8020778 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature