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Cloning and functional expression of a soluble form of kynurenine/alpha-aminoadipate aminotransferase from rat kidney.

Authors
  • Buchli, R
  • Alberati-Giani, D
  • Malherbe, P
  • Köhler, C
  • Broger, C
  • Cesura, A M
Type
Published Article
Journal
Journal of Biological Chemistry
Publisher
American Society for Biochemistry & Molecular Biology (ASBMB)
Publication Date
Dec 08, 1995
Volume
270
Issue
49
Pages
29330–29335
Identifiers
PMID: 7493966
Source
Medline
License
Unknown

Abstract

Several aminotransferases with kynurenine aminotransferase (KAT) activity are able to convert L-kynurenine into kynurenic acid, a putative endogenous modulator of glutamatergic neurotransmission. In the rat, one of the described KAT isoforms has been found to correspond to glutamine transaminase K. In addition, rat kidney alpha-aminoadipate aminotransferase (AadAT) also shows KAT activity. In this report, we describe the isolation of a cDNA clone encoding the soluble form of this aminotransferase isoenzyme from rat (KAT/AadAT). Degenerate oligonucleotides were designed from the amino acid sequences of rat kidney KAT/AadAT tryptic peptides for use as primers for reverse transcription-polymerase chain reaction of rat kidney RNA. The resulting polymerase chain reaction fragment was used to screen a rat kidney cDNA library and to isolate a cDNA clone encoding KAT/AadAT. Analysis of the combined DNA sequences indicated the presence of a single 1275-base pair open reading frame coding for a soluble protein of 425 amino acid residues. KAT/AadAT appears to be structurally homologous to aspartate aminotransferase in the pyridoxal 5'-phosphate binding domain. RNA blot analysis of rat tissues, including brain, revealed a single species of KAT/AadAT mRNA of approximately 2.1 kilobases. HEK-293 cells transfected with the KAT/AadAT cDNA exhibited both KAT and AadAT activities with enzymatic properties similar to those reported for the rat native protein.

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