The S-shaped kinetics of LF_N translocation through the (PA₆₃)₇ channel. After the (PA₆₃)₇-induced conductance had reached a more or less steady state, LF_N (with the N-terminal His₆ tag removed) was added (at the arrow) to the cis-side to a concentration of 6 nM, resulting in a rapid fall in conductance. LF_N (along with (PA₆₃)₇) was then perfused out of the cis-compartment (during the ∼4-min break in the record); the conductance increased only slightly over this time. When the voltage was stepped from 20 to 45 mV, there was an S-shaped rise of conductance to a value comparable with that before the addition of LF_N, and it remained at that value when the voltage was stepped back from 45 to 20 mV. The rate of conductance rise directly reflects the rate of translocation of LF_N; i.e., the rate of its traversing the channel and exiting into the trans-solution. This figure was adapted from Fig. 2 of Finkelstein (2009).