A survival plot of the number of channels that are still blocked by His₆-LF_N (that is, His₆-LF_N has not yet translocated through them) as a function of time (Δt) after the voltage was stepped from 20 to 48 mV. A representative single-channel record from which the plot was generated is shown in the inset. (In this single-channel record, the voltage was stepped to 50 instead of to 48 mV.) With the voltage held at 20 mV, an open channel became blocked by His₆-LF_N (present in the cis-solution) at the first asterisk. After 5 s, the voltage was stepped to 50 mV, and after time Δt, the channel became unblocked. The voltage was then stepped back to 20 mV. After ∼25 s, the channel became blocked again, and the voltage was stepped to 50 mV, etc. The arrowheads mark the current level of the closed channel (c), the open channel at 20 mV (O₂₀), and the open channel at 50 mV (O₅₀).