TargetEnzymes

Cytochrome P450 2A13

Named enzymes, including the metabolising cytochromes and the monoamine oxidases.

Measurements: 2
Compounds: 1
Binding constants: 2
Median pX: 5.04

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

CP2AD_HUMANCYP2A13Homo sapiens

Cytochrome P450 2A13

Exhibits a coumarin 7-hydroxylase activity. Active in the metabolic activation of hexamethylphosphoramide, N,N-dimethylaniline, 2'-methoxyacetophenone, N-nitrosomethylphenylamine, and the tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Possesses phenacetin O-deethylation activity

Quoted from UniProt’s FUNCTION annotation for Q16696 (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.

Partner	Combined	Experiment	Database	Text mining
CYP3A4	0.956	0.076	0.907	0.396
CYP3A5	0.950	0.076	0.907	0.308
CYP1A2	0.944	0.000	0.911	0.236
UGT2B17	0.942	0.000	0.905	0.383
UGT1A7	0.942	0.000	0.907	0.384
UGT1A4	0.942	0.000	0.907	0.385
UGT1A9	0.941	0.000	0.907	0.382
UGT2B7	0.941	0.000	0.905	0.369
UGT1A1	0.940	0.000	0.907	0.363
UGT1A8	0.940	0.000	0.907	0.364

Where it sits in the cell

UniProt, curated Endoplasmic reticulum membrane · Microsome membrane

Expression by cell type

Single cell type RNA, the 2 highest of those the Human Protein Atlas reports for this gene. Transcript, not protein, and a cell type rather than a tissue.

Conjunctival goblet cells109.7 nCPM
Respiratory secretory cells74 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.

liver1.9 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

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

Body

02 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 CYP2A13 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.

Peripheral and autonomic · 3

liver1.9 nTPM
lung0.1 nTPM
urinary bladder0.1 nTPM

Transcript is not protein. These are RNA levels for CYP2A13, 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.

01Tryptamine5.28

IV · Evidence

Every measurement at this target

Each row links to the ChEMBL assay it came from.

Equilibrium binding constants 2

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

Target	Class	Type	Value (nM)	pX	Organism	Assay
Cytochrome P450 2A13	Enzymes	Kd	5,200	5.28	Homo sapiens	CHEMBL3535230
Cytochrome P450 2A13	Enzymes	Ki	16,000	4.80	Homo sapiens	CHEMBL3532208

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