TI  - <prot>cdc2</prot> phosphorylation is required for its interaction with cyclin.
PG  - 3311-9
AB  - Activation of the <prot>cdc2</prot> protein kinase at different stages of the cell
      cycle is regulated by post-translational modifications and interactions
      with cyclins. We show that in vitro translated human  <prot>cdc2</prot>   binds very
      poorly to  A and B cyclins  , unless it has been preincubated with a Xenopus
      egg extract. This results in the phosphorylation of <prot>cdc2</prot> which allows
      binding to cyclins. The replacement of Thr161, a residue conserved and
      phosphorylated in other protein kinases, with valine inhibits  <prot>cdc2</prot> 
      association with  A and B cyclins . In addition, mutations in the
      amino-terminus of <prot>cdc2</prot> and within the conserved 'PSTAIR' region strongly
      inhibit binding. The Thr161Val mutation causes a lethal phenotype in the
      fission yeast Schizosaccharomyces pombe, while replacement of Thr161 with
      glutamic acid, potentially mimicking phosphorylation, causes
      uncoordination of mitosis and multiple cytokinesis. These results suggest
      that a threonine phosphorylation/dephosphorylation cycle is involved in
      regulating <prot>cdc2</prot> function.
AD  - Differentiation Program, European Molecular Biology Laboratory,
