Why does ARNT2 behave differently from ARNT

摘要: The aryl hydrocarbon receptor nuclear translocator (ARNT) is a member of the bHLH PAS (basic helix–loop–helix Period/ARNT/Single-minded) family transcription factors. It obligatory dimerization partner for many other members this family, including (AHR) and hypoxia-inducible factors 1α 2α (HIF-1/2α). Agonists AHR include variety environmentally important toxicants, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polycyclic aromatic hydrocarbons (PAHs) such as 3-methylcholanthrene (3MC) benzo[a]pyrene (BAP). mechanism transcriptional activation by best understood CYP1A1 gene. After binding ligand, translocates into nucleus dimerizes with ARNT. AHR/ARNT heterodimer then binds to specific regulatory sequences, termed xenobiotic response elements (XREs), in enhancer regions (and responsive genes). Transcriptional coactivators associated dimer it resides on region. These turn direct recruitment RNA polymerase II (pol II) general promoter genes, resulting initiation those genes. genes (as yet not fully defined) fashion believed underlie toxic effects TCDD, its potent carcinogenicity. Metabolism PAHs enzymes that are upregulated via critically impact carcinogenic activities these compounds.