Fig. 3: Verification of ion species and key residues in coordination.

a MD simulation estimating the ion species and binding stability in I1 and I2 sites indicates that while both Cl⁻ and I⁻ are stable in I1 site, I2 site is more stable for I⁻ binding and instable for Cl⁻. In each panel, the six different colored lines represent the distance between ion and each site in the dimer system across different replicate simulations. The simulations consisted of three independent 100 ns replicates, with snapshots of the system saved every 100 ps for analysis. b The Cl⁻ current and I⁻ current (at +100 mV) of WT, control and mutants were shown respectively. The number of cells patched for each group (in the order of WT, Control, F104A, F104E, F104K, H189A, H189E) were n = 17, 14, 14, 9, 19, 16, 11 (Cl⁻ current) and n = 29, 26, 20, 12, 16, 13, 27 (I⁻ current). Data represent the means ± SEM, *P < 0.1, **P < 0.01, ***P < 0.001, ****P < 0.0001 (The significance is calculated by one-way ANOVA with uncorrected Fisher’s LSD test. The exact P values for Cl⁻ currents measurements are: WT vs. Control: 0.0132, WT vs. F104A: 0.0005, WT vs. F104E: 0.0721, WT vs. F104K: <0.0001, WT vs. H189A: 0.0355, WT vs. H189E: 0.0679. The exact P values for I⁻ currents measurements are: WT vs. Control: <0.0001, WT vs. F104A: 0.0019, WT vs. F104E: 0.0400, WT vs. F104K: <0.0001, WT vs. H189A: 0.0030, WT vs. H189E: 0.0004).