Cleaves substrates with C-terminal arginine residues. Probably modulates the Wnt signaling pathway, by cleaving some undefined protein. May play a role in cleavage during prohormone processing. Inhibited by 2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MGTA) and guanidinoethylmercaptosuccinic acid (GEMSA). Inhibited by chelating agents such as EDTA and EGTA. Optimum pH is 7.8. In placenta, it is present within invasive trophoblasts and in the surrounding extracellular space. Also present in amnion cells, but is not readily apparent in the extracellular matrix of this cell type. Present in normal pituitary gland and neoplastic pituitary gland (especially POMC-, GH- and PRL-producing adenomas) (at protein level). Widely expressed. Belongs to the peptidase M14 family.