Concanavalin A alters the turnover rate of tyrosine aminotransferase in cultured hepatoma cells

Terrence M. Donohue, Kai Lin Lee, Francis T. Kenney

Research output: Contribution to journalArticle

Abstract

Concanavalin A added to monolayer cultures of Reuber H-35 hepatoma cells caused a rapid inactivation of tyrosine aminotransferase (l-tyrosine:2-oxoglutarate aminotransferase, E.C. 2.6.1.5) and loss of reactivity with antibody against the native, dimeric enzyme. Analysis of treated cells with an antibody raised against carboxymethylated, denatured enzyme showed that the inactivated enzyme was reactive with this reagent, which does not react with the native enzyme. Subsequent addition of α-methyl-d-mannopyranoside to remove concanavalin A restored both enzyme activity and reactivity to antibody against native enzyme. After long-term treatment with concanavalin A, the restored enzyme levels were significantly higher than in controls treated with the sugar but not the lectin. Analysis of the turnover of the enzyme by two methods revealed that the rate of its degradation is reduced about 2-fold in concanavalin A-treated cells. Treatment with H-35 cells with concanavalin A thus effects an alteration in conformation of tyrosine aminotransferase, rendering it somewhat less sensitive to intracellular degradation.

Original languageEnglish (US)
Pages (from-to)94-100
Number of pages7
JournalBBA - Molecular Cell Research
Volume721
Issue number1
DOIs
StatePublished - Sep 13 1982

Keywords

  • (Hepatoma cell)
  • Concanavalin A
  • Protein turnover
  • Tyrosine aminotransferase

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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