title: Cooperative regulation by G proteins and Na(+) of neuronal GIRK2 K(+) channels.
abstract: G protein gated inward rectifier K(+) (GIRK) channels open and thereby silence cellular electrical activity when inhibitory G protein coupled receptors (GPCRs) are stimulated. Here we describe an assay to measure neuronal GIRK2 activity as a function of membrane-anchored G protein concentration. Using this assay we show that four Gβγ subunits bind cooperatively to open GIRK2, and that intracellular Na(+) - which enters neurons during action potentials - further amplifies opening mostly by increasing Gβγ affinity. A Na(+) amplification function is characterized and used to estimate the concentration of Gβγ subunits that appear in the membrane of mouse dopamine neurons when GABAB receptors are stimulated. We conclude that GIRK2, through its dual responsiveness to Gβγ and Na(+), mediates a form of neuronal inhibition that is amplifiable in the setting of excess electrical activity.
authors.affiliation: Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, Rockefeller University, New York, United States.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, Rockefeller University, New York, United States.
authors.forename: Kouki K
authors.initials: KK
authors.lastname: Touhara
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, United States.
authors.forename: Keiko
authors.initials: K
authors.lastname: Weir
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, United States.
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Bean
authors.affiliation: Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, Rockefeller University, New York, United States.
authors.forename: Roderick
authors.identifier: 0000-0001-7605-4679
authors.initials: R
authors.lastname: MacKinnon
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001681:Biological Assay; D059290:Dopaminergic Neurons / Q000166:cytology / Q000378:metabolism*; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D065842:Pars Compacta / Q000166:cytology / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D055503:Protein Multimerization; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D011510:Proteolipids / Q000737:chemistry / Q000378:metabolism; D018080:Receptors, GABA-B / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C516790:GNB1 protein, human; C410342:GNG2 protein, human; D044387:GTP-Binding Protein beta Subunits; C497069:Kcnj6 protein, mouse; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D021122:Protein Subunits; D011510:Proteolipids; D018080:Receptors, GABA-B; D011994:Recombinant Proteins; C020485:proteoliposomes; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; D012964:Sodium; D019204:GTP-Binding Proteins
keywords: G protein; G protein gated potassium channel; Ni-NTA lipid; biochemistry; biophysics; dopaminergic neuron; mouse; planar lipid bilayer; sodium activation; structural biology