Glycolipid precursors for the membrane anchor of Trypanosoma brucei variant surface glycoproteins. II. Lipid structures of phosphatidylinositol-specific phospholipase C sensitive and resistant glycolipids. Academic Article uri icon

Overview

MeSH

  • Animals
  • Chromatography, Thin Layer
  • Ethanolamine
  • Ethanolamines
  • Glucosamine
  • Glycosylphosphatidylinositols
  • Myristic Acid
  • Myristic Acids
  • Palmitic Acid
  • Palmitic Acids
  • Phospholipases
  • Radioisotope Dilution Technique
  • Tritium

MeSH Major

  • Glycolipids
  • Phosphatidylinositols
  • Trypanosoma brucei brucei
  • Type C Phospholipases
  • Variant Surface Glycoproteins, Trypanosoma

abstract

  • A common diagnostic feature of glycosylinositol phospholipid (GPI)-anchored proteins is their release from the membrane by a phosphatidylinositol-specific phospholipase C (PI-PLC). However, some GPI-anchored proteins are resistant to this enzyme. The best characterized example of this subclass is the human erythrocyte acetylcholinesterase, where the structural basis of PI-PLC resistance has been shown to be the acylation of an inositol hydroxyl group(s) (Roberts, W. L., Myher, J. J., Kuksis, A., Low, M. G., and Rosenberry, T. L. (1988) J. Biol. Chem. 263, 18766-18775). Both PI-PLC-sensitive and resistant GPI-anchor precursors (P2 and P3, respectively) have been found in Trypanosoma brucei, where the major surface glycoprotein is anchored by a PI-PLC-sensitive glycolipid anchor. The accompanying paper (Mayor, S., Menon, A. K., Cross, G. A. M., Ferguson, M. A. J., Dwek, R. A., and Rademacher, T. W. (1990) J. Biol. Chem. 265, 6164-6173) shows that P2 and P3 have identical glycans, indistinguishable from the common core glycan found on all the characterized GPI protein anchors. This paper shows that the single difference between P2 and P3, and the basis for the PI-PLC insusceptibility of P3, is a fatty acid, ester-linked to the inositol residue in P3. The inositol-linked fatty acid can be removed by treatment with mild base to restore PI-PLC sensitivity. Biosynthetic labeling experiments with [3H]palmitic acid and [3H]myristic acid show that [3H]palmitic acid specifically labels the inositol residue in P3 while [3H]myristic acid labels the diacylglycerol portion. Possible models to account for the simultaneous presence of PI-PLC-resistant and sensitive glycolipids are discussed in the context of available information on the biosynthesis of GPI-anchors.

publication date

  • April 15, 1990

has subject area

  • Animals
  • Chromatography, Thin Layer
  • Ethanolamine
  • Ethanolamines
  • Glucosamine
  • Glycolipids
  • Glycosylphosphatidylinositols
  • Myristic Acid
  • Myristic Acids
  • Palmitic Acid
  • Palmitic Acids
  • Phosphatidylinositols
  • Phospholipases
  • Radioisotope Dilution Technique
  • Tritium
  • Trypanosoma brucei brucei
  • Type C Phospholipases
  • Variant Surface Glycoproteins, Trypanosoma

Research

keywords

  • Journal Article

Identity

Language

  • eng

PubMed ID

  • 2138615

Additional Document Info

start page

  • 6174

end page

  • 6181

volume

  • 265

number

  • 11