Aryl Hydrocarbon Receptor

The aryl hydrocarbon receptor (also known as AhR, AHR, ahr, ahR, or dioxin receptor) is a protein that in humans is encoded by the AHR gene. The aryl hydrocarbon receptor is a transcription factor that regulates gene expression. It was originally thought to function primarily as a sensor of xenobiotic chemicals and also as the regulator of enzymes such as cytochrome P450s that metabolize these chemicals. The most notable of these xenobiotic chemicals are aromatic (aryl) hydrocarbons from which the receptor derives its name. More recently, it has been discovered that AhR is activated (or deactivated) by a number of endogenous indole derivatives such as kynurenine. In addition to regulating metabolism enzymes, the AhR has roles in regulating immunity, stem cell maintenance, and cellular differentiation.