TY - JOUR TI - Quantitative analysis of mammalian GIRK2 channel regulation by G proteins, the signaling lipid PIP2 and Na+ in a reconstituted system AU - Wang, Weiwei AU - Whorton, Matthew R AU - MacKinnon, Roderick A2 - Aldrich, Richard VL - 3 PY - 2014 DA - 2014/07/20 SP - e03671 C1 - eLife 2014;3:e03671 DO - 10.7554/eLife.03671 UR - https://doi.org/10.7554/eLife.03671 AB - GIRK channels control spike frequency in atrial pacemaker cells and inhibitory potentials in neurons. By directly responding to G proteins, PIP2 and Na+, GIRK is under the control of multiple signaling pathways. In this study, the mammalian GIRK2 channel has been purified and reconstituted in planar lipid membranes and effects of Gα, Gβγ, PIP2 and Na+ analyzed. Gβγ and PIP2 must be present simultaneously to activate GIRK2. Na+ is not essential but modulates the effect of Gβγ and PIP2 over physiological concentrations. Gαi1(GTPγS) has no effect, whereas Gαi1(GDP) closes the channel through removal of Gβγ. In the presence of Gβγ, GIRK2 opens as a function of PIP2 mole fraction with Hill coefficient 2.5 and an affinity that poises GIRK2 to respond to natural variations of PIP2 concentration. The dual requirement for Gβγ and PIP2 can help to explain why GIRK2 is activated by Gi/o, but not Gq coupled GPCRs. KW - G protein gated potassium channel KW - planar lipid bilayer KW - G protein KW - PIP2 KW - sodium activation KW - G protein coupled receptor JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -