Ang II is the peptide hormone that generates most of the known effects of the renin-angiotensin system (RAS). Ang II is generated from the angiotensinogen protein by the actions of renin, angiotensin converting enzyme (ACE) and other peptidases. Ang II has a central role in cardiovascular homeostasis by regulating vasoconstriction, renal Na⁺ and water readsorption. In addition, Ang II induces cell growth and proliferation and has pro-inflammatory effects.

Most of the physiological actions of Ang II are mediated by AT₁ a member of the 7-transmembrane domain, G protein-coupled receptor (GPCR) superfamily. AT₂ is also a GPCR, and is largely believed to have counter-regulatory roles to the ones exerted through the AT₁ receptor. Hence, binding of Ang II to the AT₂ receptor will result in growth arrest and apoptosis, vasodilatation and hypotension.