Identification of a glycolipid precursor of the Trypanosoma brucei variant surface glycoprotein

J. L. Krakow, D. Hereld, J. D. Bangs, G. W. Hart, P. T. Englund

Research output: Contribution to journalArticlepeer-review

Abstract

The variant surface glycoprotein (VSG) of Trypanosoma brucei has a glycolipid covalently attached to its C terminus. This glycolipid, which anchors the protein to the cell membrane, is attached to the VSG polypeptide within 1 min after translation (Bangs, J.D., Hereld, D., Krakow, J.L., Hart, G.W., and Englund, P.T. (1985) Proc. Natl. Sci. U.S.A. 82, 3207-3211). This rapid processing suggests that, prior to incorporation, the glycolipid may exist in the cell as a preformed precursor which is transferred to the VSG polypeptide en bloc. We have isolated a molecule which has properties consistent with it being a VSG glycolipid precursor. It is highly polar and can be labeled by [3H] myristate but not by [3H]palmitate. It reaches steady state during continuous labeling with [3H]myristate and shows rapid turnover in pulse-chase experiments, suggesting that it is a metabolic intermediate rather than an end product. When treated with HNO2 it liberates phosphatidylinositol, as does VSG (Ferguson, M.A.J., Low, M.G., and Cross, G.A.M. (1985) J. Biol. Chem. 260, 14547-14555). Also, like VSG, it releases a compound which co-migrates on thin layer chromatography with dimyristylglycerol when treated with the purified endogenous phospholipase C from trypanosomes. After treatment with this lipase, the putative precursor can be immunoprecipitated by antibodies directed against the C-terminal cross-reactive antigenic determinant of the VSG. These data provide strong evidence that this glycolipid is a VSG precursor.

Original languageEnglish (US)
Pages (from-to)12147-12153
Number of pages7
JournalJournal of Biological Chemistry
Volume261
Issue number26
StatePublished - 1986

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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