2-D joint plots of salt-bridge distances in the VSD. Minimum distances between two residues in the VSD. Distances were measured from the center of geometry of carboxyl oxygen atoms in glutamic/aspartic acid and the terminal −NH₂ atoms in the guanidino group. See http://github.com/bigginlab/nav-alt-splice for full atom selections. (A–C) Minimum distances between E208/R222 and E208/R219 for hNav1.5-T207S, hNav1.5-D211K, and hNav1.5-T207S-D211K, respectively. (D–F) Minimum distances between D152/R222 and D152/R219 for hNav1.5-T207S, hNav1.5-D211K, and hNav1.5-T207S-D211K, respectively. (G–I) Minimum distances between E161/R225 and E161/R222 for hNav1.5-T207S, hNav1.5-D211K, and hNav1.5-T207S-D211K, respectively.