Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase

Nature. 2001 Mar 8;410(6825):215-20. doi: 10.1038/35065617.


In vertebrate cells, the nuclear entry of Cdc2-cyclin B1 (MPF) during prophase is thought to be essential for the induction and coordination of M-phase events. Phosphorylation of cyclin B1 is central to its nuclear translocation, but the kinases that are responsible remain unknown. Here we have purified a protein kinase from Xenopus M-phase extracts that phosphorylates a crucial serine residue (S147) in the middle of the nuclear export signal sequence of cyclin B1. We have identified this kinase as Plx1 (ref. 16), a Xenopus homologue of Polo-like kinase (Plk)-1. During cell-cycle progression in HeLa cells, a change in the kinase activity of endogenous Plk1 toward S147 and/or S133 correlates with a kinase activity in the cell extracts. An anti-Plk1 antibody depletes the M-phase extracts of the kinase activity toward S147 and/or S133. An anti-phospho-S147 antibody reacts specifically with cyclin B1 only during G2/M phase. A mutant cyclin B1 in which S133 and S147 are replaced by alanines remains in the cytoplasm, whereas wild-type cyclin B1 accumulates in the nucleus during prophase. Co-expression of constitutively active Plk1 stimulates nuclear entry of cyclin B1. Our results indicate that Plk1 may be involved in targeting MPF to the nucleus during prophase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Butyrolactone / analogs & derivatives*
  • 4-Butyrolactone / pharmacology
  • Animals
  • Butadienes / pharmacology
  • CDC2 Protein Kinase / antagonists & inhibitors
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins
  • Cell Nucleus / metabolism*
  • Cyclin B / genetics
  • Cyclin B / immunology
  • Cyclin B / metabolism*
  • Cyclin B1
  • Enzyme Inhibitors / pharmacology
  • HeLa Cells
  • Humans
  • MAP Kinase Kinase Kinase 1*
  • Mitosis
  • Mutation
  • Nitriles / pharmacology
  • Phosphorylation
  • Precipitin Tests
  • Prophase*
  • Protein Kinases / metabolism*
  • Protein Transport
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / isolation & purification
  • Protein-Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins
  • Xenopus
  • Xenopus Proteins*


  • Butadienes
  • CCNB1 protein, human
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclin B1
  • Enzyme Inhibitors
  • Nitriles
  • Proto-Oncogene Proteins
  • U 0126
  • Xenopus Proteins
  • butyrolactone I
  • Protein Kinases
  • Plk1 protein, Xenopus
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • CDC2 Protein Kinase
  • MAP Kinase Kinase Kinase 1
  • MAP3K1 protein, human
  • 4-Butyrolactone