Detection of RXFP3 G protein interactions following treatment with H3 relaxin, H2 relaxin or R3(BΔ23–27)R/I5. Flp-In CHO cells were transiently co-transfected with RXFP3 Rluc8, Gγ2-Venus, Gβ1 and one of Gα subunits (Gαi2, Gαi3, GαoA, GαoB, Gαs, Gαq). Interactions between RXFP3 and G proteins were detected prior to and after treatment with H3 relaxin (10−6 M), H2 relaxin (10−6 M) or R3(BΔ23–27)R/I5 (10−6 M) using real-time BRET. H3 relaxin induced interactions between RXFP3 and Gαi2, Gαi3, GαoA or GαoB (A–D). H2 relaxin or R3(BΔ23–27)R/I5 induced interactions only between RXFP3 and Gαi2 or GαoB proteins and with a smaller signal compared with H3 relaxin (A, D). The ligand-induced BRET ratios were calculated by subtracting the ratio for the vehicle-treated sample from the BRET ratio for each ligand-treated sample as described. Data shown are mean ± SEM of four independent experiments. Illustration of the BRET interaction between receptor and G-protein subunits (G).