Fig. 3.

Reduced regulation of deactivation gating by soluble eag domains containing point mutations. Two-electrode voltage-clamp recordings of ionic current from (A) N1–135 (Y43A) CFP fragment + hERG ΔN YFP channels (inverted, closed triangle) and (B) N1–135 (R56Q) CFP fragment + hERG ΔN YFP channels (closed triangle). Calibration bar is 2 μA and 250 ms. (C) Plot of time constant (τ) of deactivation versus voltage. Time constants for N1–135 CFP + hERG ΔN YFP (closed circles) and hERG ΔN YFP (open squares) included for comparison. Error bars are the SEM and the n ≥ 3 for each point. (D) Bar graph of relative FRET efficiency (Ratio A − Ratio A₀) and ratio of CFP to YFP (Fc/Fy) for the indicated channels. SEM is denoted by error bars; the number of experiments (n) is indicated in parentheses.