Carboxypeptidase M (CPM) is a 443 amino acid protein belonging to the metallo-carboxypeptidase (metallo-CP) family. Localized to the cell membrane, CPM contains hydrophobic regions in the N and C- termini and has six potential asparagine-linked glycosylation sites. Functionally, CPM specifically removes C-terminal basic amino acids (arginine or lysine) from proteins and polypeptides and is believed to play a role in monocyte to macrophage differentiation. CPM is also thought to play an important role in the control of peptide hormone and growth factor activity at the cell surface, as well as in the membrane-localized degradation of extracellular proteins. Three isoforms of this protein exist as a result of alternative splicing events.