Catalytic activation of β-arrestin by GPCRs

β-arrestins are critical regulator and transducer proteins for G protein-coupled receptors (GPCRs). Cellular β-arrestin function is presently thought to require stable and stoichiometric GPCR/β-arrestin scaffold complex formation driven by the phosphorylated GPCR tail. We demonstrate a distinct and additional mechanism that does not require stable GPCR/β-arrestin scaffolding or the GPCR tail. Instead, it is activated by transient engagement of the GPCR core that destabilizes a conserved inter-domain charge network in β-arrestin. This promotes capture of β-arrestin at the plasma membrane and accumulation in clathrin-coated endocytic structures (CCSs) after GPCR dissociation, requiring a series of β-arrestin interactions with membrane phosphoinositides and CCS lattice proteins. β-arrestin clustering in CCSs without its upstream activating GPCR is associated with a β-arrestin-dependent component of the cellular ERK (Extracellular signal-regulated kinase) response. These results delineate a discrete mechanism of cellular β-arrestin function that is activated catalytically by GPCRs.