Fig. 3.

Allosteric modulation of the GLP-1R occurs within a single receptor protomer. Concentration–response curves were generated for GLP-1(7-36)NH₂ (A, C, and E) and oxyntomodulin (B, D, and F) in the presence and absence of increasing concentrations of compound 2 (A–D) or BETP (E and F) in cAMP accumulation assays using Cos-1 cells expressing wild-type GLP-1R (Left) or G252A, L256A, V259A GLP-1R (Right). Data are normalized to maximal peptide response, are fitted with an operational model of allosterism, and are representative of the mean ± SEM of four independent experiments performed in duplicate.