Ah receptor, a novel ligand-activated transcription factor.
The aryl hydrocarbon receptor (AhR) is widely distributed in vertebrates and is known to be involved in metabolism of xenobiotics including man-made chemicals, most of which act as a ligand for the receptor, although no endogenous ligand has yet been known. Upon binding a ligand, the receptor is activated to translocate to the nuclei, and during the nuclear translocation process, it is dissociated from the 90 kDa heat shock protein (Hsp90) to form a heterodimer with Arnt (Ah receptor nuclear translocator). The heterodimer complex binds a DNA response element termed xenobiotic responsive element (XRE) localized upstream of the target genes of many drug-metabolizing enzymes including cytochrome P4501A1 and glutathione S-transferase to activate their transcription. Recent cDNA cloning has revealed that the AhR, like Arnt, possesses characteristic structural motifs of basic helix-loop-helix and PAS domains responsible for DNA recognition, heterodimerization, and ligand binding, and functions as a novel receptor-type transcription factor.
Sogawa
K
K
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai. sogawa@mail.cc.tohoku.ac.jp
Fujii-Kuriyama
Y
Y
D000818:Animals; D006801:Humans; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors