TABLE 1

Effect of partner receptor ligands on agonist-induced G protein interaction to D1R-D3R heteromers

CODA-RET experiments were performed in human embryonic kidney-293 cells expressing dopamine receptor type 3 (D3R)-L1 and dopamine receptor type 1 (D1R)-L2 (D3R and D1R fused to the N-terminal and C-terminal hemitruncated Renilla luciferase 8 proteins, respectively) and G_αi1-yellow fluorescence protein (YFP) or G_αss-YFP. Bioluminescence resonance energy transfer between complemented hemitruncated Renilla luciferase 8 and G protein-mVenus was determined as a function of increasing concentrations of quinpirole or (±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide (SKF 38393) in the absence or in the presence of 1 μM SKF 38393, (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH 23390), quinpirole, or raclopride, as indicated in Table 1. From the dose-response curves, EC₅₀ values were calculated, and one-way analysis of variance, followed by post hoc Newman-Keuls test, did not show significant differences between EC₅₀ values.