Angiotensin receptor
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The angiotensin receptors are a class of G protein-coupled receptors with angiotensins as ligands.
The AT1 and AT2 receptors are ~30% homologous, but have a similar affinity for angiotensin II which is their main ligand. They are important in the renin-angiotensin system.
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 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.
Other poorly characterized subtypes include AT3 receptor and AT4 receptor.
See also: