Angiotensin II receptor#at1

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

===AT₁===

{{Main|Angiotensin II receptor type 1}}

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{{cite journal | vauthors = Allen AM, MacGregor DP, McKinley MJ, Mendelsohn FA | title = Angiotensin II receptors in the human brain | journal = Regulatory Peptides | volume = 79 | issue = 1 | pages = 1–7 | date = January 1999 | pmid = 9930578 | doi = 10.1016/S0167-0115(98)00138-4 | s2cid = 21317534 }} and mediates the vasoconstrictor effects.

The angiotensin receptor is activated by the vasoconstricting peptide angiotensin II. The activated receptor in turn couples to G_q/11 and G_i/o and thus activates phospholipase C and increases the cytosolic Ca²⁺ concentrations, which in turn triggers cellular responses such as stimulation of protein kinase C. Activated receptor also inhibits adenylate cyclase and activates 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.{{cite journal | vauthors = Catt KJ, Mendelsohn FA, Millan MA, Aguilera G | title = The role of angiotensin II receptors in vascular regulation | journal = Journal of Cardiovascular Pharmacology | volume = 6 | issue = Suppl 4 | pages = S575-86 | year = 1984 | pmid = 6083400 | doi = 10.1097/00005344-198406004-00004 | doi-access = free }}

===AT₂===

{{Main|Angiotensin II receptor type 2}}

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.{{cite journal | vauthors = D'Amore A, Black MJ, Thomas WG | title = The angiotensin II type 2 receptor causes constitutive growth of cardiomyocytes and does not antagonize angiotensin II type 1 receptor-mediated hypertrophy | journal = Hypertension | volume = 46 | issue = 6 | pages = 1347–54 | date = December 2005 | pmid = 16286564 | doi = 10.1161/01.HYP.0000193504.51489.cf | s2cid = 10812400 | doi-access = }} 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.{{cite journal | vauthors = Saavedra JM, Armando I | title = Angiotensin II AT2 Receptors Contribute to Regulate the Sympathoadrenal and Hormonal Reaction to Stress Stimuli | journal = Cellular and Molecular Neurobiology | volume = 38 | issue = 1 | pages = 85–108 | date = January 2018 | pmid = 28884431 | pmc = 6668356 | doi = 10.1007/s10571-017-0533-x }}

Other poorly characterized subtypes include the AT₃ and AT₄ receptors. The AT₄ receptor is activated by the angiotensin II metabolite angiotensin IV, and may play a role in regulation of the CNS extracellular matrix, as well as modulation of oxytocin release.{{cite journal | vauthors = Chai SY, Fernando R, Peck G, Ye SY, Mendelsohn FA, Jenkins TA, Albiston AL | title = The angiotensin IV/AT4 receptor | journal = Cellular and Molecular Life Sciences | volume = 61 | issue = 21 | pages = 2728–37 | date = November 2004 | pmid = 15549174 | doi = 10.1007/s00018-004-4246-1 | s2cid = 22816307 | pmc = 11924499 }}{{cite journal | vauthors = Vanderheyden PM | title = From angiotensin IV binding site to AT4 receptor | journal = Molecular and Cellular Endocrinology | volume = 302 | issue = 2 | pages = 159–66 | date = April 2009 | pmid = 19071192 | doi = 10.1016/j.mce.2008.11.015 | s2cid = 140205109 }}{{cite journal | vauthors = Wright JW, Harding JW | title = Brain renin-angiotensin--a new look at an old system | journal = Progress in Neurobiology | volume = 95 | issue = 1 | pages = 49–67 | date = September 2011 | pmid = 21777652 | doi = 10.1016/j.pneurobio.2011.07.001 | s2cid = 25955824 }}

• Angiotensin II receptor antagonist

{{Reflist}}

• {{MeshName|Receptors,+Angiotensin}}

{{G protein-coupled receptors}}

{{Neuropeptide receptors}}

{{Angiotensin receptor modulators}}

{{DEFAULTSORT:Angiotensin receptor}}

Category:G protein-coupled receptors