PROSITE documentation PDOC00548
Cytosol aminopeptidase signature


Cytosol aminopeptidase is a eukaryotic cytosolic zinc-dependent exopeptidase that catalyzes the removal of unsubstituted amino-acid residues from the N-terminus of proteins. This enzyme is often known as leucine aminopeptidase (EC (LAP) but has been shown [1] to be identical with prolyl aminopeptidase (EC Cytosol aminopeptidase is a hexamer of identical chains, each of which binds two zinc ions.

Cytosol aminopeptidase is highly similar to Escherichia coli pepA, a manganese dependent aminopeptidase. Residues involved in zinc ion-binding [2] in the mammalian enzyme are absolutely conserved in pepA where they presumably bind manganese. Most bacterial species contain a pepA-type enzyme.

As a signature pattern for these enzymes, we selected a perfectly conserved octapeptide which contains two residues involved in binding metal ions: an aspartate and a glutamate.


These proteins belong to family M17 in the classification of peptidases [3,E1].

Last update:

April 2006 / Pattern revised.


Technical section

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

CYTOSOL_AP, PS00631; Cytosol aminopeptidase signature  (PATTERN)


1AuthorsMatsushima M. Takahashi T. Ichinose M. Miki K. Kurokawa K. Takahashi K.
TitleStructural and immunological evidence for the identity of prolyl aminopeptidase with leucyl aminopeptidase.
SourceBiochem. Biophys. Res. Commun. 178:1459-1464(1991).
PubMed ID1908238

2AuthorsBurley S.K. David P.R. Sweet R.M. Taylor A. Lipscomb W.N.
TitleStructure determination and refinement of bovine lens leucine aminopeptidase and its complex with bestatin.
SourceJ. Mol. Biol. 224:113-140(1992).
PubMed ID1548695

3AuthorsRawlings N.D. Barrett A.J.
TitleEvolutionary families of metallopeptidases.
SourceMethods Enzymol. 248:183-228(1995).
PubMed ID7674922


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