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Gene Review

CYP1A1  -  cytochrome P450, family 1, subfamily A,...

Gallus gallus

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Disease relevance of CYP1A1

  • A truncated construct of the turkey CYP1A5 gene with 29 amino acids deleted from the hydrophobic NH2-terminal region was cloned and heterologously expressed in Escherichia coli [1].

High impact information on CYP1A1

  • Induction of tamoxifen-4-hydroxylation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), beta-naphthoflavone (beta NF), and phenobarbital (PB) in avian liver: identification of P450 TCDDAA as catalyst of 4-hydroxylation induced by TCDD and beta NF [2].
  • Northern analysis shows that the chick enzymes have a different tissue distribution from CYP1A1 and -1A2 [3].
  • Amino acid sequence analysis shows that although each chick enzyme can be classified in the CYP1A family, both are more like CYP1A1 than -1A2, and neither can be said to be directly orthologous to CYP1A1 or -1A2 [3].
  • The P-450s exhibit catalytic selectivity either for arachidonic acid metabolism, particularly epoxygenation (P-450 TCDDAA, 55 kDa), or for aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin deethylase (7-EROD) (P-450 TCDDAHH, 54.5 kDa) [4].
  • Spatial heterogeneity in phylogenetic signal along the sequences strongly indicated that cormorant CYP1A4 and CYP1A5 have undergone partial interparalog gene conversion, similar to chicken and mammalian CYP1As [5].

Biological context of CYP1A1

  • Phylogenetic analysis of complete coding sequences suggests that mammalian and bird paralog pairs (CYP1A1/2 and CYP1A4/5, respectively) are the result of independent gene duplication events [6].
  • Together, these data indicate that avian and mammalian CYP1A paralog pairs resulted from a single gene duplication event and that extensive gene conversion is responsible for the exceptionally high degree of sequence similarity between CYP1A4 and CYP1A5 [6].
  • Basal and TCB-inducible CYP1A5 mRNA expression was maximal in liver at 8 days of development and remained high throughout the remainder of embryonic development [7].
  • Hepatic CYP1A4 and CYP1A5 mRNA levels in wild cormorants from Lake Biwa, Japan, were quantified to examine the effects of DRCs on isoform-specific expression and to evaluate the toxicokinetics of DRCs in which CYP1A expression is involved [5].
  • A partial gene sequence for CYP1A5 indicated that the intron/exon organization of this gene was identical to that of the CYP1A1 and CYP1A2 mammalian genes and was present in a single copy in the genome [7].

Anatomical context of CYP1A1


Associations of CYP1A1 with chemical compounds


Regulatory relationships of CYP1A1


Other interactions of CYP1A1

  • Ah receptor activation leads to the induction of cytochrome P450 (CYP) 1A enzymes, which include CYP1A1 and 1A2 in mammals and CYP1A4 and 1A5 in chickens [9].

Analytical, diagnostic and therapeutic context of CYP1A1

  • On Western blots non-immunopurified anti-TCDDAA and anti-TCDDAHH antisera recognized rat and guinea pig CYP1A1 and CYP1A2 [4].
  • Phylogenetic analysis shows that the two chick enzymes form a separate branch in the CYP1A family tree distinct from mammalian CYP1A1 and -1A2 and from fish CYP1A enzymes [3].
  • JC CYP1A5 mRNA expression measured by real-time RT-PCR had a significant positive correlation with hepatic TEQs, suggesting induction of CYP1A5 at the transcriptional level [14].


