Run-up may involve activation of Leu-sensitive proteases. (A) Mean data from 10 recordings with 5 mM MgATP and 100 µM Leu (ATP+Leu), 9 recordings with 100 µM Leu only (Leu), and 17 parallel control recordings (Ctrl). (B) Same data as in A but normalized to the initial current amplitude to illustrate differences in the magnitude of run-up. (C) Comparison of the current increase during run-up with ATP+Leu, Leu only, and in parallel control recordings (same cells as in A). (D) Comparison of the run-up duration with ATP+Leu, Leu only, and in parallel control recordings (same cells as in A). (E) Time course of changes in inactivation during the 30-ms test pulses with ATP+Leu, Leu only, and in parallel control recordings (same cells as in A). **, P < 0.01 (one-way ANOVA with Bonferroni post hoc correction in D or Welch’s ANOVA with the Games-Howell multiple-comparison method in C). Values are expressed as mean ± SEM.