Specifically removes C-terminal basic residues (Arg or Lys) from peptides and proteins. It is believed to play important roles in the control of peptide hormone and growth factor activity at the cell surface, and in the membrane-localized degradation of extracellular proteins. Cleavage of C-terminal arginine or lysine residues from polypeptides. Binds 1 zinc ion per subunit. Inhibited by O-phenanthroline and MGTA and activated by cobalt. Optimum pH is 7.0. Belongs to the peptidase M14 family.