Vidricaire G, Denault J B, Leduc R
Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Québec, Canada.
Biochem Biophys Res Commun. 1993 Sep 15;195(2):1011-8. doi: 10.1006/bbrc.1993.2145.
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.
人弗林蛋白酶是最近发现的细胞内蛋白酶家族的成员，已被鉴定为一种定位于高尔基体的膜结合蛋白。在此，我们报告在感染了含弗林蛋白酶基因的痘苗病毒重组体的细胞培养基中存在一种分泌形式的弗林蛋白酶。使用荧光底物boc-Arg-Val-Arg-Arg-MCA，在感染的BSC40细胞培养基中检测到了内蛋白水解活性。对感染细胞中[35S]标记蛋白的免疫沉淀显示，培养基中弗林蛋白酶的分子形式比细胞内的弗林蛋白酶或先前鉴定的可溶性弗林蛋白酶突变体hFUR713t的分子形式小。通过使用米氏方程的直接线性图表示法，结果表明可溶性弗林蛋白酶表现出与hFUR713t酶相似的动力学。因此，我们的结果表明，膜结合的弗林蛋白酶经过翻译后加工产生一种可分泌的可溶性酶形式。
