MD-based steering of myosin from its pre-powerstroke to its target post-powerstroke configuration triggers movement of tropomyosin pseudorepeats 4 and 6 from C-state to M-state positions. (A–D) Pre-powerstroke and post-powerstroke S1 interaction with actin subunits occurring next to tropomyosin pseudorepeat 4 (A and B) and tropomyosin pseudorepeat 6 (C and D) are displayed in the same format as in Fig. 2, A and B. During the pre- to post-powerstroke transition Loop-4 residues Arg 369 and Glu 370 must traverse the charged residues on tropomyosin highlighted in A and C, while in the post-powerstroke configuration they face Arg 133 and Lys 136 on pseudorepeat 4 (B) and Glu 212 and Lys 213 (D) on pseudorepeat 6 (also see Videos 2 and 3).