Open AccessReciprocal relationship between α1,2 mannosidase processing and reglucosylation in the rough endoplasmic reticulum of Man‐ P ‐Dol deficient cells
Author(s) -
Duvet Sandrine,
Chirat Frédéric,
Mir AnneMarie,
Verbert André,
Dubuisson Jean,
Cacan René
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01111.x
Subject(s) - mannosidase , endoplasmic reticulum , glycosylation , glycoprotein , chemistry , golgi apparatus , swainsonine , microbiology and biotechnology , endoplasmic reticulum associated protein degradation , intracellular , enzyme , mutant , n acetylglucosamine , biochemistry , biology , unfolded protein response , gene
The study of the glycosylation pathway of a mannosylphosphoryldolichol‐deficient CHO mutant cell line (B3F7) reveals that truncated Glc (0–3) Man 5 GlcNAc 2 oligosaccharides are transferred onto nascent proteins. Pulse‐chase experiments indicate that these newly synthesized glycoproteins are retained in intracellular compartments and converted to Man 4 GlcNAc 2 species. In this paper, we demonstrate that the α1,2 mannosidase, which is involved in the processing of Man 5 GlcNAc 2 into Man 4 GlcNAc 2 , is located in the rough endoplasmic reticulum. The enzyme was shown to be inhibited by kifunensine and deoxymannojirimycin, indicating that it is a class I mannosidase. In addition, Man 4 GlcNAc 2 species were produced at the expense of Glc 1 Man 5 GlcNAc 2 species. Thus, the trimming of Man 5 GlcNAc 2 to Man 4 GlcNAc 2 , which is catalyzed by this mannosidase, could be involved in the control of the glucose‐dependent folding pathway.