  1. Molecular cloning and expression of a novel cytochrome p450 from turkey liver with aflatoxin b1 oxidizing activity. Yip, S.S., Coulombe, R.A. Chem. Res. Toxicol. (2006) [Pubmed]
  2. Induction of tamoxifen-4-hydroxylation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), beta-naphthoflavone (beta NF), and phenobarbital (PB) in avian liver: identification of P450 TCDDAA as catalyst of 4-hydroxylation induced by TCDD and beta NF. Kupfer, D., Mani, C., Lee, C.A., Rifkind, A.B. Cancer Res. (1994) [Pubmed]
  3. Molecular cloning and expression of two novel avian cytochrome P450 1A enzymes induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Gilday, D., Gannon, M., Yutzey, K., Bader, D., Rifkind, A.B. J. Biol. Chem. (1996) [Pubmed]
  4. Purification and biochemical characterization of two major cytochrome P-450 isoforms induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in chick embryo liver. Rifkind, A.B., Kanetoshi, A., Orlinick, J., Capdevila, J.H., Lee, C. J. Biol. Chem. (1994) [Pubmed]
  5. Cytochrome P450 1A4 and 1A5 in common cormorant (Phalacrocorax carbo): evolutionary relationships and functional implications associated with dioxin and related compounds. Kubota, A., Iwata, H., Goldstone, H.M., Kim, E.Y., Stegeman, J.J., Tanabe, S. Toxicol. Sci. (2006) [Pubmed]
  6. A revised evolutionary history of the CYP1A subfamily: gene duplication, gene conversion, and positive selection. Goldstone, H.M., Stegeman, J.J. J. Mol. Evol. (2006) [Pubmed]
  7. Developmental regulation of the 3-methylcholanthrene- and dioxin-inducible CYP1A5 gene in chick embryo liver in vivo. Bentivegna, C.S., Ihnat, M.A., Baptiste, N.S., Hamilton, J.W. Toxicol. Appl. Pharmacol. (1998) [Pubmed]
  8. TCDD induces CYP1A4 and CYP1A5 in chick liver and kidney and only CYP1A4, an enzyme lacking arachidonic acid epoxygenase activity, in myocardium and vascular endothelium. Gannon, M., Gilday, D., Rifkind, A.B. Toxicol. Appl. Pharmacol. (2000) [Pubmed]
  9. Transcriptional activation of avian CYP1A4 and CYP1A5 by 2,3,7, 8-tetrachlorodibenzo-p-dioxin: differences in gene expression and regulation compared to mammalian CYP1A1 and CYP1A2. Mahajan, S.S., Rifkind, A.B. Toxicol. Appl. Pharmacol. (1999) [Pubmed]
  10. Catalytic and immunochemical properties of hepatic cytochrome P450 1A in three avian species treated with beta-naphthoflavone or isosafrole. Verbrugge, L.A., Giesy, J.P., Verbrugge, D.A., Woodin, B.R., Stegeman, J.J. Comp. Biochem. Physiol. C Toxicol. Pharmacol. (2001) [Pubmed]
  11. Same-sample analysis of ethoxyresorufin-O-deethylase activity and cytochrome P4501A mRNA abundance in chicken embryo hepatocytes. Head, J.A., Kennedy, S.W. Anal. Biochem. (2007) [Pubmed]
  12. Identification of CYP1A5 as the CYP1A enzyme mainly responsible for uroporphyrinogen oxidation induced by AH receptor ligands in chicken liver and kidney. Sinclair, P.R., Gorman, N., Walton, H.S., Sinclair, J.F., Lee, C.A., Rifkind, A.B. Drug Metab. Dispos. (1997) [Pubmed]
  13. Effect of arsenite on the induction of CYP1A4 and CYP1A5 in cultured chick embryo hepatocytes. Jacobs, J.M., Nichols, C., Marek, D., Gorman, N., Walton, H.S., Sinclair, P.R., Sinclair, J.F. Toxicol. Appl. Pharmacol. (2000) [Pubmed]
  14. Induction of cytochrome P450 1A5 mRNA, protein and enzymatic activities by dioxin-like compounds, and congener-specific metabolism and sequestration in the liver of wild jungle crow (Corvus macrorhynchos) from Tokyo, Japan. Watanabe, M.X., Iwata, H., Okamoto, M., Kim, E.Y., Yoneda, K., Hashimoto, T., Tanabe, S. Toxicol. Sci. (2005) [Pubmed]
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