Sphingomyelin modulates the transbilayer distribution of galactosylceramide in phospholipid membranes

Peter Mattjus, B Malewicz, JT Valiyaveettil, WJ Baumann, R Bittman, RE Brown

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    Abstract

    The interrelationships among sphingolipid structure, membrane curvature, and glycosphingolipid transmembrane distribution remain poorly defined despite the emerging importance of sphingolipids in curved regions and vesicle buds of biomembranes. Here, we describe a novel approach to investigate the transmembrane distribution of galactosylceramide in phospholipid small unilamellar vesicles by C-13 NMR spectroscopy. Quantitation of the transbilayer distribution of [6-C-13]galactosylceramide (99.8% isotopic enrichment) was achieved by exposure of vesicles to the paramagnetic ion, Mn2+. The data show that [6-13C]galactosylceramide prefers (70%) the inner leaflet of phosphatidylcholine vesicles. Increasing the sphingomyelin content of the 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles shifted galactosylceramide from the inner to the outer leaflet. The amount of galactosylceramide localized in the inner leaflet decreased from 70% in pure 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles to only 40% in 1-palmitoyl-2-oleoyl-phosphatidylcholine/sphingomyelin (1:2) vesicles. The present study demonstrates that sphingomyelin can dramatically alter the transbilayer distribution of a monohexosylceramide, such as galactosylceramide, in 1-palmitoyl-2-oleoyl-phosphatidylcholine/sphingomyelin vesicles. The results suggest that sphingolipid-sphingolipid interactions that occur even in the absence of cholesterol play a role in controlling the transmembrane distributions of cerebrosides.
    Original languageUndefined/Unknown
    Pages (from-to)19476–19481
    Number of pages6
    JournalJournal of Biological Chemistry
    Volume277
    Issue number22
    DOIs
    Publication statusPublished - 2002
    MoE publication typeA1 Journal article-refereed

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