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PsychedeliaDokholyan Laboratory
TargetHistamine receptors

Histamine H2 receptor

H1–H4 receptor subtypes.

Measurements
17
Compounds
9
Binding constants
9
Median pX
—

I · Identity

What this target is

Its function as UniProt states it, where in a cell the protein is found, and which cell types and tissues transcribe its gene.

Protein

HRH2_HUMANHRH2Homo sapiens

Histamine H2 receptor

G protein-coupled receptor for histamine, primarily mediating gastric acid secretion. Predominantly expressed in the gastric mucosa, couples to G(s) G alpha proteins upon histamine binding, leading to activation of adenylate cyclase and increased intracellular cyclic AMP (cAMP) levels38647423,39333117. This signaling cascade stimulates parietal cells to secrete hydrochloric acid, playing a key role in digestive physiology. Also expressed in other tissues, including the heart and central nervous system, where it may contribute to cardiac stimulation and modulate neurotransmitter release (By similarity)

Quoted from UniProt’s FUNCTION annotation for P25021 (reviewed). The superscript numbers are UniProt’s own PubMed citations, kept in the sentence and in order, each linking to the paper it names.

What it acts with

STRING’s highest-confidence human functional partners. The combined score mixes several kinds of evidence, so each channel is shown separately — a partner supported by experiment is a different claim from one supported only by text mining, and for a receptor this is where its coupling appears as evidence rather than as assertion.

PartnerCombinedExperimentDatabaseText mining
GNAS0.9510.2970.9000.362
ATP12A0.8800.0000.0000.880
ATP4A0.8800.0000.0000.880
GNAL0.7990.2970.6500.249
HDC0.7990.0000.0000.791
GAST0.7650.1340.0000.731
HRH30.6840.0000.0000.679
IL130.6120.0000.0000.611
IL40.6100.0000.0000.600
IL30.6050.0000.0000.572

Where it sits in the cell

UniProt, curated Cell membrane

Expression by cell type

Single cell type RNA, the 10 highest of those the Human Protein Atlas reports for this gene. Transcript, not protein, and a cell type rather than a tissue.

  • Neutrophils601.2 nCPM
  • Parietal cells160.9 nCPM
  • Neutrophil progenitors149 nCPM
  • Monocyte progenitors130 nCPM
  • monocytes102.1 nCPM
  • Vascular smooth muscle cells90.3 nCPM
  • Brain inhibitory neurons68.6 nCPM
  • Breast lactating cells61.5 nCPM
  • Microglia61.4 nCPM
  • pDCs53.7 nCPM

Expression by tissue

The tissues this gene is enriched in, by consensus RNA. A tissue absent from this list is one the Atlas does not call specific for this gene, which is not the same as absent from it.

  • bone marrow25.7 nTPM
  • heart muscle15.7 nTPM

II · Anatomy

Where the gene is transcribed

The same two atlases the compound plates use, asked about this gene alone. Brain on the left, peripheral and autonomic tissues on the right.

Brain

cerebral cortex — 5.0 nTPM, from HRH2cerebellum — 0.2 nTPM, from HRH2hippocampal formation — 1.4 nTPM, from HRH2amygdala — 1.7 nTPM, from HRH2hypothalamus — 0.7 nTPM, from HRH2thalamus — no resolved target expressed herebasal ganglia — 6.0 nTPM, from HRH2medulla oblongata — no resolved target expressed here

basal ganglia: drawn as the caudate nucleus, putamen and globus pallidus.

Measured but not drawn — this anatomogram has no outline for them: spinal cord 0.9, midbrain 0.8, pituitary gland 0.4, retina 0.2.

Body

heart — 15.7 nTPM, from HRH2smooth muscle — 2.6 nTPM, from HRH2lung — 4.1 nTPM, from HRH2liver — 0.4 nTPM, from HRH2kidney — 1.0 nTPM, from HRH2stomach — 10.0 nTPM, from HRH2duodenum — 4.6 nTPM, from HRH2small intestine — 4.7 nTPM, from HRH2colon — 0.7 nTPM, from HRH2adrenal gland — 0.9 nTPM, from HRH2thyroid gland — 0.9 nTPM, from HRH2pancreas — 1.0 nTPM, from HRH2urinary bladder — 2.8 nTPM, from HRH2skeletal muscle — 0.4 nTPM, from HRH2spleen — 7.1 nTPM, from HRH2salivary gland — 0.8 nTPM, from HRH2
016 nTPM

Square-root ramp · shared scale across both plates

Shading is transcript level — not affinity, and not affinity combined with expression. Outlined but unshaded organs hold none of HRH2 transcript above the atlas’s detection threshold. Anatomy from EMBL-EBI Anatomogram (Apache License 2.0); regions identified by Uberon (uberon.org), CC BY 3.0.

Brain · 10

  • basal ganglia6.0 nTPM
  • cerebral cortex5.0 nTPM
  • amygdala1.7 nTPM
  • hippocampal formation1.4 nTPM
  • spinal cord0.9 nTPM
  • midbrain0.8 nTPM
  • hypothalamus0.7 nTPM
  • pituitary gland0.4 nTPM
  • cerebellum0.2 nTPM
  • retina0.2 nTPM

Peripheral and autonomic · 16

  • heart muscle15.7 nTPM
  • stomach 110.0 nTPM
  • spleen7.1 nTPM
  • small intestine4.7 nTPM
  • duodenum4.6 nTPM
  • lung4.1 nTPM
  • urinary bladder2.8 nTPM
  • smooth muscle2.6 nTPM
  • kidney1.0 nTPM
  • pancreas1.0 nTPM
  • adrenal gland0.9 nTPM
  • thyroid gland0.9 nTPM
  • salivary gland0.8 nTPM
  • colon0.7 nTPM
  • liver0.4 nTPM
  • skeletal muscle0.4 nTPM

Transcript is not protein. These are RNA levels for HRH2, shaded on √nTPM so that a three-order range stays legible — on a linear ramp every region but the strongest would read as blank, which looks like absence rather than less. A region carrying no shading is one the atlas reports no consensus value for, not one where the gene is silent. And a gene being transcribed somewhere is not evidence that any compound reaches it. Human Protein Atlas, RNA expression, nTPM (normalized transcripts per million), consensus tissue dataset.

IV · Evidence

Every measurement at this target

Each row links to the ChEMBL assay it came from.

Equilibrium binding constants 9

Ki and Kd — a concentration at equilibrium. Directly comparable across rows at the same target.

TargetClassTypeValue (nM)pXOrganismAssay
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL2395819
Histamine H2 receptorHistamine receptorsKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL2395819

Functional readouts 7

IC₅₀, EC₅₀, AC₅₀ and potency. Assay-dependent, and not interchangeable with a binding constant.

TargetClassTypeValue (nM)pXOrganismAssay
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157
Histamine H2 receptorHistamine receptorsIC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL1909157

Other measurements 1

Everything else ChEMBL recorded for this compound — percentage inhibition, efficacy, half-life, cytotoxicity. Reported in the assay's own units, which is why no value is converted here.

TargetClassTypeValue (nM)pXOrganismAssay
Histamine H2 receptorHistamine receptorsInhibition— no normalized value— value does not convert to pXHomo sapiensCHEMBL4687681
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