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Fig. 4 | BMC Biology

Fig. 4

From: Cross-communication between Gi and Gs in a G-protein-coupled receptor heterotetramer guided by a receptor C-terminal domain

Fig. 4

Effect of interference peptides on receptor signaling. a cAMP production was determined in HEK-293 T cells transfected with 0.4 μg of A1R and A2AR cDNAs. Cells were treated for 4 h with medium (control) or with 4 μM A2AR TM synthetic peptides (TM1 to TM7, see Methods). Cells were unstimulated (basal, dotted line) or stimulated with forskolin (Fk, 0.5 μM, gray bars), with forskolin and the A1R agonist CPA (100 nM, black bars), the A2AR agonist CGS-21680 (100 nM, white bars), or with CPA and CGS-21680 (striped bars). Increases in cAMP percentage accumulation in relation to unstimulated cells. Mean ± SEM (7 experiments/condition). One-way ANOVA followed by Bonferroni’s post-hoc test showed a significant effect over basal in samples treated with CGS-21680 or CGS-21680 plus CPA, or over forskolin in samples treated with CPA (*P < 0.05, **P < 0.01, ***P < 0.001). One-way ANOVA followed by Bonferroni’s post-hoc test showed a significant effect over control in the absence of peptide (&P < 0.05, &&P < 0.01). b Intermolecular distances (depicted as double arrows in the adjacent schematic representation) were obtained from MD simulations of A1-A2AHet in complex with Gi and GsiAH and αsAH were modeled in the open conformation, see Additional file 1: Figure S2B) in the presence of the TAT-fused TM6 peptide, which alters the heteromer interface between A1R and A2AR. A representative snapshot of the molecular model is shown, viewed from the intracellular site. The TAT-TM6 peptide is shown in purple, whereas the color code of the depicted proteins is as in Fig. 3

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