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PROSITE documentation PDOC00098 [for PROSITE entry PS00105]

Aminotransferases class-I 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-I, currently consists of the following enzymes:

  • Aspartate aminotransferase (AAT) (EC AAT catalyzes the reversible transfer of the amino group from L-aspartate to 2-oxoglutarate to form oxaloacetate and L-glutamate. In eukaryotes, there are two AAT isozymes: one is located in the mitochondrial matrix, the second is cytoplasmic. In prokaryotes, only one form of AAT is found (gene aspC).
  • Tyrosine aminotransferase (EC which catalyzes the first step in tyrosine catabolism by reversibly transferring its amino group to 2- oxoglutarate to form 4-hydroxyphenylpyruvate and L-glutamate.
  • Aromatic aminotransferase (EC involved in the synthesis of Phe, Tyr, Asp and Leu (gene tyrB).
  • 1-aminocyclopropane-1-carboxylate synthase (EC (ACC synthase) from plants. ACC synthase catalyzes the first step in ethylene biosynthesis.
  • Pseudomonas denitrificans cobC, which is involved in cobalamin biosynthesis.
  • Yeast hypothetical protein YJL060w.

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:

April 2006 / Pattern revised.

Technical section

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

AA_TRANSFER_CLASS_1, PS00105; Aminotransferases class-I pyridoxal-phosphate attachment site  (PATTERN)


1AuthorsBairoch A.
SourceUnpublished observations (1992).

2AuthorsSung M.H. Tanizawa K. Tanaka H. Kuramitsu S. Kagamiyama H. Hirotsu K. Okamoto A. Higuchi T. Soda K.
TitleThermostable aspartate aminotransferase from a thermophilic Bacillus species. Gene cloning, sequence determination, and preliminary x-ray characterization.
SourceJ. Biol. Chem. 266:2567-2572(1991).
PubMed ID1990006

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