Summary of AHR

This receptor has been shown to regulate xenobiotic-metabolizing enzymes such as cytochrome P450.

AHR binds several exogenous ligands such as natural plant flavonoids, polyphenolics and indoles, as well as synthetic polycyclic aromatic hydrocarbons and dioxin-like compounds. AhR is a cytosolic transcription factor that is normally inactive, bound to several co-chaperones. Upon ligand binding to chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the chaperones dissociate resulting in AhR translocating into the nucleusand dimerizing with ARNT (AhR nuclear translocator), leading to changes in gene transcription.

Ahr ligands have been generally classified into two categories, synthetic or naturally occurring. The first ligands to be discovered were synthetic and members of the halogenated aromatic hydrocarbons (polychlorinated dibenzodioxins, dibenzofurans and biphenyls) and polycyclic aromatic hydrocarbons (3-methylcholanthrene,benzo[a]pyrene, benzanthracenes and benzoflavones).

Naturally occurring compounds that have been identified as ligands of Ahr include derivatives of tryptophan such as indigo dye and indirubin, tetrapyrroles such as bilirubin, the arachidonic acid metabolites lipoxin A4 andprostaglandin G, modified low-density lipoprotein and several dietary carotenoids.

7-ketocholesterol competitively inhibits Ahr signal transduction,


Ligand-activated transcriptional activator. Binds to the XRE promoter region of genes it activates. Activates the expression of multiple phase I and II xenobiotic chemical metabolizing enzyme genes (such as the CYP1A1 gene). Mediates biochemical and toxic effects of halogenated aromatic hydrocarbons. Involved in cell-cycle regulation. Likely to play an important role in the development and maturation of many tissues. Regulates the circadian clock by inhibiting the basal and circadian expression of the core circadian component PER1. Inhibits PER1 by repressing the CLOCK-ARNTL/BMAL1 heterodimer mediated transcriptional activation of PER1.

Protein names

Recommended name:

Aryl hydrocarbon receptor

Alternative name(s):

Ah receptor
Class E basic helix-loop-helix protein 76

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Top Gene-Substance Interactions

AHR Interacts with These Diseases

Substances That Increase AHR

Substances That Decrease AHR

Conditions with Increased Gene Activity

Conditions with Decreased Gene Activity