XB-IMG-150383
Xenbase Image ID: 150383
|
|
Fig 6. Dose-dependent activation of GIRK1/2 by coexpressed Gβγ: experiment and simulation.GIRK1/2 was expressed at 0.2 ng RNA. All data are mean ± SEM from one experiment. (A) Confocal images of Gβγ in giant excised plasma membranes stained with the anti-Gβ antibody. The intensity of all images was increased equally for a better viewing in this figure, but not in the process of image analysis. (B) Dose-dependence of Gβγ levels and Iβγ in oocytes injected with incrementing amounts of wt Gβγ RNA (0.05–30 ng per oocyte). Gβγ expression in the PM (grey bars) was measured from images shown in A, in 4–8 oocyte membranes, and Iβγ currents (red circles; right Y-axis) were measured in 12–16 oocytes. The dashed line shows the basal level of fluorescence, arising from the endogenous Gβγ. Note that, unlike in Western blots, in immunocytochemistry the antibody poorly recognized the endogenous Gβγ compared to the expressed bovine Gβγ. (C) Comparison of measured Iβγ and Rβγ (red circles) and simulated currents (curves). The relative Gβγ levels (from grey bars in B) have been converted into surface densities assuming that 5 ng Gβγ gives 30 molecules Gβγ/μm2. The blue line presents the simulation using graded contribution model and amounts of Gα and Gβγ (prior to coexpression of Gβγ) calculated using the methods described above: channel density was calculated from Iβγ (13.75 channels/μm2 with 5 ng Gβγ RNA in this experiment), and Gβγ and Gα were estimated from Itotal and Ibasal, giving 3.16 and 0.73 Gβγ:GIRK and Gα:GIRK ratios, respectively. For simulation with endogenous G proteins only and no Gβγ recruitment allowed (red, black and green lines), the channel density was the same and 1, 10 or 24 endogenous Gαβγ were assumed to be available for GIRK1/2. Image published in: Yakubovich D et al. (2015) Image reproduced on Xenbase with permission of the publisher and the copyright holder. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View |