cytosol aminopeptidase; leucine aminopeptidase-3; LAP3; proline aminopeptidase; peptidase S (LAP3, LAPEP, PEPS)

Function

• presumably involved in the processing & regular turnover of intracellular proteins
• catalyzes the removal of unsubstituted N-terminal amino acids from various peptides
• removes mostly leucine & other hydrophobic residues
• release of an N-terminal amino acid, Xaa-|-Yaa-, in which Xaa is preferably Leu, but may be other amino acids including pro although not Arg or Lys, & Yaa may be pro
• amino acid amides & methyl esters are also readily hydrolyzed, but rates on arylamides are exceedingly low
• release of N-terminal proline from a peptide

Cofactor:

• binds 2 Zn+2 per subunit
• one Zn+2 ion is tightly bound & essential for enzyme activity; the 2nd metal coordination site can be occupied by Zn+2, Mg+2 or Mn+2 to give enzymes of different activities (putative)

Structure

• homohexamer
• belongs to the peptidase M17 family

Compartment

cytoplasm

Alternative initiation

• named isoforms=2

Expression

• upregulated 3-fold after 14 days of environmental enrichment in mice.

Pathology

• serum levels elevated in hepatobiliary disease
• no elevation of serum levels in bone disease

Notes

initiator methionine is removed

More general terms

• aminopeptidase
• oligomerizing protein

Database

• UniProt: http://www.uniprot.org/uniprot/P28838.html
• OMIM: https://mirror.omim.org/entry/151300