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

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