Single-channel I-t traces (5 s) obtained in 1, 2, and 3 M KCl at applied potentials of −50, −80, and −120 mV (cis vs trans). When the channel transits to a closed state and does not recover to the open state, a reversal potential (+50, +80, +120 mV) is applied as indicated by the arrow. Experiments were carried out at 20.0 °C in pH 5.0 solutions. The I-t traces were post-filtered at 2 kHz for presentation.