LAP3 also known as cytosol aminopeptidase. LAP3 presumably involved in the processing and regular turnover of intracellular proteins. This protein catalyzes the removal of unsubstituted N-terminal amino acids from various peptides. It 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, and Yaa may be Pro. Amino acid amides and methyl esters are also readily hydrolyzed, but rates on arylamides are exceedingly low. Recombinant human LAP3, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.