Effect of charge-preserving mutations at D1, E5, and D6 on the pH sensitivity of Kv12.1 channel. (A–D) Normalized GV relations are shown for WT Kv12.1, D261E (D1E), E265D (E5D), and D314E (D6E) at bath pH 6, 7, and 8. Conductance was determined from isochronal tail currents recorded at −40 mV after 8-s steps to the indicated voltages; values show mean ± SEM (n = 4–8), and curves show single Boltzmann distribution fits. Fit parameters (V₅₀ and slope factor) are reported in Table 1.