CDK activation by non-cyclin proteins

Curr Opin Cell Biol. 2006 Apr;18(2):192-8. doi: 10.1016/ Epub 2006 Feb 17.


Progression through the cell cycle is regulated by cyclin-dependent kinases (CDKs), which associate with activating partners, named cyclins, to phosphorylate substrates efficiently. Cyclins are periodically synthesized and degraded during the cell cycle, playing a key role in the precise activation and inactivation of CDKs. However, CDKs can also be activated by other proteins, which lack sequence similarity to cyclins. These include the RINGO/Speedy proteins, which were originally identified as regulators of the meiotic cell cycle in Xenopus oocytes. Recently, five different mammalian RINGO/Speedy family members have been reported, all of which can bind to and directly activate Cdk1 and Cdk2.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • CDC2 Protein Kinase / genetics
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle / genetics
  • Cell Cycle / physiology*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cyclin-Dependent Kinase 2 / genetics
  • Cyclin-Dependent Kinase 2 / metabolism
  • Cyclin-Dependent Kinases / genetics
  • Cyclin-Dependent Kinases / metabolism*
  • Enzyme Activation
  • Humans
  • Models, Biological
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Phylogeny
  • Xenopus Proteins / genetics
  • Xenopus Proteins / metabolism


  • Cell Cycle Proteins
  • Nerve Tissue Proteins
  • SPDYA protein, human
  • Xenopus Proteins
  • ls27 protein, Xenopus
  • neuronal Cdk5 activator (p25-p35)
  • CDC2 Protein Kinase
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases