Recent progress in molecular mechanisms of angiotensin II type 1 and 2 receptors

The renin-angiotensin system hormone angiotensin II Ang II plays a central role in the pathophysiology of vasoconstriction, cardiovascular hypertrophy and hyperplasia. Two distinct subtypes of Ang II receptor, type 1 AT1 and type 2 AT2, have been identified, and both have been shown to belong to the G protein-coupled receptors (GPCRs) superfamily. AT1 and AT2 receptors may have antagonistic action. While the crystal structures of GPCRs obtained from the rhodopsin, opsin, and ß1 and ß2- adrenergic receptors have recently been described in different conformational states, the crystal structures of Ang II receptors have not been elucidated. The conformation range and dynamics of the effects of ligands on GPCRs may differ from one receptor to another. This review focuses on the structure and function of Ang II receptors, such as the movement of transmembrane helices, functional selectivity for AT1 receptor activation, the possibility of constitutive activity of wild-type Ang II receptors and the homo- and hetero-dimerization of Ang II receptors.