Slc7a5 and Kvβ influence gating properties for WT Kv1.2. (A) Combinations of WT Kv1.2, Slc7a5, and Kvβ were transfected in LM mouse fibroblasts. Cells were hyperpolarized to −120 mV for 30 s before recording to disinhibit Kv1.2 currents. A 100-ms depolarization potentiating prepulse to +60 mV was delivered to relieve Kv1.2 use-dependent activation at the beginning of each sweep. G–V relationships were measured by stepping between −130 and 110 mV (150 ms in 10-mV steps, −100-mV holding potential), followed by a tail current voltage of −30 mV. Representative current traces of the activation curves are shown, with the pulse to −20 mV highlighted in green. (B) G–V plots were generated by analyzing the tail current amplitudes at −30 mV and fitting with a Boltzmann function (WT Kv1.2 V_1/2 = −6.7 ± 5 [mean ± SD], k = 10 ± 3, n = 11 individual cells recorded; Kv1.2 + Kvβ V_1/2 = −16.4 ± 4.5, k = 10.3 ± 1.8, n = 10; Kv1.2 + Slc7a5 V_1/2 = −52.5 ± 4.9, k = 9.50, n = 9; Kv1.2 + Kvβ + Slc7a5 V_1/2 = −55 ± 11, k = 10.0 ± 1.5, n = 8). (C)V_1/2 of individuals cells from each group in A. Box plots depict the median, 25th, and 75th percentiles (box) and the 10th and 90th percentiles (whiskers).