Fig 4.

Bar plot representation of the calcium mobilized (A) and cAMP produced (B) upon activation of the TP or IP and chimeric receptors. The cells expressing the IP were stimulated with the IP agonist iloprost, while cells expressing the TP and TP-IP chimeras were stimulated with the TP agonist U46619. Shown are the agonist-independent or basal activities (−) and the activities after stimulation (+) with a single saturating concentration (1 μM) of agonists to determine the maximal agonist-induced or intrinsic signals. The results were normalized to the amounts of calcium mobilized and cAMP produced relative to cell surface expression of the receptors as determined by FACS. The results are from a minimum of 3 independent experiments performed in duplicate. A one-way ANOVA with Tukey's post hoc test was used to check the significance levels of the amounts of calcium mobilized or cAMP produced. The single asterisks indicate a significant difference in the amount of cAMP produced or calcium mobilized at the highest concentration of agonist with respect to the WT TP (for cAMP produced) or WT IP (for calcium mobilized) (P < 0.05). The double asterisks indicate calcium mobilization at a basal level compared to WT IP basal level activity and cAMP produced at a basal level compared to WT TP basal activity (P < 0.05). The bar plots do not include the chimeras TP ICL3-IP and TP ICL3A-IP, as they failed to show any dose-dependent response. The error bars represent means ± standard deviation (SD).