Angiotensin II receptor

The angiotensin II receptors, (ATR1) and (ATR2), are a class of G protein-coupled receptors with angiotensin II as their ligands.^[1] They are important in the renin–angiotensin system: they are responsible for the signal transduction of the vasoconstricting stimulus of the main effector hormone, angiotensin II.^[2]

The AT₁ and AT₂ receptors share a sequence identity of ~30%, but have a similar affinity for angiotensin II, which is their main ligand.

The AT₁ receptor is the best elucidated angiotensin receptor.

The AT1 subtype is found in the heart, blood vessels, kidney, adrenal cortex, lung and circumventricular organs of brain, basal ganglia, brainstem^[4] and mediates the vasoconstrictor effects.

The angiotensin receptor is activated by the

AT₂ receptors are more plentiful in the fetus and neonate. The AT₂ receptor remains enigmatic and controversial – is probably involved in vascular growth. Effects mediated by the AT₂ receptor are suggested to include inhibition of cell growth, fetal tissue development, modulation of extracellular matrix, neuronal regeneration, apoptosis, cellular differentiation, and maybe vasodilation and left ventricular hypertrophy.^[6] In humans the AT2 subtype is found in molecular layer of the cerebellum. In the mouse is found in the adrenal gland, amygdaloid nuclei and, in small numbers, in the paraventricular nucleus of the hypothalamus and the locus coeruleus.^[7]

Other poorly characterized subtypes include the AT₃ and AT₄ receptors. The AT₄ receptor is activated by the angiotensin II metabolite