The Cdk-activating kinase (CAK) from budding yeast

Cell. 1996 Aug 23;86(4):553-64. doi: 10.1016/s0092-8674(00)80129-4.


Activation of the cyclin-dependent kinases to promote cell cycle progression requires their association with cyclins as well as phosphorylation of a threonine (residue 161 in human p34cdc2). This phosphorylation is carried out by CAK, the Cdk-activating kinase. We have purified and cloned CAK from S. cerevisiae. Unlike CAKs from other organisms, Cak1p is active as a monomer, has full activity when expressed in E. coli, and is not a component of the basal transcription factor, TFIIH. A temperature-sensitive mutation in CAK1 confers a G2 delay accompanied by low Cdc28p protein kinase activity and shows genetic interactions with altered expression of the gene for the major mitotic cyclin, CLB2. Our data raise the intriguing possibility that p40MO15-cyclin H-MAT1, identified as the predominant CAK in vertebrate cell extracts, may not function as a physiological CAK.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • CDC2-CDC28 Kinases*
  • CDC28 Protein Kinase, S cerevisiae / metabolism
  • Cell Cycle Proteins / genetics*
  • Cell Cycle*
  • Cyclin B*
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases / metabolism
  • Cyclins / metabolism
  • Fungal Proteins / genetics
  • Genes, Fungal*
  • Molecular Sequence Data
  • Molecular Weight
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Structure-Activity Relationship


  • CLB2 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclins
  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Protein-Serine-Threonine Kinases
  • CDC2-CDC28 Kinases
  • CDC28 Protein Kinase, S cerevisiae
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases
  • cyclin-dependent kinase-activating kinase

Associated data

  • GENBANK/U60192