PROSITE documentation PDOC00519
Aminotransferases class-III pyridoxal-phosphate attachment site


Aminotransferases share certain mechanistic features with other pyridoxal-phosphate dependent enzymes, such as the covalent binding of the pyridoxal-phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped [1,2] into subfamilies. One of these, called class-III, currently consists of the following enzymes:

  • Acetylornithine aminotransferase (EC which catalyzes the transfer of an amino group from acetylornithine to α-ketoglutarate, yielding N-acetyl-glutamic-5-semi-aldehyde and glutamic acid.
  • Ornithine aminotransferase (EC, which catalyzes the transfer of an amino group from ornithine to α-ketoglutarate, yielding glutamic-5- semi-aldehyde and glutamic acid.
  • Omega-amino acid--pyruvate aminotransferase (EC, which catalyzes transamination between a variety of omega-amino acids, mono- and diamines, and pyruvate. It plays a pivotal role in omega amino acids metabolism.
  • 4-aminobutyrate aminotransferase (EC (GABA transaminase), which catalyzes the transfer of an amino group from GABA to α-ketoglutarate, yielding succinate semialdehyde and glutamic acid.
  • DAPA aminotransferase (EC, a bacterial enzyme (gene bioA) which catalyzes an intermediate step in the biosynthesis of biotin, the transamination of 7-keto-8-aminopelargonic acid (7-KAP) to form 7,8- diaminopelargonic acid (DAPA).
  • 2,2-dialkylglycine decarboxylase (EC, a Pseudomonas cepacia enzyme (gene dgdA) that catalyzes the decarboxylating amino transfer of 2,2-dialkylglycine and pyruvate to dialkyl ketone, alanine and carbon dioxide.
  • Glutamate-1-semialdehyde aminotransferase (EC (GSA). GSA is the enzyme involved in the second step of porphyrin biosynthesis, via the C5 pathway. It transfers the amino group on carbon 2 of glutamate-1- semialdehyde to the neighbouring carbon, to give delta-aminolevulinic acid.
  • Bacillus subtilis aminotransferase yhxA.
  • Bacillus subtilis aminotransferase yodT.
  • Haemophilus influenzae aminotransferase HI0949.
  • Caenorhabditis elegans aminotransferase T01B11.2.

The sequence around the pyridoxal-phosphate attachment site of this class of enzyme is sufficiently conserved to allow the creation of a specific pattern.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

AA_TRANSFER_CLASS_3, PS00600; Aminotransferases class-III pyridoxal-phosphate attachment site  (PATTERN)


1AuthorsBairoch A.
SourceUnpublished observations (1992).

2AuthorsYonaha K. Nishie M. Aibara S.
SourceJ. Biol. Chem. 267:12506-12510(1992).

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