Tropomyosin translocation over actin during MD when started in the open M-state configuration. Shown is the surface of two actin monomers as a gray surface with residue Pro 333 highlighted in blue. Actin monomers shown in all panels are from the pre-MD minimized structure. Tropomyosin structures at indicated simulation time steps are shown as green ribbons. The relative azimuthal positions of tropomyosin in the open M state, closed C state, and blocked B state are indicated by the green, yellow, and red lines, respectively. Note that the constraints used during the simulation preserve the general shape of tropomyosin throughout and that the tropomyosin moves toward the B state early in the simulation.