Figure 3. Blebbistatin pocket opening preferentially occurs in the ADP*Pi state.

(A) Distributions of skeletal muscle myosin IIA blebbistatin pocket volumes in the ATP-bound state and ADP*Pi-bound state demonstrate that the blebbistatin pocket is more likely to open in the ADP*Pi-bound state, consistent with biochemical experiments which predict tighter binding between blebbistatin and myosin when myosin is bound to ADP*Pi. (B) The probability of adopting compatible structures (i.e. structures with pocket volumes equal to or greater than the blebbistatin-bound crystal structure) is higher when myosin is bound to ADP and phosphate. Error bars represent estimate of standard error of the mean from 250 trials of bootstrapping where trajectories were drawn with replacement from the entire dataset (see Materials and methods). Note that reported pocket volumes are smaller than the space available to ligands because of an algorithm choice made to avoid erroneous detection of small pockets (see Materials and methods for details).