Fig. 3

Negative logarithmic densities of K⁺ ions inside the SF of MthK. Densities can be treated as approximate free energy profiles with minima corresponding to ion binding sites and maxima being energy barriers between them. Data for several levels of opening are presented from the main set of simulations (restrains applied to the ends of TM helices), for both a AMBER and b CHARMM force fields, as a function of distance along the SF main axis. Colors represent opening levels and correspond to Fig. 1. C—pink/red: non-conductive (closed) channels; cyan/blue: open channels; green: maximally open channels. Openings for which the highest outward K⁺ current was recorded are marked with *max current. Error bars represent 95% confidence intervals. Source data are available as a Source Data file.