Slc7a5 shifts the voltage dependence of activation of Kv1.2- and Kvβ-regulated Kv1.2 channels. (A) Combinations (as indicated in Fig. 1 A) of Kv1.2[T252R], Slc7a5, and Kvβ were transfected in LM cells. Cells were hyperpolarized to −120 mV for 30 s before recording to disinhibit Kv1.2 currents. 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 with the pulse to −20 mV are highlighted in green. (B) G–V plots were generated by analyzing the tail current amplitudes at −30 mV and fitting with a Boltzmann function (Kv1.2[T252R] V_1/2 = −16.9 ± 3.9 [mean ± SD], k = 8.3 ± 1.9, n = 8 individual cells recorded; Kv1.2[T252R] + Kvβ V_1/2 = −23.6 ± 4.2, k = 7.5 ± 1.3 n = 11; Kv1.2[T252R] + Slc7a5 V_1/2 = −54 ± 4, k = 8.6 ± 1.7, n = 10; Kv1.2[T252R] + Kvβ + Slc7a5 V_1/2 = −54 ± 14, k = 11.7 ± 1.8, n = 8). (C)V_1/2 of individual cells from each group in A and B are summarized and displayed as box plots for comparison. Box plots depict the median, 25th, and 75th percentiles (box) and the 10th and 90th percentiles (whiskers).