The angiotensin receptors are a class of G protein-coupled receptors with angiotensins as ligands. They are important in the renin-angiotensin system: they are responsible for the signal transduction of the main effector hormone.

Structure

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

Members

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AT₁

The AT₁ receptor is the best elucidated angiotensin receptor. It is coupled to phospholipase C and angiotensin II increases the cytosolic Ca²⁺ level. It also inhibits adenylate cyclase and activate various tyrosine kinases. Effects mediated by the AT₁ receptor include vasoconstriction, aldosterone synthesis and secretion, increased vasopressin secretion, cardiac hypertrophy, augmentation of peripheral noradrenergic activity, vascular smooth muscle cells proliferation, decreased renal blood flow, renal renin inhibition, renal tubular sodium reuptake, modulation of central sympathetic nervous system activity, cardiac contractility, central osmocontrol and extracellular matrix formation.

AT₂

AT₂ receptors are more plentiful in the foetus and neonate. Effects mediated by the AT₂ receptor include inhibition of cell growth, fetal tissue development, modulation of extracellular matrix, neuronal regeneration, apoptosis, cellular differentiation and maybe vasodilation.

AT₃ and AT₄

Other poorly characterized subtypes include AT₃ receptor and AT₄ receptor. The AT₄ receptor is activated by the angiotensin II metabolite angiotensin IV, and may play a role in regulation of the CNS extracellular matrix.

See also

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• Angiotensin II receptor antagonist

External links

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• (AGTR1), (AGTR2)

G protein coupled receptors