Expression of CYP2A genes in human liver and extrahepatic tissues

Biochem Pharmacol. 1999 Jun 15;57(12):1407-13. doi: 10.1016/s0006-2952(99)00015-5.


Members of the human cytochrome P450 2A (CYP2A) subfamily are known to metabolize several promutagens, procarcinogens, and pharmaceuticals. In this study, the expression of the three genes found in the human CYP2A gene cluster was investigated in the liver and several extrahepatic tissues by gene-specific reverse transcriptase-polymerase chain reaction (RT-PCR). All three transcripts (CYP2A6, CYP2A7, and CYP2A13) were found to be present in liver. Quantitative RT-PCR analysis showed that CYP2A6 and CYP2A7 mRNAs were present at roughly equal levels in the liver, while CYP2A13 was expressed at very low levels. Two putative splicing variants of CYP2A7 were found in the liver. Nasal mucosa contained a low level of CYP2A6 and a relatively high level of CYP2A13 transcripts. Kidney, duodenum, lung, alveolar macrophages, peripheral lymphocytes, placenta, and uterine endometrium were negative for all transcripts. This survey gives a comprehensive picture of the expression pattern of CYP2A genes in liver and extrahepatic tissues and constitutes a basis for a search for functional CYP2A forms and their roles in chemical toxicity in liver and nasal mucosa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aryl Hydrocarbon Hydroxylases*
  • Cytochrome P-450 Enzyme System / biosynthesis
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P450 Family 2
  • Databases, Factual
  • Expressed Sequence Tags
  • Humans
  • Liver / enzymology*
  • Liver / metabolism
  • Nasal Mucosa / enzymology
  • Nasal Mucosa / metabolism
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Steroid Hydroxylases / biosynthesis
  • Steroid Hydroxylases / genetics*


  • RNA, Messenger
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • Aryl Hydrocarbon Hydroxylases
  • CYP2A7 protein, human
  • Cytochrome P450 Family 2
  • steroid hormone 6-beta-hydroxylase