InterPro domain: IPR001948

This group of metallopeptidases belong to the MEROPS peptidase family M18, (clan MH). The proteins have two catalytic zinc ions at the active site, bound by His/Asp, Asp, Glu, Asp/Glu and His. The catalysed reaction involves the release of an N-terminal aminoacid, usually neutral or hydrophobic, from a polypeptide [ 1 ].

The type example is aminopeptidase I from Saccharomyces cerevisiae (Baker's yeast), the sequence of which has been deduced, and the mature protein shown to consistof 469 amino acids [ 2 ]. A 45-residue presequence contains bothpositively- and negatively-charged and hydrophobic residues, which could be arrangedin an N-terminal amphiphilic alpha-helix [ 3 ]. The presequence differs fromsignal sequences that direct proteins across bacterial plasma membranes andendoplasmic reticulum or into mitochondria. It is unclear how this uniquepresequence targets aminopeptidase I to yeast vacuoles, and how thissorting utilises classical protein secretory pathways [ 3 ].

1. Evolutionary families of metallopeptidases. Meth. Enzymol. 248, 183-228
2. Molecular cloning and sequencing of genomic DNA encoding aminopeptidase I from Saccharomyces cerevisiae. J. Biol. Chem. 264, 6979-83