K⁺ radial distribution functions from spontaneous K⁺-binding simulations. (A–C) Radial distribution of K⁺ ions around the C_γ atom of D454 in the trajectories corresponding to Fig. 1, C–E. (D–F) Radial distribution of K⁺ ions around the C_δ atom of E373 in the trajectories corresponding to Fig. 1, F–H. The insets show the radial disctribution function with the y axis magnified, illustrating the small contribution to the distribution at larger distances.