PROSITE documentation PDOC00514
Aminotransferases class-V 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-V, currently consists of the following enzymes:

  • Phosphoserine aminotransferase (EC, an enzyme which catalyzes the reversible interconversion of phosphoserine and 2-oxoglutarate to 3-phosphonooxypyruvate and glutamate. It is required both in the major phosphorylated pathway of serine biosynthesis and in pyridoxine biosynthesis. The bacterial enzyme (gene serC) is highly similar to a rabbit endometrial progesterone-induced protein (EPIP), which is probably a phosphoserine aminotransferase [3].
  • Serine--glyoxylate aminotransferase (EC (SGAT) (gene sgaA) from Methylobacterium extorquens.
  • Serine--pyruvate aminotransferase (EC This enzyme also acts as an alanine--glyoxylate aminotransferase (EC In vertebrates, it is located in the peroxisomes and/or mitochondria.
  • Isopenicillin N epimerase (gene cefD). This enzyme is involved in the biosynthesis of cephalosporin antibiotics and catalyzes the reversible isomerization of isopenicillin N and penicillin N.
  • NifS, a protein of the nitrogen fixation operon of some bacteria and cyanobacteria. The exact function of nifS is not yet known. A highly similar protein has been found in fungi (gene NFS1 or SPL1).
  • The small subunit of cyanobacterial soluble hydrogenase (EC 1.12.-.-).
  • Hypothetical protein ycbU from Bacillus subtilis.
  • Hypothetical protein YFL030w from yeast.

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

Expert(s) to contact by email:

Ouzounis C.

Last update:

November 1997 / Pattern and text revised.


Technical section

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

AA_TRANSFER_CLASS_5, PS00595; Aminotransferases class-V pyridoxal-phosphate attachment site  (PATTERN)


1AuthorsOuzounis C. Sander C.
TitleHomology of the NifS family of proteins to a new class of pyridoxal phosphate-dependent enzymes.
SourceFEBS Lett. 322:159-164(1993).
PubMed ID8482384

2AuthorsBairoch A.
SourceUnpublished observations (1992).

3Authorsvan der Zel A. Lam H.-M. Winkler M.E.
SourceNucleic Acids Res. 17:8379-8379(1989).

PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)