Mutants at residue 1784 alter gating current voltage dependence. (A1) Sample gating currents recorded with the activation protocol described in the text. (A2) Sample gating currents recorded with the deactivation protocol described in the text. (B) Average voltage dependence of gating charge activation for residue 1784 mutants recorded at extracellular pH 7.4 (n = 4–6). Outward QVs were determined by integrating the charge moved during depolarizations between −150 and +60 mV (a) from a holding potential of −150 mV. (C) Average voltage dependence of gating charge deactivation for residue 1784 mutants recorded at extracellular pH 7.4 (n = 4–5). To measure the voltage dependence of gating current deactivation, cells were hyperpolarized to membrane potentials between −150 and +20 mV (b) following a depolarization pulse to +50 mV (a). This was followed by depolarization to +50 mV (c). (D) Average midpoints of gating charge activation and deactivation for residue 1784 mutants at extracellular pH 7.4 (n = 4–6; Tables S6 and Table S7). Error bars are SEM.