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Protein CYP1A2 PDB 2hi4.png
Available structures
PDBOrtholog search: PDBe RCSB
AliasesCYP1A2, CP12, P3-450, P450(PA), cytochrome P450 family 1 subfamily A member 2, Cytochrome P450 1A2, CYPIA2
External IDsOMIM: 124060 MGI: 88589 HomoloGene: 68082 GeneCards: CYP1A2
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 15: 74.75 – 74.76 MbChr 9: 57.58 – 57.59 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

Cytochrome P450 1A2 (abbreviated CYP1A2), a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the human body.[5] In humans, the CYP1A2 enzyme is encoded by the CYP1A2 gene.[6]


CYP1A2 is a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP1A2 localizes to the endoplasmic reticulum and its expression is induced by some polycyclic aromatic hydrocarbons (PAHs), some of which are found in cigarette smoke. The enzyme's endogenous substrate is unknown; however, it is able to metabolize some PAHs to carcinogenic intermediates. Other xenobiotic substrates for this enzyme include caffeine, aflatoxin B1, and paracetamol (acetaminophen). The transcript from this gene contains four Alu sequences flanked by direct repeats in the 3' untranslated region.[7]

CYP1A2 also metabolizes polyunsaturated fatty acids into signaling molecules that have physiological as well as pathological activities. It has monoxygenase activity for certain of these fatty acids in that it metabolizes arachidonic acid to 19-hydroxyeicosatetraenoic acid (19-HETE) (see 20-Hydroxyeicosatetraenoic acid) but also has epoxygenase activity in that it metabolizes docosahexaenoic acid to epoxides, primarily 19R,20S-epoxyeicosapentaenoic acid and 19S,20R-epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and similarly metabolizes eicosapentaenoic acid to epoxides, primarily 17R,18S-eicosatetraenoic acid and 17S,18R-eicosatetraenoic acid isomers (termed 17,18-EEQ).[8]

19-HETE is an inhibitor of 20-HETE, a broadly active signaling molecule, e.g. it constricts arterioles, elevates blood pressure, promotes inflammation responses, and stimulates the growth of various types of tumor cells; however the in vivo ability and significance of 19-HETE in inhibiting 20-HETE has not been demonstrated (see 20-Hydroxyeicosatetraenoic acid). The EDP (see Epoxydocosapentaenoic acid) and EEQ (see epoxyeicosatetraenoic acid) metabolites have a broad range of activities. In various animal models and in vitro studies on animal and human tissues, they decrease hypertension and pain perception; suppress inflammation; inhibit angiogenesis, endothelial cell migration and endothelial cell proliferation; and inhibit the growth and metastasis of human breast and prostate cancer cell lines.[9][10][11][12] It is suggested that the EDP and EEQ metabolites function in humans as they do in animal models and that, as products of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid, the EDP and EEQ metabolites contribute to many of the beneficial effects attributed to dietary omega-3 fatty acids.[9][12][13] EDP and EEQ metabolites are short-lived, being inactivated within seconds or minutes of formation by epoxide hydrolases, particularly soluble epoxide hydrolase, and therefore act locally.

CYP1A2 is not regarded as being a major contributor to forming the cited epoxides[12] but could act locally in certain tissues to do so.

The authoratitive list of star allele nomenclature for CYP1A2 along with activity scores is kept by PharmVar[14]

Effect of diet[edit]

Expression of CYP1A2 appears to be induced by various dietary constituents.[15] Vegetables such as cabbages, cauliflower and broccoli are known to increase levels of CYP1A2. Lower activity of CYP1A2 in South Asians appears to be due to cooking these vegetables in curries using ingredients such as cumin and turmeric, ingredients known to inhibit the enzyme.[16]

CYP1A2 is also involved in the metabolization of caffeine, and the presence of alleles that make this metabolization slow have been associated with an increased risk of nonfatal myocardial infarction for those who drink a lot of coffee (4 per day and up).[17]


Following is a table of selected substrates, inducers and inhibitors of CYP1A2.

