Effect of gating charge mutations on DHA sensitivity. (A) Data for WT-IR. Structure of the Shaker K channel in the open state (based on the Kv1.2/2.1 chimera), with residues R362, R365, R368, and R371 in blue (left). One VSD and part of the pore domain are shown. Current traces at −40 mV (middle) and G-V curve fitted to Eq. 2 (right). V_1/2 = −43.5 and −53.2 mV, and s = 11.3 mV. (B) Data for R362⁻. Residue R362 are shown in red, and residues R365, R368, and R371 are shown in blue (left). Current traces at −35 mV (middle) and G-V curve fitted to Eq. 2 (right). V_1/2 = −36.8 and −34.9 mV, and s = 25.9 mV. (C) Data for R362⁺. Residues R362, R365, R368, and R371 are shown in blue (left). Current traces at −45 mV (middle) and G-V curve fitted to Eq. 2 (right). V_1/2 = −45.9 and −58.3 mV, and s = 13.1 mV. (D) Data for A359⁺. Residues A359, R362, R365, R368, and R371 are shown in blue (left). Current traces at −5 mV (middle) and G-V curve fitted to Eq. 2 (right). V_1/2 = −9.5 and −33.0 mV, and s = 18.1 mV. (E) Summary of experimental data for gating charge mutants. Data are expressed as mean ± SEM (n = 4–9).