Functional interactions within the angiotensin AT1 receptor oligomers ‐ the role of the conserved DRY motif

Abstract

In this study we investigated the functional consequences of intradimeric interactions within type I angiotensin receptor (AT1R) homodimer. To achieve this, we stimulated selectively one protomer of the AT1R dimer, and followed the activation process of the other protomer. For the selective stimulation, we used the S109Y mutant AT1R which is resistant to the non peptide AT1R antagonists like candesartan. Expressing this mutant receptor together with the wild type in CHO cells, in the presence of candesartan we could examine the interaction between them by stimulating the S109Y mutant receptor, and following the activation of the wild type receptor. The activation of the wild type receptor was monitored either by measuring the interaction between the receptor and β‐arrestin2 or by following the conformational changes of the receptor with an intramolecular biosensor. Under these conditions we could detect conformational changes and β‐arrestin2 binding of the nonstimulated protomer. Introduction of the DRY/AYY mutation into the directly activated protomer completely abolished the described effects, suggesting the crucial role of this motif in the intradimeric interactions.