Flavin-containing monooxygenase isoform 2: developmental expression in fetal and neonatal rabbit lung

J Biochem Mol Toxicol. 1999;13(3-4):187-93. doi: 10.1002/(sici)1099-0461(1999)13:3/4<187::aid-jbt9>3.0.co;2-6.


Mammalian flavin-containing monooxygenase functions in the oxygenation of numerous xenobiotics containing a soft nucleophile, usually a nitrogen or sulfur. A total of five distinct flavin monooxygenase (FMO) isoforms are expressed in mammals. Individual isoforms are expressed in a sex-, age-, and tissue-specific fashion. In this study, we document the early developmental appearance of the major isoform in rabbit lung, FMO2. FMO2 catalytic activity as well as protein and mRNA are not only present in fetal and neonatal lung but, in some instances, approach levels found in the adult. The expression pattern of FMO2 is similar to that of the two major constitutive cytochromes P450 found in rabbit lung, 2B4 and 4B1. The early developmental appearance of these monooxygenases indicate an important role in the protection of the fetus and neonate against toxic insult from foreign chemicals.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Aryl Hydrocarbon Hydroxylases*
  • Catalysis
  • Cytochrome P-450 Enzyme System / metabolism
  • Female
  • Gene Expression Regulation, Developmental*
  • Gene Expression Regulation, Enzymologic*
  • Isoenzymes / genetics*
  • Lung / embryology
  • Lung / enzymology*
  • Lung / growth & development
  • Oxygenases / genetics*
  • Oxygenases / metabolism
  • Pregnancy
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rabbits
  • Steroid Hydroxylases / metabolism


  • Isoenzymes
  • RNA, Messenger
  • Cytochrome P-450 Enzyme System
  • Oxygenases
  • Steroid Hydroxylases
  • dimethylaniline monooxygenase (N-oxide forming)
  • Aryl Hydrocarbon Hydroxylases
  • cytochrome P-450 CYP4B1
  • steroid 15-alpha-hydroxylase