Charge-dependent DHA sensitivity. (A) Normalized representative current traces for voltages corresponding to 10% of Gmax in control solution at pH 7.4. Black and gray traces indicate control solution for A359R/R362Q and A359E/R362Q, respectively (normalized to 1), blue trace denotes 70 µM DHA on A359R/R362Q, and red trace denotes 70 µM DHA on A359E/R362Q. (B) DHA-induced G(V) shifts for the channels in A. 70 µM DHA at pH 7.4. R362Q is included for comparison. Mean ± SEM (n = 7, 12, and 9). DHA-induced shifts are compared by one-way ANOVA together with Bonferroni post-hoc test: *, P < 0.05; ***, P < 0.001. (C) As in A. Red trace for L361E/R362Q and blue trace for L361R/R362Q. (D) As in B (n = 9, 12, and 14). (E) As in B (n = 7, 12, and 10; **, P < 0.01). (F) Cartoon to qualitatively explain data in A–E. Figures denote approximate positions of specific residues in the open state. Arrows denote the movements of the respective residues from the C1 state to the O state. The minus sign denotes a DHA position consistent with the experimental data.
