Cardiac and skeletal actin substrates uniquely tune cardiac myosin strain-dependent mechanics.

Cardiac ventricular myosin (βmys) translates actin by transducing ATP free energy into mechanical work during muscle contraction. Unitary βmys translation of actin is the step-size. and βmys regulates contractile force and velocity autonomously by remixing three different step-sizes with adaptive stepping frequencies.

Neural/Bayes network predictor for inheritable cardiac disease pathogenicity and phenotype.

The cardiac muscle sarcomere contains multiple proteins contributing to contraction energy transduction and its regulation during a heartbeat. Inheritable heart disease mutants affect most of them but none more frequently than the ventricular myosin motor and cardiac myosin binding protein c (mybpc3). These co-localizing proteins have mybpc3 playing a regulatory role to the energy transducing motor.

Auxotonic to isometric contraction transitioning in a beating heart causes myosin step-size to down shift.

Myosin motors in cardiac ventriculum convert ATP free energy to the work of moving blood volume under pressure. The actin bound motor cyclically rotates its lever-arm/light-chain complex linking motor generated torque to the myosin filament backbone and translating actin against resisting force. Previous research showed that the unloaded in vitro motor is described with high precision by single molecule mechanical characteristics including unitary step-sizes of approximately 3, 5, and 8 nm and their relative step-frequencies of approximately 13, 50, and 37%.

In vivo myosin step-size from zebrafish skeletal muscle.

Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the 'bottom-up' myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation.

In vitro and in vivo single myosin step-sizes in striated muscle.

Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains.