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Recycling of a glycosylphosphatidylinositol-anchored heparan sulphate proteoglycan (glypican) in skin fibroblasts

In English

Författare

Summary, in English

We have used suramin and brefeldin A to investigate the nature of a heparan sulphate proteoglycan that appears to recycle from the cell surface to intracellular compartments which synthesize new heparan sulphate chains. Suramin, which would block internalization and deglycanation of a putative recycling cell surface proteoglycan, markedly increases the yield of a membrane-bound proteoglycan with a core protein of 60-70 kDa and unusually long heparan sulphate side chains. When transport of newly made core proteins to their Golgi sites for glycosaminoglycan assembly is blocked, by using brefeldin A, [3H]glucosamine and [35S]sulphate incorporation into cell surface-bound heparan sulphate proteoglycan can still take place. After chemical biotinylation of cell surface proteins in brefeldin A-treated cells, followed by metabolic [35S]sulphation in the presence of the same drug, biotin-tagged [35S]proteoglycan can be demonstrated, indicating the presence of recycling proteoglycan species. By pre-labelling cells with [3H]leucine or [3H]inositol in the presence of suramin, followed by chase labelling with [35S]sulphate in the presence of brefeldin A, a 3H- and 35S-labelled, hydrophobic heparan sulphate proteoglycan with a core protein of 60-65 kDa is obtained. The proteoglycan loses its hydrophobicity when glucosamine-inositol bonds are cleaved, indicating that it is membrane bound via a glycosylphosphatidylinositol anchor. However, treatment with phosphatidylinositol-specific phospholipase C has no effect, suggesting that the inositol moiety may be acylated. We propose that a portion of the lipid-anchored proteoglycan glypican is internalized, recycled via the Golgi, where heparan sulphate chains are added, and finally re-deposited at the cell surface.

Publiceringsår

1995

Språk

Engelska

Sidor

407-415

Publikation/Tidskrift/Serie

Glycobiology

Volym

5

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Oxford University Press

Ämne

  • Biochemistry and Molecular Biology

Nyckelord

  • glycosylphosphatidylinositol-anchored/glypican/ heparan sulphate/proteoglycan/recycling

Status

Published

Forskningsgrupp

  • Glycobiology

ISBN/ISSN/Övrigt

  • ISSN: 1460-2423