Presumably involved in the processing and regular turnover of intracellular proteins. 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. Release of N-terminal proline from a peptide. Binds 2 Mn(2+) ions per subunit. Homohexamer (dimer of homotrimers). In tubers and floral buds of untreated plants. After abscisic acid (ABA) treatment or mechanical wounding is mostly accumulated in leaves, to a lesser extent in stems, but not in roots. By abscisic acid (ABA), jasmonic acid (JA) and wounding. Belongs to the peptidase M17 family.