Biosynthesis of heterogeneous forms of multidrug resistance-associated glycoproteins

L. M. Greenberger, S. S. Williams, S. B. Horwitz

Research output: Contribution to journalArticle

73 Scopus citations

Abstract

Multidrug-resistant J774.2 mouse macrophage-like cells, selected for resistance to colchicine, vinblastine, or taxol, overexpress antigenically related glycoproteins with distinct electrophoretic mobilities. These plasma membrane glycoproteins are likely to play a pivotal role in the expression of the multidrug resistance phenotype. To determine how these multidrug resistance-associated glycoproteins differ, the biosynthesis and N-linked carbohydrate composition of these proteins were examined and compared. Vinblastine- or colchicine-selected cells made a 125-kDa precursor that was rapidly processed (t( 1/2 ) ≃ 20 min) to mature forms of 135 and 140 kDa, respectively. Heterogeneity between the 135- and 140-kDa forms of the molecule can be attributed to N-linked carbohydrate. In contrast, taxol-selected cells made two precursors, 125 and 120 kDa, which appeared within 5 and 15 min after the onset of pulse labeling, respectively. They were processed to mature forms of 140 and 130 kDa. Since a single deglycosylated precursor or mature form was not observed after enzymatic removal of N-linked oligosaccharides, other differences, besides N-linked glycosylation, which occur in early processing compartments, are likely to account for the two multidrug resistance-associated glycoproteins in taxol-selected cells. These results demonstrate that a family of multidrug resistance-associated glycoproteins can be differentially expressed.

Original languageEnglish (US)
Pages (from-to)13685-13689
Number of pages5
JournalJournal of Biological Chemistry
Volume262
Issue number28
StatePublished - Jan 1 1987

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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