Angiotensin receptor

angiotensin II receptor, type 1
Identifiers
Symbol	AGTR1
Alt. symbols	AGTR1B
IUPHAR	34
Entrez	185
HUGO	336
OMIM	106165
RefSeq	NM_000685
UniProt	P30556
Other data
Locus	Chr. 3 q21-q25

angiotensin II receptor, type 2
Identifiers
Symbol	AGTR2
IUPHAR	35
Entrez	186
HUGO	338
OMIM	300034
RefSeq	NM_000686
UniProt	P50052
Other data
Locus	Chr. X q22-q23

The angiotensin receptors are a class of G protein-coupled receptors with angiotensin II as their ligands. 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.

Structure

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

Members

Overview table

Receptor	Mechanism
AT1	Gq/11 Gi/o
AT2	Gi2 / 3
AT3
AT4

Losartan is a selective AT1 antagonist,while PD123177 is a selective AT2 antagonist.Both subtypes are G-protein coupled receptor.

AT₁

Main article: Angiotensin II receptor type 1

The AT₁ receptor is the best elucidated angiotensin receptor.

Location within the body

The AT1 subtype is found in the heart, blood vessels, kidney, adrenal cortex, lung and brain and mediates the vasoconstrictor effects.

Mechanism

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

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

Main article: 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.

AT₃ and AT₄

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.

See also

• Angiotensin II receptor antagonist

External links

• Receptors, Angiotensin at the US National Library of Medicine Medical Subject Headings (MeSH)