Primary structure and molecular basis of polymorphic appearance of an acetyltransferase (AT-II)* in hamsters

Pharmacogenetics. 1994 Apr;4(2):91-100. doi: 10.1097/00008571-199404000-00006.


Three hamster clones (clones 1, 2 and 3) were isolated from a genomic library constructed from a homozygote rapid acetylator using a cDNA (hamAT-101) of a monomorphic acetyltransferase (AT-I) as a probe. Clone 1 (13 kbp) was found to contain a gene corresponding to AT-I. The entire coding region was located in an exon and completely identical to that of AT-I cDNA. Clones 2 and 3 (14.5 and 15 kbp) each contained identical information to the AT-I-related protein (AT-B protein). The intronless coding region shared 83.7% of sequence similarly to the AT-I cDNA, and its length was identical to that of the AT-I cDNA. Clone 2 also included a nucleotide sequence identical to the 3'-portion of the AT-I gene, which is located 5'-upstream of the AT-B gene. Restricted fragment lengths of clone 3, which encompassed the entire coding region was expressed in COS-1 cells. The expressed protein migrated at a position identical to that of AT-II purified from a hamster liver on Western blots. AT-B-expressed protein catalysed acetyl CoA-dependent N-acetylation of 2-aminofluorene and p-aminobenzoic acid, but had marginal activities for O-acetylation of 2-N-hydroxyamino-6-methyl-6-methyldipyrido[1,2-a:3',2'-d]imidazole and N-hydroxyarylacetamide-dependent N-acetylation of 4-aminoazobenzene. These results are in good agreement with the data of AT-II purified from hamster livers, indicating that the AT-B gene encodes a polymorphic acetyltransferase (AT-II) in hamsters. Although the AT-II protein was undetectable in slow acetylators, specific mRNA, hybridizing with a selective oligonucleotide probe for the AT-II gene (AT-B), was detected in livers of both homozygous acetylators. Analysis of genomic DNA of a homozygous slow phenotype hamster indicates that AT-II DNA from the slow phenotype has a point mutation which causes premature termination at the 243th (Arg to stop codon) position of the deduced amino acid sequence. PCR-RFLP analysis further confirmed that the point mutation conferred a defective AT-II protein in slow phenotype hamsters.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Aminobenzoic Acid
  • Acetylation
  • Amino Acid Sequence
  • Animals
  • Arylamine N-Acetyltransferase / genetics*
  • Base Sequence
  • Cloning, Molecular
  • Cricetinae
  • Fluorenes / metabolism
  • Genomic Library
  • Isoenzymes / genetics*
  • Liver / enzymology
  • Mesocricetus / genetics*
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • Polymorphism, Restriction Fragment Length
  • RNA, Messenger / analysis
  • Recombinant Proteins / biosynthesis
  • Sequence Homology, Nucleic Acid
  • Species Specificity
  • Substrate Specificity


  • Fluorenes
  • Isoenzymes
  • RNA, Messenger
  • Recombinant Proteins
  • 2-aminofluorene
  • AT-I acetyltransferase
  • AT-II acetyltransferase
  • Arylamine N-Acetyltransferase
  • 4-Aminobenzoic Acid

Associated data

  • GENBANK/S72004
  • GENBANK/S72005
  • GENBANK/S72007