Fig. 4. Rescue effects of KCNQ openers on KCNQ4 mutant channels assembled from tandem concatemers.

a Total K⁺ currents were measured in the absence (-PIP5K) or presence (+PIP5K) of PIP5K expression in HEK293T cells, and responses to KCNQ openers were recorded. Representative current traces recorded before (Ctrl) and after 10 μM ZnPy treatment are presented for each concatemer channel. b Rescue effects of KCNQ openers (10 μM Ret, 10 μM ZnPy, and 3 μM ML213) on KCNQ4 mutant channels assembled from homomeric settings or heteromeric tandem concatemers were compared in the absence or presence of PIP5K expression. Current densities measured at +40 mV were compared as bar graphs. c Half-activation voltages (V_0.5) were calculated from activation curves, and the values are plotted as bars. Horizontal dotted lines in the graphs indicate the current density level b or V_0.5 values c of the control homomeric WT channels (WT, Ctrl) measured in the absence of PIP5K and KCNQ openers. The names of the groups are indicated in insets on the graph. Mean ± SEM. n = 10–12.