Cellular trafficking of G protein-coupled receptor/beta-arrestin endocyticcomplexes

beta-Arrestins are multifunctional proteins identified on the basis of thei r ability to bind and uncouple G protein-coupled receptors (GPCR) from hete rotrimeric G proteins, In addition, beta-arrestins play a central role in m ediating GPCR endocytosis, a key regulatory step in receptor resensitizatio n. In this study, we visualize the intracellular trafficking of beta-arrest in2 in response to activation of several distinct GPCRs including the beta( 2)-adrenergic receptor (beta(2)AR), angiotensin II type 1A receptor (AT(1A) R), dopamine D1A receptor (D1AR), endothelin type A receptor (ETAR), and ne urotensin receptor (NTR). Our results reveal that in response to beta(2)AR activation, beta-arrestin2 translocation to the plasma membrane shares the same pharmacological profile as described for receptor activation and seque stration, consistent with a role for beta-arrestin as the agonist-driven sw itch initiating receptor endocytosis. Whereas redistributed beta-arrestins are confined to the periphery of cells and do not traffic along with activa ted beta(2)AR, D1AR, and ETAR in endocytic vesicles, activation of AT(1A)R and NTR triggers a clear time-dependent redistribution of beta-arrestins to intracellular vesicular compartments where they colocalize with internaliz ed receptors. Activation of a chimeric AT(1A)R with the beta(2)AR carboxyl- terminal tail results in a beta-arrestin membrane localization pattern simi lar to that observed in response to beta(2)AR activation. In contrast, the corresponding chimeric beta(2)AR with the AT(1A)R carboxyl-terminal tail ga ins the ability to translocate beta-arrestin to intracellular vesicles. The se results demonstrate that the cellular trafficking of beta-arrestin prote ins is differentially regulated by the activation of distinct GPCRs. Furthe rmore, they suggest that the carboxyl-tail of the receptors might be involv ed in determining the stability of receptor/beta-arrestin complexes and cel lular distribution of beta-arrestins.