Fig. 6. Quadruple alanine mutation of the identified residues in DIII & DIV S6 enhanced the phenotype seen in DIIIAA and DIVAA.

A Sequence alignment of DIII, DIV S6 showing identified residues (highlighted in red) and their positions in the Nav1.7 structure. B Representative current traces elicited at different voltages (−10 to 40 mV) for the quadruple alanine mutation (I1284A_I1288A_I1587A_L1591A, DIII_IVAA) in 57.5 mM external Na⁺ and 120 mM internal K⁺. C I–V curves for the peak (red, N = 4) and steady state (blue, N = 4) current. The reversal potential for each component is denoted with a corresponding dashed line. D h—infinity curve for DIII_IVAA (green), DIIIAA (red), and DIVAA (blue). E Relative Na⁺/K⁺ permeability vs. time for DIII_IVAA (57.5 mM Na⁺ external and 120 mM K⁺ internal). Dashed gray, blue, and red lines show the WT, DIIIIAA and DIVAA permeability, respectively. The solid green line represents an exponential fit to obtain the time constant. Data are shown as mean ± SEM.