Cell Surface Peptidases

Cells bristle with a battery of surface enzymes, of which the peptidases form the largest and best studied group. These ectopeptidases play crucial roles in many diverse biological functions, including the termination of peptide signals in the nervous system and at peripheral sites. Some of their key physiological roles, such as those of angiotensin- and endothelin-converting enzymes in generating vasoconstrictive agents and endopeptidase-24.11 in activating natriuretic peptides, enkephalins and tachykinins, have made them prime targets for the pharmaceutical industry. Interest among immunologists and haematologists was aroused when several were shown to be identical to cell-surface markers (CD antigens) on human leukocytes. Virologists have been excited to find that some double as receptors for certain viruses.