Supplementary Figure 4: Fluorescence changes of 175C* channels track Hv1 gating transition.
From: A specialized molecular motion opens the Hv1 voltage-gated proton channel
(a-c) Fluorescence changes of 175C* are not due to proton flux. (a) Cartoon depicting N264C I175C* channels modified by intracellular MTSET. (b) Current (I) and fluorescence (F) traces of N264C 175C* in response to a voltage step from −95 to +80 mV, before application (grey) and at the end (black) of the application of 1 mM MTSET. (c) Ratio of steady-state fluorescence and current amplitudes before and after modification by MTSET measured at arrowheads in (b) (p < 0.001, two-tailed Student’s t-test; n = 6 patches). (d-f) S1 fluorescence signal tracks opening and closing kinetics in gating mutant. (d) Normalized VCF current and fluorescence traces of 175C* (grey) and D1E 175C* (black) for a depolarizing step from −80 mV to +100 mV. (e,f) Left, superposition of normalized current (black) and fluorescence (red) traces of D1E 175C* upon depolarization to +100 mV (activation) (e) and back to −80 mV (deactivation) (f). Right, average fast and slow time constants (activation) (e) and decay times (deactivation) (f) of current and fluorescence changes for 175C* (n = 16 and 13 oocytes, respectively) and D1E 175C* (n = 7 oocytes).
