Different kinases phosphorylate nucleophosmin/B23 at different sites during G(2) and M phases of the cell cycle

Cancer Lett. 2000 May 29;153(1-2):151-60. doi: 10.1016/s0304-3835(00)00362-1.


The recombinant GST-nucleophosmin/B23 and the truncated mutants were tested for phosphorylation in cell-free extracts of G(2) and M phases or by purified kinases. Our results indicated that a threonine residue at amino acids (a.a.) 185-240 was phosphorylated by cdc2 kinase during the entry of mitosis while the serine phosphorylation site at the middle acidic portion of the molecule (a. a. 83-152) was phosphorylated by casein kinase II during G(2) phase. Our results also showed that there was possibly another serine phosphorylation at site other than the middle portion of nucleophosmin/B23 (a.a. 83-152) during the entry of cells into mitosis. The demonstration of the characteristic changes in phosphorylation of nucleophosmin/B23 during the cell cycle implicates important role of nucleophosmin/B23 in the control of the fate of nucleoli and cell growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • G2 Phase / physiology*
  • HeLa Cells
  • Humans
  • Mitosis / physiology*
  • Molecular Sequence Data
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Phosphotransferases / metabolism*


  • Nuclear Proteins
  • nucleophosmin
  • Phosphotransferases