Aryl Hydrocarbon Receptor

Aryl Hydrocarbon Receptor (AhR or AHR or ahr or ahR) is a protein that in humans is encoded by the AHR gene. The aryl hydrocarbon receptor is a ligand-activated transcription factor involved in the regulation of biological responses to planar aromatic (aryl) hydrocarbons, and regulates xenobiotic-metabolizing enzymes such as cytochrome P450s, most notably cyp 1A1.

Aryl Hydrocarbon Receptor is a member of the family of basic helix-loop-helix transcription factors. AhR binds several exogenous ligands including 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, binding 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 nucleus and dimerizing with ARNT (AhR nuclear translocator), leading to changes in gene transcription.