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Quantitative analysis of mammalian GIRK2 channel regulation by G proteins, the signaling lipid PIP2 and Na+ in a reconstituted system.

ABSTRACT: 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 G?, G??, PIP2 and Na(+) analyzed. G?? and PIP2 must be present simultaneously to activate GIRK2. Na(+) is not essential but modulates the effect of G?? and PIP2 over physiological concentrations. G?i1(GTP?S) has no effect, whereas G?i1(GDP) closes the channel through removal of G??. In the presence of G??, 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 G?? and PIP2 can help to explain why GIRK2 is activated by Gi/o, but not Gq coupled GPCRs.

SUBMITTER: Wang W

PROVIDER: S-EPMC4135351 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Quantitative analysis of mammalian GIRK2 channel regulation by G proteins, the signaling lipid PIP2 and Na+ in a reconstituted system.

Wang Weiwei W Whorton Matthew R MR MacKinnon Roderick R

eLife 20140720

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 ...[more]

PMID: 25049222

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