G-V curves from all AA scans of L358 and L361. (A–H) Averaged G-V curves from L358X (A–D) and L361X (E–H). For a better view, in each of the scans, mutations into charged AAs (D, E, R, H, and K) are shown in A and E, polar AAs (N, Q, S, and T) in B and F, hydrophobic AAs including aromatic amino acids (A, I, L, M, V, F, W, and Y) in C and G, and special cases AAs (C, G, and P) in D and H. For comparison, the G-V curves from WT channels is shown in all graphs. Continuous lines are the best fit of a two-state model to the data (see Materials and methods). (I) The fitted voltage V_1/2 from both scans are shown with the color code in the plot is the same as that used in Fig. 2. In all plots, vertical bars from the colored symbols representing each data point denote the SEM.