Figure 3.
Kvβ stabilizes Kv1.2 in an Slc7a5-induced nonconducting state. Combinations (as indicated in Fig. 1 A) of WT Kv1.2, Slc7a5, and Kvβ or KvβΔN were transfected in LM cells. Currents were measured at +10 mV (50-ms pulses, every 2 s). (A) Exemplar patch clamp records of WT Kv1.2 and Kv1.2 + Slc7a5 measured continuously at +10 mV (50 ms pulses, every 2 s) from a −120-mV holding voltage. Sample currents on the right depict the peak current amplitude at the first (black) and last (green) pulse following a train of depolarizations from a holding potential of −120 mV. (B) Cell-by-cell current density (at +10 mV) of the first pulse (black) and final (green) pulse following a train of depolarizations from a −120-mV holding potential for 30 s (n = 11 individual cells recorded for WT Kv1.2, n = 9 for Kv1.2 + Kvβ, n = 8 for Kv1.2 + KvβΔN, n = 16 for Kv1.2 + Slc7a5, n = 12 for Kv1.2 + Kvβ + Slc7a5, n = 20 for Kv1.2 + KvβΔN + Slc7a5). (C) Bar graph depicting the mean (± SEM) fold change of disinhibition between the first and final test pulses of a 30-s pulse from a −120-mV holding voltage (n = 11 for WT Kv1.2, n = 9 for Kv1.2 + Kvβ, n = 8 for Kv1.2 + KvβΔN, n = 16 for Kv1.2 + Slc7a5, n = 12 for Kv1.2 + Kvβ + Slc7a5, n = 20 for Kv1.2 + KvβΔN + Slc7a5). Student’s t test was used to compare the fold change of disinhibition of Kv1.2 + Kvβ + Slc7a5 versus Kv1.2 + Slc7a5 and Kv1.2 + KvβΔN + Slc7a5 versus Kv1.2 + Slc7a5. P values are denoted above the bars. (D) Representative traces of the current amplitude following a train of depolarizations from a 30-s holding voltage at −120 mV then an additional 15-s holding voltage at −160 mV. (E) Bar graph depicting the mean (± SEM) fold change of disinhibition between the first and final test pulses of a 15-s pulse from a −160-mV holding voltage after cells had undergone a 30-s −120-mV train (n = 6 for Kv1.2 + Slc7a5, n = 8 for Kv1.2 + Kvβ + Slc7a5, n = 15 for Kv1.2 + KvβΔN + Slc7a5). Student’s t test was used to compare the fold change of disinhibition of Kv1.2 + Kvβ + Slc7a5 versus Kv1.2 + Slc7a5 and Kv1.2 + KvβΔN + Slc7a5 versus Kv1.2 + Slc7a5. P values are denoted above the bars.

Kvβ stabilizes Kv1.2 in an Slc7a5-induced nonconducting state. Combinations (as indicated in Fig. 1 A) of WT Kv1.2, Slc7a5, and Kvβ or KvβΔN were transfected in LM cells. Currents were measured at +10 mV (50-ms pulses, every 2 s). (A) Exemplar patch clamp records of WT Kv1.2 and Kv1.2 + Slc7a5 measured continuously at +10 mV (50 ms pulses, every 2 s) from a −120-mV holding voltage. Sample currents on the right depict the peak current amplitude at the first (black) and last (green) pulse following a train of depolarizations from a holding potential of −120 mV. (B) Cell-by-cell current density (at +10 mV) of the first pulse (black) and final (green) pulse following a train of depolarizations from a −120-mV holding potential for 30 s (n = 11 individual cells recorded for WT Kv1.2, n = 9 for Kv1.2 + Kvβ, n = 8 for Kv1.2 + KvβΔN, n = 16 for Kv1.2 + Slc7a5, n = 12 for Kv1.2 + Kvβ + Slc7a5, n = 20 for Kv1.2 + KvβΔN + Slc7a5). (C) Bar graph depicting the mean (± SEM) fold change of disinhibition between the first and final test pulses of a 30-s pulse from a −120-mV holding voltage (n = 11 for WT Kv1.2, n = 9 for Kv1.2 + Kvβ, n = 8 for Kv1.2 + KvβΔN, n = 16 for Kv1.2 + Slc7a5, n = 12 for Kv1.2 + Kvβ + Slc7a5, n = 20 for Kv1.2 + KvβΔN + Slc7a5). Student’s t test was used to compare the fold change of disinhibition of Kv1.2 + Kvβ + Slc7a5 versus Kv1.2 + Slc7a5 and Kv1.2 + KvβΔN + Slc7a5 versus Kv1.2 + Slc7a5. P values are denoted above the bars. (D) Representative traces of the current amplitude following a train of depolarizations from a 30-s holding voltage at −120 mV then an additional 15-s holding voltage at −160 mV. (E) Bar graph depicting the mean (± SEM) fold change of disinhibition between the first and final test pulses of a 15-s pulse from a −160-mV holding voltage after cells had undergone a 30-s −120-mV train (n = 6 for Kv1.2 + Slc7a5, n = 8 for Kv1.2 + Kvβ + Slc7a5, n = 15 for Kv1.2 + KvβΔN + Slc7a5). Student’s t test was used to compare the fold change of disinhibition of Kv1.2 + Kvβ + Slc7a5 versus Kv1.2 + Slc7a5 and Kv1.2 + KvβΔN + Slc7a5 versus Kv1.2 + Slc7a5. P values are denoted above the bars.

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