The conformational signature of β-arrestin2 predicts its trafficking and signalling functions

Nature. 2016 Mar 31;531(7596):665-8. doi: 10.1038/nature17154. Epub 2016 Mar 23.

Mi-Hye Lee 1, Kathryn M Appleton 1, Erik G Strungs 1, Joshua Y Kwon 1, Thomas A Morinelli 1, Yuri K Peterson 2, Stephane A Laporte 3 4 5, Louis M Luttrell 1 6

1Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
2Department of Pharmaceutical &Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
3Department of Medicine, McGill University Health Center Research Institute, McGill University, Quebec H4A 3J1, Canada.
4Pharmacology and Therapeutics, McGill University, Quebec H3G 1Y6, Canada.
5Anatomy and Cell Biology, McGill University, Quebec H3A 0C7, Canada.
6Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401, USA.

PMID: 27007854 PMCID: PMC4973468 DOI: 10.1038/nature17154

Arrestins are cytosolic proteins that regulate G-protein-coupled receptor (GPCR) desensitization, internalization, trafficking and signalling. Arrestin recruitment uncouples GPCRs from heterotrimeric G proteins, and targets the proteins for internalization via clathrin-coated pits. Arrestins also function as ligand-regulated scaffolds that recruit multiple non-G-protein effectors into GPCR-based ‘signalsomes’. Although the dominant function(s) of arrestins vary between receptors, the mechanism whereby different GPCRs specify these divergent functions is unclear. Using a panel of intramolecular fluorescein arsenical hairpin (FlAsH) bioluminescence resonance energy transfer (BRET) reporters to monitor conformational changes in β-arrestin2, here we show that GPCRs impose distinctive arrestin ‘conformational signatures’ that reflect the stability of the receptor-arrestin complex and role of β-arrestin2 in activating or dampening downstream signalling events. The predictive value of these signatures extends to structurally distinct ligands activating the same GPCR, such that the innate properties of the ligand are reflected as changes in β-arrestin2 conformation. Our findings demonstrate that information about ligand-receptor conformation is encoded within the population average β-arrestin2 conformation, and provide insight into how different GPCRs can use a common effector for different purposes. This approach may have application in the characterization and development of functionally selective GPCR ligands and in identifying factors that dictate arrestin conformation and function.

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