The glycophospholipid anchor of Thy-1. Biosynthetic labeling experiments with wild-type and class E Thy-1 negative lymphomas

S. H. Fatemi, R. Haas, N. Jentoft, T. L. Rosenberry, A. M. Tartakoff

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24 Scopus citations

Abstract

The Thy-1 antigen of the surface of lymphocytes and neurons is anchored to the plasma membrane via a glycophospholipid moiety. In contrast, the Thy-1 synthesized by the class E Thy-1 negative mutant lymphoma is secreted as a hydrophilic species. The present investigation uses the approach of biosynthetic labeling to investigate further the structure of the intracellular Thy-1 of wild-type cells and the secreted Thy-1 of these mutant cells. In the wild-type cells, Thy-1 can be labeled with [3H]mannose, [3H]galactose, [3H]fucose, [3H]ethanolamine, and [3H]palmitic acid. In the latter two cases the label is recovered almost exclusively in a detergent-binding Pronase fragment of the protein. The incorporated label is in the form of [3H]ethanolamine, or [3H]palmitate and stearate, respectively. Reductive methylation of biosynthetically labeled Thy-1 and a nonradioactive sample of Thy-1 shows that [3H]ethanolamine is incorporated equally into two residues of ethanolamine, only one of which has a free amino group. A single residue of glucosamine with a free amino group is also detected. Each of the sugar precursors is incorporated with extensive conservation of chemical identity. In the class E cells, each of the labeled sugars but neither [3H]ethanolamine nor [3H]palmitate is incorporated into Thy-1. The anchor moiety therefore appears to be entirely missing, although N-linked oligosaccharide processing is essentially normal. We postulate that the anchor deficiency in the mutant cells results from a biosynthetic lesion.

Original languageEnglish (US)
Pages (from-to)4728-4732
Number of pages5
JournalJournal of Biological Chemistry
Volume262
Issue number10
StatePublished - Sep 17 1987

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Fatemi, S. H., Haas, R., Jentoft, N., Rosenberry, T. L., & Tartakoff, A. M. (1987). The glycophospholipid anchor of Thy-1. Biosynthetic labeling experiments with wild-type and class E Thy-1 negative lymphomas. Journal of Biological Chemistry, 262(10), 4728-4732.