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 (By similarity). 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. N-glycosylated. The secreted form is modified by hybrid or complex type oligosaccharide chains. Belongs to the peptidase M28 family. Aberrant splicing.