Dynamics of apelin receptor/G protein coupling in living cells.

During our research on apelin receptor (APJ) signalling in living cells with BRET and FRET, we demonstrated that apelin-13 stimulation can lead to the activation of Gαi2 or Gαi3 through undergoing a molecular rearrangement rather than dissociation in HEK293 cells expressing APJ. Furthermore, Gαo and Gαq also showed involvement in APJ activation through a classical dissociation model. However, both FRET signal and BRET ratio between fluorescent Gαi1 subunit and Gβγ subunits demonstrated little change after apelin-13 stimulation. These results demonstrated that stimulation of APJ with apelin-13 causes activation of Gαi2, Gαi3, Gαo, Gαq; among which Gαi2, Gαi3 were activated through a novel rearrangement process. These results provide helpful data for understanding APJ mediated G-protein signalling.