A b-Arrestin/Green Fluorescent Protein Biosensor for Detecting G Protein-coupled Receptor

G protein-coupled receptors (GPCR) represent the single most important drug targets for medical therapy, and information from genome sequencing and genomic data bases has substantially accelerated their discovery. The lack of a systematic approach either to identify the function of a new GPCR or to associate it with a cognate ligand has added to the growing number of orphan re-ceptors. In this work we provide a novel approach to this problem using a b-arrestin2/green fluorescent pro-tein conjugate (barr2-GFP). It provides a real-time and single cell based assay to monitor GPCR activation and GPCR-G protein-coupled receptor kinase or GPCR-ar-restin interactions. Confocal microscopy demonstrates the translocation of barr2-GFP to more than 15 different ligand-activated GPCRs. These data clearly support th