Figure 2. In the absence of KCNE1, S140G slowing of voltage sensor deactivation is independent of channel opening based on PIP₂ depletion.

The following protocol was used: from a prepulse of −140 mV, an activating pulse was applied at +40 mV, followed by a repolarizing step to −100 mV. Channels were held at −80 mV. This protocol was used before and after PIP₂ depletion by ciVSP, which was activated by repeated depolarization. (a,b) Current before (+PIP₂) and after PIP₂ depletion (−PIP₂) for KCNQ1 (a) and KCNQ1^S140G (b). (c,d) Normalized fluorescence deactivation traces at −100 mV for KCNQ1 (red) and KCNQ1^S140G (dark red) before (c) and after (d) PIP₂ depletion. (e) Time to half deactivation (t_1/2) of fluorescence. Data are shown as mean ± SEM (error bars). *P < 0.05.