Fig. 1.

Inactivation of Kv3.4 is impeded by hemin. a Mean inside-out patch-clamp current traces, normalized to the peak current, from HEK293t cells expressing Kv3.4 channels for depolarization steps to 50 mV from a holding potential of − 100 mV in solutions containing 200 μM reduced GSH about 1 min after patch excision (Ctrl, black) and about 2 min after application of the same control solution (left) or solutions containing the indicated hemin concentration (color). Thick traces are mean values and shading indicates SEM. For n, see panel (b). b Mean non-inactivated current fraction at 50 ms after depolarization onset under control conditions (white bars) and for the indicated hemin concentrations (color). Data are means ± SEM with n in parentheses. c Alignment of the N-terminal protein sequences of (rat) rKv1.4 and rKv3.4 α subunits with Cys and His highlighted (top). Mean normalized current traces as in (a) for rKv3.4 mutants C6S, C24S and the combination C6S:C24S(SS) for application of 200 nM hemin (bottom). d Mean non-inactivated current fraction for 200 nM hemin application to the indicated mutants