| First Author | Sulaiman P | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 10 | Pages | 7420-9 |
| PubMed ID | 23339194 | Mgi Jnum | J:203518 |
| Mgi Id | MGI:5527145 | Doi | 10.1074/jbc.M112.412791 |
| Citation | Sulaiman P, et al. (2013) Kir2.4 surface expression and basal current are affected by heterotrimeric G-proteins. J Biol Chem 288(10):7420-9 |
| abstractText | 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 Galphao1. Here, we wished to determine whether and how Galphao affects this channel. Using transfected HEK 293 cells and retinal tissue, we showed that Kir2.4 interacts with Galphao, and this interaction is stronger with the GDP-bound form of Galphao. 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 Galphao reduce the Kir2.4 basal current, whereas the active mutant has little effect. Other pertussis-sensitive Galpha subunits also reduce this current, whereas Galphas increases it. Gbetagamma increases the current, whereas m-phosducin, which binds Gbetagamma without affecting the state of Galpha, 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 Gbeta3, localization of Kir2.4 in the dendritic tips is reduced. We conclude that Gbetagamma targets Kir2.4 to the plasma membrane, and Galphao slows this down by binding Gbetagamma. |
