Regulatory peptide metabolism at cell surfaces: the key role of endopeptidase-24.11.

This paper sets out to review some recent work on the role of endopeptidase-24.11. In renal brush borders, this enzyme is usually the only endopeptidase present among a host of exopeptidases, yet it appears to be the rate limiting step in the hydrolysis of a number of peptides, including bradykinin and the angiotensins. Endopeptidase-24.11 is widely, but not ubiquitously distributed--present not only in renal and intestinal brush borders, but also in lymph nodes, glandular tissues and the nervous system. All the last groups are rich in neuropeptides. The endopeptidase exhibits high specificity constants for a number of these potential substrates, including tachykinins, enkephalins and bradykinin. In the brain, immunocytochemical studies have shown colocalization of the enzyme and substance P. Thus, endopeptidase-24.11 has the appropriate topology, specificity, kinetic properties and localization to play a role in the metabolism of regulatory peptides.