Figure 3.

Dimerization between D2R and GHSR1a. Proposed signaling through D2R involves coupling to a G_i pathway, which typically does not involve intracellular Ca²⁺ accumulation from the endoplasmic reticulum. Dimerization with GHSR1a, in the absence of a ghrelin ligand leads to a PLC-dependent accumulation of Ca²⁺. D2R’s G_βγ subunit acts to stimulate PLC activity, and α_i coupling by D2R is also required for Ca²⁺ accumulation. In contrast, Gα_q activity associated with GHSR1a is not required for D2R-induced Ca²⁺ accumulation. It is believed that the D2R-GHSR1a dimer is responsible for the anorectic effects of D2R agonists such as cabergoline.