Additional file 3: Figure S3. of Quaternary structure of a G-protein-coupled receptor heterotetramer in complex with Gi and Gs

Controls of cAMP production and BRET assays in cells expressing minigenes and in cells expressing the ghrelin GHS1a receptor instead of one of the adenosine receptors. (A,B) cAMP determination in HEK-293T cells transfected with (A) 0.3 μg of cDNA corresponding to A1R or (B) with 0.2 μg of cDNA corresponding to A2AR with (control) or without 0.5 μg of cDNA corresponding to minigenes coding for peptides blocking either Gi or Gs binding. Cells were stimulated with the A1R agonist N6-Cyclopentyladenosine (CPA) (10 nM, red bars) in the presence of 0.5 μM forskolin (Fk) or with the A2AR agonist 4-[2-[[6-Amino-9-(N-ethyl-β-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride (CGS-21680) (200 nM, blue bars). Values expressed as % of the forskolin-treated cells (CPA reduces forskolin-induced cAMP levels, red bars) or of the basal (CGS 21680 per se enhances cAMP levels, blue bars) are given as mean ± SD (n = 4–8). One-way ANOVA followed by a Bonferroni post - hoc test showed a significant effect of CPA when compared with that of forskolin (red bars, ***p