II metabolizing enzymes consisting of CYP1A1, CYP1A2, CYP1B1, NQO1, ALDH3A1, UGT1A2 and GSTA1. Presumably, vertebrates have this function to be able to detect a wide range of chemicals, indicated by the wide range of substrates AhR is able to bind and facilitate their biotransformation and elimination. The AhR may also signal the presence of toxic chemicals in food and cause aversion of such foods. AhR activation seems to be also important for immunological responses and inhibiting inflammation through upregulation of interleukin 22 and downregulation of Th17 response. The Knockdown of AHR mostly downregulates the expression of innate immunity genes in THP-1 cells. Toxic response Extensions of the adaptive response are the toxic responses elicited by AhR activation. Toxicity results from two different ways of AhR signaling. The first is a side effect of the adaptive response in which the induction of metabolizing enzymes results in the production of toxic metabolites. For example, the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP), a ligand for AhR, induces its own metabolism and bioactivation to a toxic metabolite via the induction of CYP1A1 and CYP1B1 in several tissues. The second approach to toxicity is the result of aberrant changes in global gene transcription beyond those observed in the "AhR gene battery." These global changes in gene expression lead to adverse changes in cellular processes and function. Microarray analysis has proved most beneficial in understanding and characterizing this response. Protein-protein interactions In addition to the protein interactions mentioned above, AhR has also been shown to interact with the following: AIP ARNTL CCNT1 ESR1 NCOA1 NEDD8 NRIP1 RELA RELB RP References External links Receptors Transcription factors PAS-domain-containing proteins