Nucleolar localization of nucleophosmin/B23 requires GTP

J Biol Chem. 1993 Mar 15;268(8):5823-7.


Incubation of HeLa cells with the IMP dehydrogenase inhibitors: ribavirin (100 microM, 4 h), tiazofurin (100 microM, 4 h), selenazofurin (100 microM, 4 h), or mycophenolic acid (10 microM, 4 h) resulted in approximately 70% reduction in cellular GTP pools and shifting of nucleophosmin/B23 from nucleoli to nucleoplasm as detected by immunofluorescence (B23-translocation). Enzyme-linked immunosorbent assay and Western blot assay showed there is no loss or degradation of nucleophosmin/B23 protein during drug treatment. This translocation effect could be prevented by co-incubation with guanosine (100 microM) or reversed by addition of guanosine (100 microM) to the culture medium after B23-translocation had been induced by these inhibitors. Under these conditions of guanosine supplementation, cellular GTP pool concentrations were maintained at the control level. These results indicate that localization of nucleophosmin/B23 into the nucleolus is dependent on the cellular GTP level.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Transport
  • Cell Nucleolus / metabolism*
  • Guanosine Triphosphate / metabolism*
  • HeLa Cells
  • Humans
  • IMP Dehydrogenase / antagonists & inhibitors
  • Nuclear Proteins / metabolism*
  • Nucleophosmin
  • Phosphoproteins / metabolism*
  • Ribavirin / analogs & derivatives
  • Ribavirin / pharmacology


  • NPM1 protein, human
  • Nuclear Proteins
  • Phosphoproteins
  • Nucleophosmin
  • Ribavirin
  • Guanosine Triphosphate
  • IMP Dehydrogenase