Inhibitors of CYP1A2 can be classified by their potency, such as:

  • Strong inhibitor being one that causes at least a 5-fold increase in the plasma AUC values of sensitive substrates metabolized through CYP1A2, or more than 80% decrease in clearance thereof.[18]
  • Moderate inhibitor being one that causes at least a 2-fold increase in the plasma AUC values of sensitive substrates metabolized through CYP1A2, or 50-80% decrease in clearance thereof.[18]
  • Weak inhibitor being one that causes at least a 1.25-fold but less than 2-fold increase in the plasma AUC values of sensitive substrates metabolized through CYP1A2, or 20-50% decrease in clearance thereof.[18]
Substrates Inhibitors Inducers



Unspecified potency:

Moderate inducers:[20]

Unspecified potency:

See also[edit]


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000140505 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000032310 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Nelson DR, Zeldin DC, Hoffman SM, Maltais LJ, Wain HM, Nebert DW (Jan 2004). "Comparison of cytochrome P450 (CYP) genes from the mouse and human genomes, including nomenclature recommendations for genes, pseudogenes and alternative-splice variants". Pharmacogenetics. 14 (1): 1–18. doi:10.1097/00008571-200401000-00001. PMID 15128046. S2CID 18448751.
  6. ^ Jaiswal AK, Nebert DW, McBride OW, Gonzalez FJ (1987). "Human P(3)450: cDNA and complete protein sequence, repetitive Alu sequences in the 3' nontranslated region, and localization of gene to chromosome 15". Journal of Experimental Pathology. 3 (1): 1–17. PMID 3681487.
  7. ^ "Entrez Gene: cytochrome P450".
  8. ^ Westphal C, Konkel A, Schunck WH (Nov 2011). "CYP-eicosanoids--a new link between omega-3 fatty acids and cardiac disease?". Prostaglandins & Other Lipid Mediators. 96 (1–4): 99–108. doi:10.1016/j.prostaglandins.2011.09.001. PMID 21945326.
  9. ^ a b Fleming I (Oct 2014). "The pharmacology of the cytochrome P450 epoxygenase/soluble epoxide hydrolase axis in the vasculature and cardiovascular disease". Pharmacological Reviews. 66 (4): 1106–40. doi:10.1124/pr.113.007781. PMID 25244930.
  10. ^ Zhang G, Kodani S, Hammock BD (Jan 2014). "Stabilized epoxygenated fatty acids regulate inflammation, pain, angiogenesis and cancer". Progress in Lipid Research. 53: 108–23. doi:10.1016/j.plipres.2013.11.003. PMC 3914417. PMID 24345640.
  11. ^ He J, Wang C, Zhu Y, Ai D (Dec 2015). "Soluble epoxide hydrolase: A potential target for metabolic diseases". Journal of Diabetes. 8 (3): 305–13. doi:10.1111/1753-0407.12358. PMID 26621325.
  12. ^ a b c Wagner K, Vito S, Inceoglu B, Hammock BD (Oct 2014). "The role of long chain fatty acids and their epoxide metabolites in nociceptive signaling". Prostaglandins & Other Lipid Mediators. 113–115: 2–12. doi:10.1016/j.prostaglandins.2014.09.001. PMC 4254344. PMID 25240260.
  13. ^ Fischer R, Konkel A, Mehling H, Blossey K, Gapelyuk A, Wessel N, von Schacky C, Dechend R, Muller DN, Rothe M, Luft FC, Weylandt K, Schunck WH (Mar 2014). "Dietary omega-3 fatty acids modulate the eicosanoid profile in man primarily via the CYP-epoxygenase pathway". Journal of Lipid Research. 55 (6): 1150–1164. doi:10.1194/jlr.M047357. PMC 4031946. PMID 24634501.
  14. ^ "PharmVar". PharmVar. Retrieved 20 May 2020.
  15. ^ Fontana RJ, Lown KS, Paine MF, Fortlage L, Santella RM, Felton JS, Knize MG, Greenberg A, Watkins PB (Jul 1999). "Effects of a chargrilled meat diet on expression of CYP3A, CYP1A, and P-glycoprotein levels in healthy volunteers". Gastroenterology. 117 (1): 89–98. doi:10.1016/S0016-5085(99)70554-8. PMID 10381914.
  16. ^ a b c d e Sanday, Kate (17 October 2011), "South Asians and Europeans react differently to common drugs", University of Sydney Faculty of Pharmacy News
  17. ^ Cornelis MC, El-Sohemy A, Kabagambe EK, Campos H (2006-03-08). "Coffee, CYP1A2 genotype, and risk of myocardial infarction". JAMA. 295 (10): 1135–1141. doi:10.1001/jama.295.10.1135. ISSN 1538-3598. PMID 16522833.
