Figure 6.

Displacement assay at Nluc‐CMKLR1 and Nluc‐GPR1 with TAMRA‐C9 and [K¹⁴¹(TAMRA)]ChemS157. All assays were performed using transiently transfected COS‐7 cells. TAMRA‐ligand was added with defined concentration and unlabeled ligand was used with increasing concentrations. Both were incubated for 1 h on ice to reach an equilibrium. BRET signal was detected directly after addition of coelenterazine h. Each assay was performed at least three times in triplicates. A and C represent the displacement binding BRET assay results of [K¹⁴¹(TAMRA)]ChemS157 (A) and TAMRA‐C9 (C) at Nluc‐CMKLR1. Full‐length protein results in sigmoidal displacement curves at Nluc‐CMKLR1. For TAMRA‐C9 no displacement curves at Nluc‐CMKLR1 can be plotted. The displacement BRET assay of [K¹⁴¹(TAMRA)]ChemS157 (B) and TAMRA‐C9 (D) with the corresponding unlabeled ligand at Nluc‐GPR1 result in sigmoidal displacement curves in both cases.