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PsychedeliaDokholyan Laboratory
TargetUnclassified

H3

Matched no rule. Shown as-is rather than assigned a class by guesswork. Values below are reported as measured; because this is not a molecular target, they are not treated as affinities anywhere on this site.

Measurements
21
Compounds
15
Binding constants
6
Median pX
5.64

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

HRH3_HUMANHRH3Homo sapiens

Histamine H3 receptor

The H3 subclass of histamine receptors could mediate the histamine signals in CNS and peripheral nervous system. Signals through the inhibition of adenylate cyclase and displays high constitutive activity (spontaneous activity in the absence of agonist). Agonist stimulation of isoform 3 neither modified adenylate cyclase activity nor induced intracellular calcium mobilization

Quoted from UniProt’s FUNCTION annotation for Q9Y5N1 (reviewed).

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
HDC0.7900.0000.0000.790
DRD10.7820.3220.0000.658
CLIC40.7700.0000.0000.770
HNMT0.7200.0000.0000.720
DRD20.7070.3220.0000.505
HRH20.6840.0000.0000.679
TPM30.6120.0000.0000.612
SLC16A80.5970.0000.0000.588
BCHE0.5750.0000.0000.575
AQP10.5590.0000.0000.547

Where it sits in the cell

UniProt, curated Cell membrane

Expression by cell type

Single cell type RNA, the 6 highest of those the Human Protein Atlas reports for this gene. Transcript, not protein, and a cell type rather than a tissue.

  • Brain inhibitory neurons44.6 nCPM
  • Other brain neurons30.1 nCPM
  • Retinal ganglion cells15.5 nCPM
  • Brain excitatory neurons11.1 nCPM
  • Retinal amacrine cells7.6 nCPM
  • Bergmann glia4.3 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.

  • brain51.9 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 — 26.0 nTPM, from HRH3cerebellum — 37.3 nTPM, from HRH3hippocampal formation — 10.3 nTPM, from HRH3amygdala — 13.3 nTPM, from HRH3hypothalamus — 35.0 nTPM, from HRH3thalamus — no resolved target expressed herebasal ganglia — 51.9 nTPM, from HRH3medulla 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: midbrain 5.8, spinal cord 2.4, pituitary gland 1.8, retina 0.5.

Body

heart — no resolved target expressed heresmooth muscle — no resolved target expressed herelung — no resolved target expressed hereliver — no resolved target expressed herekidney — no resolved target expressed herestomach — no resolved target expressed hereduodenum — no resolved target expressed heresmall intestine — no resolved target expressed herecolon — no resolved target expressed hereadrenal gland — 0.4 nTPM, from HRH3thyroid gland — no resolved target expressed herepancreas — no resolved target expressed hereurinary bladder — 0.2 nTPM, from HRH3skeletal muscle — no resolved target expressed herespleen — no resolved target expressed heresalivary gland — no resolved target expressed here
052 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 HRH3 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 ganglia51.9 nTPM
  • cerebellum37.3 nTPM
  • hypothalamus35.0 nTPM
  • cerebral cortex26.0 nTPM
  • amygdala13.3 nTPM
  • hippocampal formation10.3 nTPM
  • midbrain5.8 nTPM
  • spinal cord2.4 nTPM
  • pituitary gland1.8 nTPM
  • retina0.5 nTPM

Peripheral and autonomic · 2

  • adrenal gland0.4 nTPM
  • urinary bladder0.2 nTPM

Transcript is not protein. These are RNA levels for HRH3, 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.

III · Ranking

Compounds by strongest binding constant

One bar per compound: its strongest Ki or Kd at this target, expressed as pX. Compounds measured here only by a functional assay do not appear — they are in the table below.

  1. 015-MeO-DALT5.77
  2. 02Cannabidiol5.51
  3. 03Mitragynine5.09

IV · Evidence

Every measurement at this target

Each row links to the ChEMBL assay it came from.

Equilibrium binding constants 6

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

TargetClassTypeValue (nM)pXOrganismAssay
H3UnclassifiedKi1,6985.77Homo sapiensCHEMBL3756493
H3UnclassifiedKi1,7125.77GUINEA PIGPMID 29499272
H3UnclassifiedKi3,1005.51Homo sapiensCHEMBL4687695
H3UnclassifiedKi8,0675.09HUMANPDSP
H3UnclassifiedKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL3756493
H3UnclassifiedKi— no normalized value— value does not convert to pXHomo sapiensCHEMBL2395818

Functional readouts 14

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

TargetClassTypeValue (nM)pXOrganismAssay
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291812
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291812
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291812
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291812
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291812
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921
H3UnclassifiedAC50— no normalized value— value does not convert to pXHomo sapiensCHEMBL5291921

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
H3UnclassifiedInhibition— no normalized value— value does not convert to pXHomo sapiensCHEMBL4687686
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