... GPCR–b-arres-tin interaction. (A) The sequential binding of the ligands to each half of the receptordimer induces the recruitment of twomolecules of b-arrestin and then theactivation of ERK. (B) ... to think that, in cells coexpressingtwo receptors, most of them are in a homo-oligomericform. In spite of this indication, however, internalizat-ion of b2-adrenergic receptors, as induced ... results in synergistic inhibition of adenylate cyclase [8]. Similarly, coexpression of angiotensin I and bradykinin B2receptors in HEK-293cells increases the efficacy and potency of angiotensinII,...