Figure 2.

a) First evaluation of the binding capacity by 1 μm CF-labeled hPP analogues 1b, 2–6 in transiently hY₄R-expressing COS-7 cells towards [³H]-hPP after a 90 min stimulation period. Total binding was set to 100% and corresponds to binding of radioligand in presence of H₂O in 1 % (w/v) BSA. Statistical analysis was performed by one-way ANOVA, followed by Dunnett's post-hoc test (GraphPad Prism 5.0). ***P ≤ 0.001, as compared to 1b (horizontal lines). b) For competition binding experiments, [³H]-hPP was displaced by increasing concentrations of most promising analogues 1, 3, 5 and 6. Assays were performed in triplicate; mean values ±SEM of independently examined experiments are shown.