Carboxypeptidase M (CPM; MEROPS identifier M14.006; ) is an extracellular glycoprotein, bound to cell membranes via a glycosyl-phosphatidylinositol on the C terminus of the protein []. It specifically removes C-terminal basic residues (Arg or Lys) from peptides and proteins [, ]. The highest levels of CPM have been found in human lung and placenta, but significant amounts are present in kidney, blood vessels, intestine, brain, and peripheral nerves. CPM has also been found in soluble form in various body fluids, including amniotic fluid, seminal plasma and urine. Due to its wide distribution in a variety of tissues, it is believed that it plays an important role in the control of peptide hormones and growth factor activity on the cell surface and in the membrane-localized degradation of extracellular proteins. For example, it hydrolyses the C-terminal arginine of epidermal growth factor (EGF) resulting in des-Arg-EGF which binds to the EGF receptor (EGFR) with an equal or greater affinity than native EGF. CPM is a required processing enzyme that generates specific agonists for the B1 receptor [, ].This entry represents the carboxypeptidase (N-terminal) domain of carboxypeptidase M.
