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Differential effects of glycosphingolipids on the detergent-insolubility of the glycosylphosphatidylinositol-anchored membrane dipeptidase.

Parkin, Edward T. and Turner, Anthony J. and Hooper, Nigel M. (2001) Differential effects of glycosphingolipids on the detergent-insolubility of the glycosylphosphatidylinositol-anchored membrane dipeptidase. Biochemical Journal, 358 (1). pp. 209-216. ISSN 0264-6021

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Abstract

The insolubility of glycosylphosphatidylinositol (GPI)-anchored proteins in certain detergents appears to be an intrinsic property of their association with sphingolipids and cholesterol in lipid rafts. We show that the GPI-anchored protein membrane dipeptidase is localized in detergent-insoluble lipid rafts isolated from porcine kidney microvillar membranes, and that these rafts, which lack caveolin, are enriched not only in sphingomyelin and cholesterol, but also in the glycosphingolipid lactosylceramide (LacCer). Dipeptidase purified from porcine kidney was reconstituted into artificial liposomes in order to investigate the relationship between glycosphingolipids and GPI-anchored protein detergent-insolubility. Dipeptidase was insoluble in liposomes containing extremely low concentrations of LacCer. In contrast, identical concentrations of glucosylceramide or galactosylceramide failed to promote significant detergent-insolubility. Cholesterol was shown to enhance the detergent-insoluble effect of LacCer. GC–MS analysis revealed dramatic differences between the fatty acyl compositions of LacCer and those of the other glycosphingolipids. However, despite these differences, we show that the unusually marked effect of LacCer to promote the detergent-insolubility of dipeptidase cannot be singularly attributed to the fatty acyl composition of this glycosphingolipid molecule. Instead, we suggest that the ability of LacCer to confer detergent-insolubility on this GPI-anchored protein is dependent on the structure of the lipid molecule in its entirety, and that this glycosphingolipid may have an important role to play in the stabilization of lipid rafts, particularly the caveolin-free glycosphingolipid signalling domains.

Item Type: Article
Journal or Publication Title: Biochemical Journal
Uncontrolled Keywords: caveolin ; cholesterol ; lactosylceramide ; lipid rafts ; sphingomyelin.
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Health and Medicine > Biomedical & Life Sciences
ID Code: 9453
Deposited By: Dr Edward Parkin
Deposited On: 11 Jun 2008 10:55
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 18:37
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/9453

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