  18. ^ a b c Center for Drug Evaluation and Research. "Drug Interactions & Labeling - Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers". Retrieved 2016-06-01.
  19. ^ a b c d Sousa MC, Braga RC, Cintra BA, de Oliveira V, Andrade CH (2013). "In silico metabolism studies of dietary flavonoids by CYP1A2 and CYP2C9". Food Research International. 50: 102–110. doi:10.1016/j.foodres.2012.09.027.
  20. ^ a b c d e f g h i j k l m n o p q r s t u v "Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers". FDA. 26 May 2021.
  21. ^ Alkattan, A., & Alsalameen, E. (2021). Polymorphisms of genes related to phase-I metabolic enzymes affecting the clinical efficacy and safety of clopidogrel treatment. Expert opinion on drug metabolism & toxicology, 10.1080/17425255.2021.1925249. Advance online publication.
  22. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap Flockhart DA (2007). "Drug Interactions Flockhart Table". Indiana University School of Medicine.
  23. ^ a b c d e f g h i j k l m n o p Swedish environmental classification of pharmaceuticals - FASS (drug catalog) - Facts for prescribers (Fakta för förskrivare). Retrieved July 2011
  24. ^ Savage RA, Zafar N, Yohannan S, Miller JM (2021). "article-35398". Melatonin. Treasure Island (FL): StatPearls Publishing. PMID 30521244. Retrieved 2021-11-15. Ninety percent of melatonin is metabolized in the liver primarily by the enzyme CYP1A2
  25. ^ "Erlotinib". Metabolized primarily by CYP3A4 and, to a lesser degree, by CYP1A2 and the extrahepatic isoform CYP1A1
  26. ^ a b "Verapamil: Drug information. Lexicomp". UpToDate. Retrieved 2019-01-13. Metabolism/Transport Effects: Substrate of CYP1A2 (minor), CYP2B6 (minor), CYP2C9 (minor), CYP2E1 (minor), CYP3A4 (major), P-glycoprotein/ABCB1; Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP1A2 (weak), CYP3A4 (moderate), P-glycoprotein/ABCB1
  27. ^ Dostalek M, Pistovcakova J, Jurica J, Sulcová A, Tomandl J (Sep 2011). "The effect of St John's wort (hypericum perforatum) on cytochrome p450 1a2 activity in perfused rat liver". Biomedical Papers of the Medical Faculty of the University Palacký, Olomouc, Czechoslovakia. 155 (3): 253–7. doi:10.5507/bp.2011.047. PMID 22286810.
  28. ^ "Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers". U.S. Food and Drug Administration. 2019-02-09.
  29. ^ Gorski JC, Huang SM, Pinto A, Hamman MA, Hilligoss JK, Zaheer NA, Desai M, Miller M, Hall SD (Jan 2004). "The effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo". Clinical Pharmacology and Therapeutics. 75 (1): 89–100. doi:10.1016/j.clpt.2003.09.013. PMID 14749695. S2CID 8375888.
  30. ^ a b c Briguglio M, Hrelia S, Malaguti M, Serpe L, Canaparo R, Dell'Osso B, et al. (December 2018). "Food Bioactive Compounds and Their Interference in Drug Pharmacokinetic/Pharmacodynamic Profiles". Pharmaceutics. 10 (4): 277. doi:10.3390/pharmaceutics10040277. PMC 6321138. PMID 30558213.
  31. ^ Fuhr U, Klittich K, Staib AH (Apr 1993). "Inhibitory effect of grapefruit juice and its bitter principal, naringenin, on CYP1A2 dependent metabolism of caffeine in man". British Journal of Clinical Pharmacology. 35 (4): 431–6. doi:10.1111/j.1365-2125.1993.tb04162.x. PMC 1381556. PMID 8485024.
  32. ^ Wen X, Wang JS, Neuvonen PJ, Backman JT (Jan 2002). "Isoniazid is a mechanism-based inhibitor of cytochrome P450 1A2, 2A6, 2C19 and 3A4 isoforms in human liver microsomes". Eur J Clin Pharmacol. 57 (11): 799–804. doi:10.1007/s00228-001-0396-3. PMID 11868802. S2CID 19299097.
  33. ^ Zhao Y, Hellum BH, Liang A, Nilsen OG (June 2015). "Inhibitory Mechanisms of Human CYPs by Three Alkaloids Isolated from Traditional Chinese Herbs". Phytotherapy Research. 29 (6): 825–34. doi:10.1002/ptr.5285. PMID 25640685. S2CID 24002845.

Further reading[edit]

External links[edit]

This article incorporates text from the United States National Library of Medicine, which is in the public domain.