Figure 4. Mode shift in Shaker K... | Rockefeller University Press

Figure 4.

$Figure 4. Mode shift in Shaker K+ channels. (A) FV curves for the three mutants ShakerIR-A359C, ShakerIR-A359C-I384N, and ShakerIR-A359C-F484G for holding potential (HP) at −90 and 0 mV in response to a series of depolarizing pulses to a potential of −120 to 60 mV and 40 to −160 mV, respectively. Reversal potential was adjusted to 0 mV. The FVs of A359C were significantly shifted (P < 0.0001), and the uncoupled mutants were not (P ≥ 0.3). (B) Comparison of FV and QV curves of the three mutants ShakerIR-A359C-W434F, ShakerIR-A359C-W434F-I384N, and ShakerIR-A359C-W434F-F484G for holding potentials at −90 and 0 mV in response to voltage pulses of 50-ms duration to voltages ranging between −160 and 50 mV in steps of 10 mV. (C) FV of ShakerIR-A359C from a holding potential of −90 mV to a prepulse of 0 mV for variable duration (0–1,200 ms) followed by a series of pulses of 50 to −160 mV in steps of 10 mV. The FV curves were fitted to a sum of two Boltzmann curves. (right) The fraction of the FV0 Boltzmann as a function of the duration of the depolarizing prepulse is shown. (A–C) Data shown are mean ± SD.$

Mode shift in Shaker K⁺ channels. (A) FV curves for the three mutants ShakerIR-A359C, ShakerIR-A359C-I384N, and ShakerIR-A359C-F484G for holding potential (HP) at −90 and 0 mV in response to a series of depolarizing pulses to a potential of −120 to 60 mV and 40 to −160 mV, respectively. Reversal potential was adjusted to 0 mV. The FVs of A359C were significantly shifted (P < 0.0001), and the uncoupled mutants were not (P ≥ 0.3). (B) Comparison of FV and QV curves of the three mutants ShakerIR-A359C-W434F, ShakerIR-A359C-W434F-I384N, and ShakerIR-A359C-W434F-F484G for holding potentials at −90 and 0 mV in response to voltage pulses of 50-ms duration to voltages ranging between −160 and 50 mV in steps of 10 mV. (C) FV of ShakerIR-A359C from a holding potential of −90 mV to a prepulse of 0 mV for variable duration (0–1,200 ms) followed by a series of pulses of 50 to −160 mV in steps of 10 mV. The FV curves were fitted to a sum of two Boltzmann curves. (right) The fraction of the FV₀ Boltzmann as a function of the duration of the depolarizing prepulse is shown. (A–C) Data shown are mean ± SD.