A novel glycosylphosphatidylinositol in African trypanosomes

a possible catabolic intermediate

Kenneth G. Milne, Michael A. J. Ferguson, Paul T. Englund

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    The major glycosylphosphatidylinositols (GPIs) in African trypanosomes are glycolipid A, the precursor of the variant surface glycoprotein membrane anchor, and glycolipid C, a species identical to glycolipid A except that it contains an acylated inositol. Both glycolipids A and C contain dimyristoyl glycerol and are efficiently labeled with [H-3]myristate in a cell free system. We now report a novel GPI known as lipid X. This GPI is radio-labeled strongly with [H-3]palmitate (and very poorly with [H-3]myristate or [H-3]stearate) in digitonin-permeabilized cells. The structure of lipid X is Man(1)GlcNAc-(2-O-palmitoyl)-D-myo-inositol-1-HPO4-3(lyso-palmitoylglycerol). Metabolically, lipid X exists as an intermediate, and can be detected only under conditions in which its formation is stimulated (e.g. by EDTA) or its breakdown is inhibited (e.g. by Co2+). Lipid X has not been observed previously because these conditions do not support GPI biosynthesis We speculate that lipid X is an intermediate in the catabolism of conventional trypanosome GPIs possibly deriving from breakdown of glycolipid C.

    Original languageEnglish
    Pages (from-to)1465-1471
    Number of pages7
    JournalJournal of Biological Chemistry
    Volume274
    Issue number3
    DOIs
    Publication statusPublished - 15 Jan 1999

    Cite this

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    abstract = "The major glycosylphosphatidylinositols (GPIs) in African trypanosomes are glycolipid A, the precursor of the variant surface glycoprotein membrane anchor, and glycolipid C, a species identical to glycolipid A except that it contains an acylated inositol. Both glycolipids A and C contain dimyristoyl glycerol and are efficiently labeled with [H-3]myristate in a cell free system. We now report a novel GPI known as lipid X. This GPI is radio-labeled strongly with [H-3]palmitate (and very poorly with [H-3]myristate or [H-3]stearate) in digitonin-permeabilized cells. The structure of lipid X is Man(1)GlcNAc-(2-O-palmitoyl)-D-myo-inositol-1-HPO4-3(lyso-palmitoylglycerol). Metabolically, lipid X exists as an intermediate, and can be detected only under conditions in which its formation is stimulated (e.g. by EDTA) or its breakdown is inhibited (e.g. by Co2+). Lipid X has not been observed previously because these conditions do not support GPI biosynthesis We speculate that lipid X is an intermediate in the catabolism of conventional trypanosome GPIs possibly deriving from breakdown of glycolipid C.",
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    year = "1999",
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    A novel glycosylphosphatidylinositol in African trypanosomes : a possible catabolic intermediate. / Milne, Kenneth G.; Ferguson, Michael A. J. ; Englund, Paul T. .

    In: Journal of Biological Chemistry, Vol. 274, No. 3, 15.01.1999, p. 1465-1471.

    Research output: Contribution to journalArticle

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    N2 - The major glycosylphosphatidylinositols (GPIs) in African trypanosomes are glycolipid A, the precursor of the variant surface glycoprotein membrane anchor, and glycolipid C, a species identical to glycolipid A except that it contains an acylated inositol. Both glycolipids A and C contain dimyristoyl glycerol and are efficiently labeled with [H-3]myristate in a cell free system. We now report a novel GPI known as lipid X. This GPI is radio-labeled strongly with [H-3]palmitate (and very poorly with [H-3]myristate or [H-3]stearate) in digitonin-permeabilized cells. The structure of lipid X is Man(1)GlcNAc-(2-O-palmitoyl)-D-myo-inositol-1-HPO4-3(lyso-palmitoylglycerol). Metabolically, lipid X exists as an intermediate, and can be detected only under conditions in which its formation is stimulated (e.g. by EDTA) or its breakdown is inhibited (e.g. by Co2+). Lipid X has not been observed previously because these conditions do not support GPI biosynthesis We speculate that lipid X is an intermediate in the catabolism of conventional trypanosome GPIs possibly deriving from breakdown of glycolipid C.

    AB - The major glycosylphosphatidylinositols (GPIs) in African trypanosomes are glycolipid A, the precursor of the variant surface glycoprotein membrane anchor, and glycolipid C, a species identical to glycolipid A except that it contains an acylated inositol. Both glycolipids A and C contain dimyristoyl glycerol and are efficiently labeled with [H-3]myristate in a cell free system. We now report a novel GPI known as lipid X. This GPI is radio-labeled strongly with [H-3]palmitate (and very poorly with [H-3]myristate or [H-3]stearate) in digitonin-permeabilized cells. The structure of lipid X is Man(1)GlcNAc-(2-O-palmitoyl)-D-myo-inositol-1-HPO4-3(lyso-palmitoylglycerol). Metabolically, lipid X exists as an intermediate, and can be detected only under conditions in which its formation is stimulated (e.g. by EDTA) or its breakdown is inhibited (e.g. by Co2+). Lipid X has not been observed previously because these conditions do not support GPI biosynthesis We speculate that lipid X is an intermediate in the catabolism of conventional trypanosome GPIs possibly deriving from breakdown of glycolipid C.

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