Detection of higher-order G protein-coupled receptor oligomers by a combined BRET-BiFC technique.

Despite some caveats, G protein-coupled receptor oligomerization is a phenomenon that is becoming largely accepted. Within these oligomers, however, stoichiometry remains to be elucidated. Here, by using bimolecular fluorescence complementation, we visualized adenosine A(2A) receptor homodimers in living cells, showing no apparent difference in the subcellular distribution when compared to the YFP-labelled adenosine A(2A) receptor protomer. Interestingly, the combination of bimolecular fluorescence complementation and bioluminescence resonance energy transfer techniques allowed us to detect the occurrence of adenosine A(2A) receptors oligomers containing more than two protomers. These results provide new insights into the molecular composition of G protein-coupled receptor oligomers.