Carboxypeptidase that may play an important role in the hydrolysis of circulating peptides. Catalyzes the hydrolysis of dipeptides with unsubstituted terminals into amino acids. May play a role in the liberation of thyroxine hormone from its thyroglobulin (Tg) precursor. Homodimer. The monomeric form is inactive while the homodimer is active (By similarity). Secretion is stimulated by TSH/thyroid-stimulating hormone, INS/insulin and SST/somatostatin. During regeneration of liver. N-glycosylated. The secreted form is modified by hybrid or complex type oligosaccharide chains. Belongs to the peptidase M28 family.