Fig. 2.

(A) Three-dimensional map of the view in Fig. 1B showing a full 429-Å repeat together with fitting of the atomic model of myosin heads in the off state to the head motifs in crowns 2, 3, and 1 after splitting and fitting separately the two heads from Alamo et al. (10). The majority of the atomic structures for the head pairs is well-contained within the density map on crowns 3 and 1 but less on crown 2, especially for the two lever-arm parts. The S2 is also fitted, as described in the text. (B) Same view as in A, but shown without the back part of the map to illustrate the fitting of the heads and S2 within the densities on levels 2, 3, and 1. S2 is shown in red and the bare-zone direction is toward the bottom.