Interaction with beta-arrestin determines the difference in internalization behavior between beta(1)- and beta(2)-adrenergic receptors

The beta(1)-adrenergic receptor (beta(1)AR) shows the resistance to agonist -induced internalization. As beta-arrestin is important for internalization , we examine the interaction of beta-arrestin with beta(1)AR with three dif ferent methods: intracellular trafficking of beta-arrestin, binding of in v itro translated beta-arrestin to intracellular domains of beta(1)- and beta (2)ARs, and inhibition of beta AR-stimulated adenylyl cyclase activities by beta-arrestin. The green fluorescent protein-tagged beta-arrestin 2 transl ocates to and stays at the plasma membrane by beta(2)AR stimulation. Althou gh green fluorescent protein-tagged beta-arrestin 2 also translocates to th e plasma membrane, it returns to the cytoplasm 10-30 min after beta(1)AR st imulation. The binding of in vitro translated beta-arrestin 1 and beta-arre stin 2 to the third intracellular loop and the carboxyl tail of beta(1)AR i s lower than that of beta(2)AR, The fusion protein of beta-arrestin 1 with glutathione S-transferase inhibits the beta(1)- and beta(2)AR-stimulated ad enylyl cyclase activities, although inhibition of the beta(1)AR-stimulated activity requires a higher concentration of the fusion protein than that of the beta(1)AR-stimulated activity. These results suggest that weak interac tion of beta(1)AR with beta-arrestins explains the resistance to agonist-in duced internalization. This is further supported by the finding that beta-a rrestin can induce internalization of beta(1)AR when beta-arrestin 1 does n ot dissociate from beta(1)AR by fusing to the carboxyl tail of beta(1)AR.