A, recovery from inactivation current traces. Pulse protocol consisted of a 1 s pulse to +60 mV followed by a pulse to −30 mV. B, time constants of recovery plotted versus test voltage for WT HERG, C-terminal deletion mutants HERGCΔ236 and HERGCΔ278, and N-terminal deletion mutants HERGNΔ12 and HERGNΔ354. Symbols are indicated in the figure (n = 24, P = 0). C, recovery plots for HERGNΔ354CΔ236, HERGNΔ354CΔ278, HERGCΔ236, HERGCΔ278 and HERGNΔ354 (n = 24, P = 0). All deletion mutants had significantly faster recovery than WT channels.