Differential affinities of visual arrestin, beta arrestin1, and beta arrestin2 for G protein-coupled receptors delineate two major classes of receptors

Visual arrestin, beta arrestin1, and beta arrestin2 comprise a family of in tracellular proteins that desensitize G protein-coupled receptors (GPCRs), In addition, beta arrestin1 and beta arrestin2 target desensitized receptor s to clathrin-coated pits for endocytosis. Whether arrestins differ in thei r ability to interact with GPCRs in cells is not known, In this study, we v isualize the interaction of arrestin family members with GPCRs in real time and in live cells using green fluorescent protein-tagged arrestins, In the absence of agonist, visual arrestin and beta arrestin1 were found in both the cytoplasm and nucleus of HEK-293 cells, whereas beta arrestin2 was foun d only in the cytoplasm. Analysis of agonist-mediated arrestin translocatio n to multiple GPCRs identified two major classes of receptors, Class A rece ptors (beta 2 adrenergic receptor, mu opioid receptor, endothelin type A re ceptor, dopamine D1A receptor, and alb adrenergic receptor) bound beta arre stin2 with higher affinity than beta arrestin1 and did not interact with vi sual arrestin, In contrast, class B receptors (angiotensin II type 1A recep tor, neurotensin receptor 1, vasopressin V2 receptor, thyrotropin-releasing hormone receptor, and substance P receptor) bound both beta arrestin isofo rms with similar high affinities and also interacted with visual arrestin. Switching the carboxyl-terminal tails of class A and class B receptors comp letely reversed the affinity of each receptor for the visual and non-visual arrestins, In addition, exchanging the beta arrestin1 and beta arrestin2 c arboxyl termini reversed their extent of binding to class A receptors as we ll as their subcellular distribution. These results reveal for the first ti me marked differences in the ability of arrestin family members to bind GPC Rs at the plasma membrane, Moreover, they show that visual arrestin can int eract in cells with GPCRs other than rhodopsin. These findings suggest that GPCR signaling may be differentially regulated depending on the cellular c omplement of arrestin isoforms and the ability of arrestins to interact wit h other cellular proteins.