Time evolution of the interatomic distances between the associating calcium ion and the oxygen atoms of key stabilizing residues from the C-loop and F-loop of the wild-type α7/AChBP during the course of MD simulation. (a–e) Results for four associating calcium ions are shown, while results for the fifth calcium ion are shown in Fig. 4 d of the main text. (d) For one of the binding sites, two trajectories are shown, one for the first calcium that binds and then dissociates (a) and the other for the second calcium that binds shortly after the first calcium dissociates (b).