The beta(2)-adrenergic receptor/beta arrestin complex recruits the clathrin adaptor AP-2 during endocytosis

beta arrestins mediate the desensitization of the beta(2)-adrenergic recept or (beta(2)AR) and many other G protein-coupled receptors (GPCRs), Addition ally, beta arrestins initiate the endocytosis of these receptors via clathr in coated-pits and interact directly with clathrin, Consequently, it has be en proposed that beta arrestins serve as clathrin adaptors for the GPCR fam ily by linking these receptors to clathrin lattices, AP-2, the heterotetram eric clathrin adaptor protein, has been demonstrated to mediate the interna lization of many types of plasma membrane proteins other than GPCRs, AP-2 i nteracts with the clathrin heavy chain and cytoplasmic domains of receptors such as those for epidermal growth factor and transferrin, In the present study we demonstrate the formation of an agonist-induced multimeric complex containing a GPCR, beta arrestin 2, and the beta 2-adaptin subunit of AP-2 , beta 2-Adaptin binds beta arrestin 2 in a yeast two-hybrid assay and coim munoprecipitates with beta arrrestins and beta(2)AR in an agonist-dependent manner in HEK-293 cells. Moreover, beta 2-adaptin translocates from the cy tosol to the plasma membrane in response to the beta(2)AR agonist isoproter enol and colocalizes with beta(2)AR in clathrin-coated pits. Finally, expre ssion of beta arrestin 2 minigene constructs containing the beta 2-adaptin interacting region inhibits beta(2)AR endocytosis. These findings point to a role for AP-2 in GPCR endocytosis, and they suggest that AP-2 functions a s a clathrin adaptor for the endocytosis of diverse classes of membrane rec eptors.