Histamine H2 receptor

Histamine receptor H2
Identifiers
Symbols	HRH2 ; H2R
External IDs	OMIM: 142703 MGI: 108482 HomoloGene: 40613 IUPHAR: 263 ChEMBL: 1941 GeneCards: HRH2 Gene
Gene ontology Molecular function • dopamine neurotransmitter receptor activity, coupled via Gs • histamine receptor activity • dopamine binding Cellular component • plasma membrane • integral component of plasma membrane Biological process • histamine-induced gastric acid secretion • gastrin-induced gastric acid secretion • synaptic transmission, dopaminergic • epithelial cell morphogenesis • immune response • G-protein coupled receptor signaling pathway, coupled to cyclic nucleotide second messenger • adenylate cyclase-activating dopamine receptor signaling pathway • sensory perception of chemical stimulus • learning • memory • visual learning • positive regulation of adenylate cyclase activity involved in G-protein coupled receptor signaling pathway • positive regulation of vasoconstriction • regulation of synaptic plasticity • digestive tract development • gland development • phospholipase C-activating dopamine receptor signaling pathway • toxin transport Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	3274	15466
Ensembl	ENSG00000113749	ENSMUSG00000034987
UniProt	P25021	P97292
RefSeq (mRNA)	NM_001131055	NM_001010973
RefSeq (protein)	NP_001124527	NP_001010973
Location (UCSC)	Chr 5: 175.66 – 175.69 Mb	Chr 13: 54.19 – 54.22 Mb
PubMed search	[1]	[2]

H₂ receptors are positively coupled to adenylate cyclase via G_s. It is a potent stimulant of cAMP production, which leads to activation of Protein Kinase A. PKA functions to phosphorylate certain proteins, affecting their activity. The drug betazole is an example of a Histamine H₂ receptor agonist.

Function

Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Its various actions are mediated by histamine receptors H₁, H₂, H₃ and H₄. The histamine receptor H₂ belongs to the rhodopsin-like family of G protein-coupled receptors. It is an integral membrane protein and stimulates gastric acid secretion. It also regulates gastrointestinal motility and intestinal secretion and is thought to be involved in regulating cell growth and differentiation.

Tissue distribution

It is found here:

• Gastric parietal cells (oxyntic cells)
• Vascular smooth muscle
• Neutrophils
• Central nervous system
• Heart
• Uterus

Physiological responses

Activation of the H₂ receptor results in the following physiological responses:

• Stimulation of gastric acid secretion (Target of anti-histaminergics (H2 receptors) for peptic ulcer disease and GERD)
• Smooth muscle relaxation (Experimental histamine H2 receptor agonist used for asthma and COPD)
• Inhibit antibody synthesis, T-cell proliferation and cytokine production
• Vasodilation – PKA activity causes phosphorylation of MLCK, decreasing its activity, resulting in MLC of myosin being dephosphorylated by MLCP and thus inhibiting contraction. The smooth muscle relaxation leads to vasodilation.

See also

• H2-receptor antagonist

External links

• H2 receptors at the US National Library of Medicine Medical Subject Headings (MeSH)

This article incorporates text from the United States National Library of Medicine, which is in the public domain.