Catalyzes the removal of a penultimate prolyl residue from the N-termini of peptides, such as Arg-Pro-Pro (By similarity). Aminopeptidase that binds to the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). May play a negative role in the regulation of PIN auxin transport proteins (PubMed:11891249). Release of any N-terminal amino acid, including proline, that is linked to proline, even from a dipeptide or tripeptide. Binds 2 manganese or zinc ions per subunit. Inhibited by EGTA and apstatin, and, to some extent, by the flavonoid kaempferol. Homodimer (By similarity). Interacts with N-1-naphthylphthalamic acid (NPA) (PubMed:11891249). Ubiquitous with preferential expression in 5 days-old seedlings, roots, flowers, inflorescences and rosette leaves (at protein levels). Expression starts at 3 days and peaks at 5 days. After, expression levels remain constant from 7 to 10 days. Glycosylated. Also present in a non-glycosylated form. Belongs to the peptidase M24B family.