Kir2.4 surface expression and basal current are affected by heterotrimeric G-proteins

J Biol Chem. 2013 Mar 8;288(10):7420-9. doi: 10.1074/jbc.M112.412791. Epub 2013 Jan 21.


Kir2.4, a strongly rectifying potassium channel that is localized to neurons and is especially abundant in retina, was fished with yeast two-hybrid screen using a constitutively active Gαo1. Here, we wished to determine whether and how Gαo affects this channel. Using transfected HEK 293 cells and retinal tissue, we showed that Kir2.4 interacts with Gαo, and this interaction is stronger with the GDP-bound form of Gαo. Using two-electrode voltage clamp, we recorded from oocytes that were injected with Kir2.4 mRNA and a combination of G-protein subunit mRNAs. We found that the wild type and the inactive mutant of Gαo reduce the Kir2.4 basal current, whereas the active mutant has little effect. Other pertussis-sensitive Gα subunits also reduce this current, whereas Gαs increases it. Gβγ increases the current, whereas m-phosducin, which binds Gβγ without affecting the state of Gα, reduces it. We then tested the effect of G-protein subunits on the surface expression of the channel fused to cerulean by imaging the plasma membranes of the oocytes. We found that the surface expression is affected, with effects paralleling those seen with the basal current. This suggests that the observed effects on the current are mainly indirect and are due to surface expression. Similar results were obtained in transfected HEK cells. Moreover, we show that in retinal ON bipolar cells lacking Gβ3, localization of Kir2.4 in the dendritic tips is reduced. We conclude that Gβγ targets Kir2.4 to the plasma membrane, and Gαo slows this down by binding Gβγ.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Membrane / metabolism*
  • Female
  • GTP-Binding Protein alpha Subunits, Gi-Go / genetics
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
  • GTP-Binding Protein beta Subunits / genetics
  • GTP-Binding Protein beta Subunits / metabolism
  • GTP-Binding Protein gamma Subunits / genetics
  • GTP-Binding Protein gamma Subunits / metabolism
  • HEK293 Cells
  • Heterotrimeric GTP-Binding Proteins / genetics
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Humans
  • Ion Channel Gating / genetics
  • Ion Channel Gating / physiology*
  • Membrane Potentials / physiology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation
  • Oocytes / metabolism
  • Oocytes / physiology
  • Patch-Clamp Techniques
  • Potassium Channels, Inwardly Rectifying / genetics
  • Potassium Channels, Inwardly Rectifying / metabolism*
  • Protein Binding
  • Retina / metabolism
  • Two-Hybrid System Techniques
  • Xenopus


  • GTP-Binding Protein beta Subunits
  • GTP-Binding Protein gamma Subunits
  • Kir2.4 channel
  • Potassium Channels, Inwardly Rectifying
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • Heterotrimeric GTP-Binding Proteins