Fig. 6. Schematic comparison of the principal structural rearrangements in-between crystal structures and TR-XSS models.

The prepulse state shows reduced opening of the cytoplasmic domains, the intermediate TR-XSS model is similar to a [Ca₂]E1ATP state, and displacement of the A domain in the late TR-XSS model exposes the ADP site, but with the N domain not yet in a E2 position. Protein color coding is as in Fig. 1, the ATP and ADP are displayed as four and three purple pentagons, the TGES motif is represented by a green rectangle, the phosphorylated aspartic acid is colored yellow, and the calcium ions are depicted as green circles.