Key result
High Ca2+ enhances the c-open structural state of tropomyosin in native cardiac thin filaments.
The study provides high-resolution structures of native cardiac thin filaments, offering insights into the mechanism of cardiac muscle regulation by calcium.
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Refines molecular model of Ca2+-dependent thin filament regulation; leaves open translation to contractile therapies.
Risi et al. (2017) studied Cardiac muscle regulation (in vitro). High Ca2+ (activating conditions) vs. Low Ca2+ (relaxing conditions, pCa > 8) was evaluated on Structural position of tropomyosin on F-actin. Cryoelectron microscopy of native cardiac thin filaments reveals that tropomyosin exists in three structural states (c-blocked, c-closed, and c-open), with the c-open state significantly enhanced at high Ca2+ levels.
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