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Regulation of MBK-2/DYRK by CDK-1 and the pseudophosphatases EGG-4 and EGG-5 during the oocyte-to-embryo transition.

DYRKs are kinases that self-activate in vitro by autophosphorylation of a YTY motif in the kinase domain, but their regulation in vivo is not well understood. In C. elegans zygotes, MBK-2/DYRK phosphorylates oocyte proteins at the end of the meiotic divisions to promote the oocyte-to-embryo transition. Here we demonstrate that MBK-2 is under both positive and negative regulation during the transition. MBK-2 is activated during oocyte maturation by CDK-1-dependent phosphorylation of serine 68, a residue outside of the kinase domain required for full activity in vivo. The pseudotyrosine phosphatases EGG-4 and EGG-5 sequester activated MBK-2 until the meiotic divisions by binding to the YTY motif and inhibiting MBK-2's kinase activity directly, using a mixed-inhibition mechanism that does not involve tyrosine dephosphorylation. Our findings link cell-cycle progression to MBK-2/DYRK activation and the oocyte-to-embryo transition.

Pubmed ID: 19879842


  • Cheng KC
  • Klancer R
  • Singson A
  • Seydoux G



Publication Data

October 30, 2009

Associated Grants

  • Agency: NICHD NIH HHS, Id: R01 HD037047
  • Agency: NICHD NIH HHS, Id: R01 HD037047-10
  • Agency: NICHD NIH HHS, Id: R01HD054681
  • Agency: NICHD NIH HHS, Id: R01HD37047
  • Agency: Howard Hughes Medical Institute, Id:

Mesh Terms

  • Animals
  • CDC2 Protein Kinase
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins
  • Embryo, Nonmammalian
  • Humans
  • Oocytes
  • Protein-Tyrosine Kinases