Figure 4. Inactivation of the ternary Kv4.1 channel complex traps internally applied bTBuA.

The ternary Kv4.1 channel complex was heterologously expressed in Xenopus oocytes as explained under Methods. This complex includes the accessory subunits KChIP-1 and DPP6. (a) Inside-out macropatch outward currents evoked as described in Figs 2 and 3 legend. (b) Magnitude of peak currents in five consecutive iterations of the pulse protocol. Additional details as described in Fig. 3 legend. (c) Scaled and normalized currents from panel (a). (d) Time constants of decay from the currents evoked by the test pulses as explained in Fig. 3 legend. The reported time constant is the weighted average of the double exponential best-fit time constants. (e) Box plots of the time constants of current decay during blockade by bTBuA (blue box), after washout (green box) and from the currents evoked by P8 (N = 5 patches; 5–40 iterations each). (f) Box plots of the peak current amplitudes during blockade by bTBuA (blue box), after washout (green box) and from the currents evoked by P8 (N = 5 patches; 5–40 iterations each). On average, the peaks of currents evoked by P3 and P8 are significantly different (Kruskal-Wallis, p < 1.3 × 10⁻¹¹).