Slc7a5 significantly prolongs recovery from Kvβ-induced inactivation. LM cells expressing Kv1.2[T252R] + Kvβ or Kv1.2[T252R] + Kvβ + Slc7a5 were subjected to 500-ms inactivating pulses to +100 mV followed by repolarizing pulses to −100 mV for 5-, 10-, or 50-ms intervals up to 600 ms. Cells were hyperpolarized to −120 mV for 30 s before recording to disinhibit Kv1.2 currents. (A) Representative current traces of channel recovery from inactivation at repolarizing pulses to −100 mV for 10 and/or 50 ms. (B) Recovery of the channels from inactivation was measured during 30-ms test pulses to +100 mV, after a −100-mV recovery potential for 5–600 ms. Current amplitude was analyzed at each +100-mV test pulse, following the allotted time at −100 mV (data shown as mean ± SEM, n = 14–16 individual cells recorded for each group). (C) Recovery from inactivation was measured during 30-ms test pulses to +100 mV, after a −120 mV recovery potential for 5–600 ms. Current amplitude was analyzed at each +100-mV test pulse, following the allotted time at −120 mV (data shown as mean ± SEM).