Modification of E290C by MTSES restored its sensitivity to K⁺_e. (A) Current traces recorded in 4 mM K⁺_e before (left) and after (middle) MTSES modification. The right panel shows the current traces after perfusion by 50 mM K⁺_e after MTSES modification. (B) The comparison of the K⁺_e sensitivities of WT, E290C, and MTSES-modified E290C. Note that after modification by MTSES, data obtained from E290C (●, n = 5) were approaching the WT values (□).