145D/E polymorphism does not alter the KCNE4-dependent acceleration of slow inactivation of Kv1.3. (A) Representative 5-s-long traces at +60 mV of HEK293 cells transfected with Kv1.3 without or with KCNE4 (+145D, +145E, +145A). (B) Normalization of representative currents in A to visualize the slow inactivation of the channel. (C) 5-s traces were fitted with a monoexponential equation to calculate the τ_inactivation. The values represent the mean ± SE of 5–19 cells for each condition from four different transfections, as depicted. Statistical analysis: one-way ANOVA (P < 0.026) with Tukey’s multiple comparisons test. Specific P values were as follows: *P < 0.05 (0.0344 vs. +145D; 0.0371 vs. +145E; 0.0229 vs. +145A). (D) Representative currents of a train of 15 depolarizing pulses at a frequency of 2.5 Hz at +60 mV. (E) Relativized peak current for each of the 15 pulses from the protocol in D. (F) Current decay from E was fitted to a monoexponential decay to calculate the decay constant. The values represent the mean ± SE of 5–9 cells for each condition, as depicted. In each experiment, two different random conditions—always including Kv1.3 alone—from four different transfections, were recorded. Statistical analysis: one-way ANOVA (P < 0.0108) with Tukey’s multiple comparisons test. Specific P values were as follows: *P < 0.05 (0.0305 vs. +145D; 0.0130 vs. +145E; 0.0188 vs. +145A). Black circles, Kv1.3 alone; blue squares, +145D; orange triangles, +145E; and green diamonds, +145A.