Heterodimerization with CXCR7 changes the ability of CXCR4 to interact with Gαi1 proteins. BRET saturation assays were performed in parental (HEK-293T) or in CXCR7-expressing (HEK-293T/CXCR7) cells by transfecting a constant amount of the Gαi1-Rluc fusion protein and increasing amounts of CXCR4-YFP, in the presence or absence of 1 μM CXCL12. The curves obtained were fitted and BRET signals were determined. Data represent 3 independent experiments. In parental or in CXCR7-expressing cells, BRETmax signals were significantly increased by CXCL12 compared with basal conditions (P < .05). BRETmax signals were significantly different in the presence of CXCR7 compared with parental cells in basal conditions and in the presence of CXCL12 (P < .01).
