Figure 3.

The myosin mechanochemical cycle and its regulation. For simplicity, only one myosin head is shown. In the super relaxed state (SRX, blue shaded box), myosin is autoinhibited. Force and RLC phosphorylation each promote the adoption of the disordered relaxed state (DRX). The thin filament can lie in the blocked, closed, or open states, where switching between states depends on calcium and myosin binding. In the open state, myosin can bind to and detach from the thin filament in a nucleotide-dependent manner. Bound and detached states are indicated by yellow and red shading, respectively. Force-dependent steps are indicated by red arrows. Mechanical substeps of the working stroke and structural states (pre-power stroke and post-power stroke) are labeled.