(A) Superposition of the strong-ADP (orange) and rigor (red) atomic models. Changes at the active site (black box) are not transmitted to the actomyosin interface, but to the N-terminal and converter domain, resulting in a lever swing of 9°. (B) Close-up view of the active site showing the structural rearrangements upon Mg2+-ADP release (indicated by black arrows). The rigor structure is shown as transparent; see Figure 1 for color code. (C) Illustration of domain movements associated with Mg2+-ADP release predicted by DynDom (Hayward and Lee, 2002). Identified domains correlate well with myosins structural domains (see Figure 1—figure supplement 6) with domain 1 (yellow, 452 residues), domain 2 (181 residues, blue), and domain 3 (93 residues, red) representing the L50 and U50 domains, the N-terminal domain, and the converter domain, respectively. Bending residues primarily localize to the P-loop, the A-loop, and the central transducer β-sheet (1–2, green), as well as to a small part of the N-terminal and converter domain (2–3, purple). (D) Scheme illustrating the structural changes associated with Mg2+-ADP release. (E) Same views as in (D), but colored by DynDom domains, also see (C). The HF helix and the lever arm are highlighted by a black and a yellow arrowhead, respectively. Models were aligned on F-actin. See Figure 3—video 1 for a three-dimensional visualization.