Mode shift is removed in uncoupled mutants I384N and F484G. (A) Gating and ionic currents in response to a series of depolarizing pulses from a holding potential of V_hold = −90 mV to a potential of −120 to 180 mV in steps of 10 mV elicited from ShakerIR-I384N. Both gating and ionic currents are detectable. (B) Time constants from exponential fits of the gating currents (saturating depolarizations) obtained from W434F (n = 7), W434F-I384N (n = 6), and W434F-F484G (n = 4). (C) QV curves were elicited for holding potentials at −90 (QV₉₀) and at 0 mV (QV₀) of ShakerIR-W434F, ShakerIR-W434F-I384N, and ShakerIR-W434F-F484G in response to a series of depolarizing pulses from −160 to 60 mV in steps of 10 mV. No shift of the QVs is observed in the uncoupled mutants (P > 0.3) except for W434F (P < 0.0001). (D) QV relations of ShakerIR-W434F in response to a series of pulses from a given holding potential (HP) to variable voltages. (right) V_1/2 of single Boltzmann fits as a function of the holding potential of the data on left. The shift occurs at voltages between −60 and −40 mV. (B–D) Data are shown as mean ± SD.