Angiotensin II receptor type 1 or AT₁ receptor is one of the receptors that binds the octapeptide hormone Angiotensin II (Ang II). 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.