GV curves and deactivation kinetics for WT, IQM, and CW. (A) Structure of hNav1.4 (PDB accession no. 6AGF) and the locations of the IQM mutation (F1304Q) and the CW mutation (L437C_A438W). (B–D) Example ionic current traces for WT, IQM, and CW, respectively. Both IQM and CW can remove most of the fast inactivation. The inset shows the voltage protocol. (E) GV curves for WT, IQM, and CW. All three constructs share similar GV curves. N = 6 for all constructs. Data plotted as Mean ± SEM. (F) Tail-current (deactivation) kinetics of WT, IQM, and CW after 2, 10, and 10 ms depolarization, respectively. The tail current was normalized to the peak. While WT and IQM share similar deactivation kinetics, CW has significantly slower channel closure. The inset shows the voltage protocol. (G) Fitted time constants for tail current were obtained after 2 ms depolarization for WT and 30 ms depolarization for IQM and CW. N = 6 for WT and IQM; N = 7 for CW. Data plotted as Mean ± SEM in log scale.