Fig. 2.

cAMP concentration–response curves for polar TM boundary Ala mutants. Concentration–response curves for cAMP accumulation of wildtype and mutant receptors stimulated by GLP-1 (A, B), exendin-4 (C, D) or oxyntomodulin (E, F) in CHOFlpIn cells stably expressing wildtype or mutant receptors. Data are normalised to the response elicited by the wildtype receptor and analysed with an operational model agonism. All values are mean ± S.E.M of four to six independent experiments, conducted in duplicate.