G-loop gate conformations and minimum distances. (A) Representative snapshots of the G-loop area at different time steps showing M319 and G318 as spheres and water molecules within 4 Å as sticks; a K⁺ ion is shown as a pink sphere. (B) Histograms with minimum distances between opposing subunits at the HBC gate (upper plot) and the G-loop gate (lower plot); residues A316 to T320 were included for analysis of the G-loop gate. The G-loop gate was wider than the average pore diameter during ion permeation (6.4 Å; see Table 2) in 55.4% of all simulation steps, as indicated by the hatched area. 11-µs data were included (unrestrained runs) for both plots.