Regulation of D1 Dopamine Receptor Trafficking and Signaling by Caveolin-1

Abstract

There is accumulating evidence that G protein-coupled recep-tor signaling is regulated by localization in lipid raft microdo-mains. In this report, we determined that the D1 dopamine receptor (D1R) is localized in caveolae, a subset of lipid rafts, by sucrose gradient fractionation and confocal microscopy. Through coimmunoprecipitation and bioluminescence reso-nance energy transfer assays, we demonstrated that this local-ization was mediated by an interaction between caveolin-1 and D1R in COS-7 cells and an isoform-selective interaction be-tween D1R and caveolin-1 in rat brain. We determined that the D1R interaction with caveolin-1 required a putative caveolin binding motif identified in transmembrane domain 7. Agonist stimulation of D1R caused translocation of D1R into caveolin-1-enriched sucrose fractions, which was determined to be