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An NADH-diaphorase is located at the cell plasma membrane in a mouse neuroblastoma cell line NB41A3.
Journal article

An NADH-diaphorase is located at the cell plasma membrane in a mouse neuroblastoma cell line NB41A3.

  • 1994-01-04
Published in:
  • Biochimica et biophysica acta. - 1994
Animals
Cell Division
Cell Membrane
Dihydrolipoamide Dehydrogenase
Mice
Neuroblastoma
Oxidation-Reduction
Permeability
Tumor Cells, Cultured
English Plasma membranes from most mammalian cells display significant transplasma membrane oxidoreductase (PMO) activity. The enzymes use an extracellular, impermeant electron acceptor as substrate and intracellular reduced pyridine nucleotide as electron donor. The plasma membrane from a neuroblastoma cell line, NB41A3, has been biotinylated and purified by immunoprecipitation with avidin and antiavidin-antibodies. The protein recovery of an immunopurified membrane preparation was < 0.15% of the protein content in the cell extract. The preparation displays an increase in the specific activity of PMO's of 15- to 20-fold compared to the activity in whole cells. With this approach the presence of a NADH-diaphorase within the cell plasma membrane can be demonstrated. This activity accounts for about one third of the total cellular diaphorase activity. The PMO activity cannot be attributed to an increased permeabilization of the plasma membrane induced upon biotinylation nor to intracellular activity from lysed cells. Activation of basal metabolism (glycolysis) stimulates PMO activity up to approx. 54%, presumably through a raise of the intracellular NADH store. PMO also promotes cell growth at low substrate concentrations (0.1-1 microM). Native gel electrophoresis of iminobiotinylated and affinity purified plasma membrane extracts displays two diaphorase-positive bands, indicating that a homogeneous cell population may express several PMO activities at the plasma membrane.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://sonar.ch/global/documents/93823
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