Internalization of the rat AT1a and AT1b receptors: pharmacological and functional requirements

The capacity of the angiotensin II (AngII) agonist [Sar1]AngII, the antagonist [Sar1‐I1e8]AngII and the non‐peptidic antagonist DuP753 to undergo receptor internalization were studied in Chinese hamster ovary cells expressing rat AngII type 1a or 1b receptors (AT1a or AT1b) or a mutant of AT1a (Asn74) unable to couple G‐protein. In this expression system, the ligand‐induced internalization of rat AT1a and AT1b are similar. Moreover, peptidic ligands, either the agonist or antagonist, induce a significant internalization of AT1 receptors, but the non‐peptidic antagonist DuP753 is far less potent. Finally, the normal internalization of the mutant Asn74 demonstrates that receptor activation and G‐protein coupling are not required for AT1ainternalization.