Characterization of a secreted form of human furin endoprotease.
Human furin, a member of a recently discovered family of cellular endoproteases, has been identified as a membrane bound protein localized in the Golgi apparatus. Here, we report the presence of a secreted form of furin in the media of cells infected with a vaccinia virus recombinant containing the furin gene. Using the fluorogenic substrate boc-Arg-Val-Arg-Arg-MCA, endoproteolytic activity was detected in the media of infected BSC40 cells. Immunoprecipitations of [35S]-labeled proteins from infected cells revealed that the media contained a lower molecular form of furin than the cellular furin or than a previously characterized soluble furin mutant, hFUR713t. By using the direct linear plot representation of the Michaelis-Menten equation the results demonstrate that the soluble furin exhibited similar kinetics to the hFUR713t enzyme. Thus, our results suggest that membrane-bound furin undergoes post-translational processing to produce a soluble form of the enzyme that can be secreted.
Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Québec, Canada.
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Vidricaire
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JB
Denault
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Leduc
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D045683:Furin; D006801:Humans; D007668:Kidney; D007700:Kinetics; D008969:Molecular Sequence Data; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013379:Substrate Specificity; D013381:Subtilisins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014616:Vaccinia virus / Q000235:genetics
D011506:Proteins; D011994:Recombinant Proteins; D013381:Subtilisins; D045683:Furin