Analysis of the deactivation time constant. (A) A two-exponential function was fitted to the deactivating K⁺-currents. The monotonically decaying phase of the deactivating currents was fitted with a double exponential function (red traces); there is a small yet unambiguous lag phase at the beginning of the deactivation currents. (B and C) The average deactivation time constants (τ_DEACT) were plotted as function of the duration of the activating pulse (t_PULSE) for oocytes expressing WT K_V7.2 (B, n = 9) and the mutant R198 (C, n = 16 for pH_EXT 6.0, n = 11 for pH_EXT 7.0, n = 8 for pH_EXT 7.4, and n = 6 for pH_EXT 8.0). Statistical test was performed using the pH_EXT 7.4 as reference. T test confidences are color-coded.