(A) Representative whole-cell current traces at physiological extracellular pH 7.4 recorded from oocytes injected with equivalent amounts of mRNA for either WT TASK-2 or the T108P variant. Currents were recorded using 300 ms voltage steps from a holding potential of -80 mV delivered in 20 mV increments between -140 mV and +100 mV. (B) Similar currents recorded after extracellular. (C) Activation of WT TASK-2 currents at alkaline pH. Results shown as means ± s.e.m. (D) Averaged whole-cell currents from uninjected control oocytes and cells expressing either WT or T108P TASK-2 channels at the indicated external pH values (WT vs T108P, P<0.01 at pH 7.4 and pH 9, one-way ANOVA, post-hoc Tukey HSD test; n = 9 for all conditions).

https://doi.org/10.1371/journal.pone.0160114.g001

Confocal microscopy of GFP-tagged WT and mutant TASK-2 channels. (A) WT TASK-2 and T108P tagged with GFP at the C-termini expressed in oocytes. The red fluorescent signal (Wheat Germ Agglutinin CF633) indicates the location of the cell membrane. WT channels tagged with GFP (green) exhibit a clear membrane-associated fluorescence, whereas the mutant T108P channels showed no membrane localization, and no GFP fluorescence in any other part of the oocyte. (B) Representative relative signal-intensity profiles for oocytes expressing WT or T108P mutant channels. Intensities were determined along the cross-sections indicated by the red lines in panel A.

https://doi.org/10.1371/journal.pone.0160114.g002