Characterization of the molecular forms of glutathione S-transferase P1 in human gastric cancer cells (Kato III) and in normal human erythrocytes

Perungavar N. Ranganathan, Richard Whalen, Thomas D. Boyer

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

GSTP1 (glutathione S-transferase pi) is involved in stress responses and in cellular proliferation pathways as an inhibitor of JNK (c-Jun N-terminal kinase). It has been proposed that monomeric GSTP1 functions as a JNK inhibitor. All of the studies to date have been performed using rodent cells, and it is unclear if monomeric GSTP1 exists in human cells. Monomeric GSTP1 was sought in human gastric cancer cells (Kato III) and in normal human erythrocytes using gel filtration, ELISA and Western blots. Monomeric GSTP1 was found in conditioned medium, in cytosol of Kato III cells and in cytosol of erythrocytes. GSTP1 subunits from Kato III cells and erythrocytes were heterogeneous when analysed by MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS, suggesting that there were post-translational modifications to GSTP1. One post-translational modification, phosphorylation of a serine residue in the C-terminal portion of GSTP1 where JNK binds, was identified in GSTP1 purified from Kato III cells, but not in GSTP1 purified from human erythrocytes. Therefore normal and malignant human cells contain GSTP1 monomers with post-translational modifications, and it is likely that GSTP1 monomers regulate JNK activity in human cells in the same manner as in rodent cells.

Original languageEnglish (US)
Pages (from-to)525-533
Number of pages9
JournalBiochemical Journal
Volume386
Issue number3
DOIs
StatePublished - Mar 15 2005

Keywords

  • Glutathione S-transferase (GST)
  • MS
  • Monomer
  • Post-translational modification
  • c-Jun N-terminal kinase (JNK)

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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