MATURATION OF THE TRANS-GOLGI NETWORK PROTEASE FURIN - COMPARTMENTALIZATION OF PROPEPTIDE REMOVAL, SUBSTRATE CLEAVAGE, AND COOH-TERMINAL TRUNCATION

Citation
M. Vey et al., MATURATION OF THE TRANS-GOLGI NETWORK PROTEASE FURIN - COMPARTMENTALIZATION OF PROPEPTIDE REMOVAL, SUBSTRATE CLEAVAGE, AND COOH-TERMINAL TRUNCATION, The Journal of cell biology, 127(6), 1994, pp. 1829-1842
Citations number
72
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell Biology
Journal title
ISSN journal
0021-9525
Volume
127
Issue
6
Year of publication
1994
Part
2
Pages
1829 - 1842
Database
ISI
SICI code
0021-9525(1994)127:6<1829:MOTTNP>2.0.ZU;2-U
Abstract
We have cloned a bovine cDNA encoding the trans-Golgi network (TGN) pr otease furin and expressed it via recombinant vaccinia viruses to inve stigate intracellular maturation. Pulse-chase labeling reveals that th e 104-kD pro-furin bearing high mannose N-glycans is rapidly processed into the 98-kD protease whose N-glycans remain sensitive to endoglyco sidase H for a certain period of time. Furthermore, in the presence of brefeldin A, pro-furin cleavage occurs. From these data we conclude t hat the ER is the compartment of propeptide removal. Studies employing the ionophore A23187 and DTT show that autocatalysis is Ca2+ dependen t and that it does not occur under reducing conditions. Pro-furin prod uced under these conditions never gains endo H resistance indicating t hat it is retained in the ER. Coexpression of furin with the fowl plag ue virus hemagglutinin in the presence of brefeldin A and monensin rev eals that furin has to enter the Golgi region to gain substrate cleavi ng activity. N-glycans of furin are sialylated proving its transit thr ough the trans-Golgi network. A truncated form of furin is found in su pernatants of cells. Truncation is inhibited in the absence of Ca2+ io ns and in the presence of acidotropic agents indicating that it takes place in an acidic compartment of cells. Comparative analysis with fur in expressed from cDNA reveals that the truncated form prevails in pre parations of biologically active, endogenous furin obtained from MDBK cells. This observation supports the concept that secretion of truncat ed furin is a physiological event that may have important implications for the processing of extracellular substrates.