Mean EC50 values and amplitude of responses for cAMP concentration-response curves in Figure 5.

EC50 values were determined for each individual experiment, using a sigmoidal dose-response equation. Compared to wild-type receptors, the EC50 values for N77Q-GIPR and N63,82,115Q-GLP-1R were significantly right shifted, as shown by a one-way ANOVA analysis followed by Dunnett's multiple comparison test. The changes in RFU values for the N62,77Q-GIPR were small and could not be accurately fitted. The amplitude of response was calculated by subtracting the lowest RFU values from the highest for each individual experiment.