Initiation of the decorin glycosaminoglycan chain in the endoplasmic reticulum-Golgi intermediate compartment

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Abstract

We have transiently expressed decorin with a C- terminal KDEL endoplasmic reticulum retention signal peptide in COS- 7 cells to study initiation of galactosaminoglycan synthesis in the endoplasmic reticulum- Golgi intermediate compartment. All decorin- KDEL molecules were substituted with N- linked oligosaccharides sensitive to endoglycosidase H, indicating that the core protein was located proximal to the medial- Golgi. O-Linked glycosylation was only initiated in a minor fraction of the molecules. The O- linked saccharides were characterized by gel filtration after stepwise degradations using chondroitin ABC/ AC-I lyases, beta1 - 3- glycuronidase, beta-galactosidase, and alkaline phosphatase. The major O- linked saccharide was the linkage region pentasaccharide GalNAcbeta1-4GlcUAbeta1-3Galbeta1-3Galbeta1-4-Xyl- 2- phosphate, demonstrating initiation of chondroitin synthesis in the endoplasmic reticulum- Golgi intermediate compartment. In the presence of brefeldin A, partial elongation of a chondroitin chain took place, indicating retrieval of polymerases but not of sulfotransferases.

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  • Cell and Molecular Biology
Original languageEnglish
Pages (from-to)21415-21420
JournalJournal of Biological Chemistry
Volume278
Issue number24
StatePublished - 2003
Publication categoryResearch
Peer-reviewedYes