Cooperative regulation by G proteins and Na(+) of neuronal GIRK2 K(+) channels

Elife. 2016 Apr 13:5:e15751. doi: 10.7554/eLife.15751.

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.

Keywords: G protein; G protein gated potassium channel; Ni-NTA lipid; biochemistry; biophysics; dopaminergic neuron; mouse; planar lipid bilayer; sodium activation; structural biology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Biological Assay
  • Dopaminergic Neurons / cytology
  • Dopaminergic Neurons / metabolism*
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels / genetics
  • G Protein-Coupled Inwardly-Rectifying Potassium Channels / metabolism*
  • GTP-Binding Protein beta Subunits / genetics
  • GTP-Binding Protein beta Subunits / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • Gene Expression Regulation
  • Humans
  • Mice
  • Pars Compacta / cytology
  • Pars Compacta / metabolism
  • Patch-Clamp Techniques
  • Phosphatidylethanolamines / chemistry
  • Phosphatidylethanolamines / metabolism
  • Phosphatidylglycerols / chemistry
  • Phosphatidylglycerols / metabolism
  • Pichia / genetics
  • Pichia / metabolism
  • Primary Cell Culture
  • Protein Multimerization
  • Protein Subunits / genetics
  • Protein Subunits / metabolism*
  • Proteolipids / chemistry
  • Proteolipids / metabolism
  • Receptors, GABA-B / genetics
  • Receptors, GABA-B / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction
  • Sodium / metabolism

Substances

  • G Protein-Coupled Inwardly-Rectifying Potassium Channels
  • GNB1 protein, human
  • GNG2 protein, human
  • GTP-Binding Protein beta Subunits
  • Kcnj6 protein, mouse
  • Phosphatidylethanolamines
  • Phosphatidylglycerols
  • Protein Subunits
  • Proteolipids
  • Receptors, GABA-B
  • Recombinant Proteins
  • proteoliposomes
  • 1-palmitoyl-2-oleoylphosphatidylethanolamine
  • 1-palmitoyl-2-oleoylglycero-3-phosphoglycerol
  • Sodium
  • GTP-Binding Proteins