Fig. 7.

Ligands that induce conformational rearrangements at the biosensors monitoring Gβγ interaction with channel subunits also induce whole-cell currents. HEK293 cells transfected with the Kir3.1-Luc/Gγ2-YFP pair DOR and Kir3.2 were studied using whole-cell patch-clamp voltage clamped at 100 mV. (A) The presence of a basal current was determined by incubating cells in a high K⁺ solution (140 mM). Addition of the agonist DPDPE (1 µM) evoked a current that returned to basal values on removal of the agonist. Preincubation with the antagonist naltrindole (1 µM) blocked currents induced by DPDPE. (B) Individual traces of whole-cell currents induced by different agonists. DPDPE was used to determine functional channel current in each cell, and traces for all agonists were normalized to the maximum current produced by DPDPE. (C) Agonist-evoked whole-cell currents (1 µM) were normalized to DPDPE, and results are expressed as percent of maximal response induced by this agonist. Values represent mean ± S.E.M. of three experiments. Statistical comparisons were done by one-way analysis of variance, followed by Bonferroni posthoc test for multiple comparisons.