Identification of a novel family of non-lysosomal aspartic proteases in nematodes

Abstract

A protein encoded by cDNAs from the human parasite Onchocerca volvulus and its homologs from Caenorhabditis elegans and Ancyclostoma caninum define a family of aspartic proteases that are most closely related to cathepsins D, but differ from them in lacking the N-glycosylation site known to be required for lysosomal targeting. The nematode proteins have a potential N- glycosylation site at the same position as mammalian cathepsins E and in common with these have atypically long N-terminal extensions. The literature implies that cathepsins E may be secreted, and adult female O. secreted volvulus are known to secrete a specific inhibitor of aspartic proteases; we therefore predict that the protease is as an enzyme-inhibitor complex. Show more