Cdk, Cdc2 and Cdc28 & Clb1, Clb2, Clb3, or Clb4, phase

Although these complexes have a variety functions, CDKCs are most known for their role in the cell cycle. Initially, studies were conducted in Schizosaccharomyces pombe and Saccharomyces cerevisiae (yeast). S. pombe and S. cerevisiae are most known for their association with a single Cdk, Cdc2 and Cdc28 respectively, which complexes with several different cyclins. Depending on the cyclin, various portions of the cell cycle are affected. For example, in S. pombe, Cdc2 associates with Cdk13 to form the Cdk13-Cdc2 complex. In S. cerevisiae, the association of Cdc28 with cyclins, Cln1, Cln2, or Cln3, results in the transition from G1 phase to S phase. Once in the S phase, Cln1 and Cln2 dissociates with Cdc28 and complexes between Cdc28 and Clb5 or Clb6 are formed. In G2 phase, complexes formed from the association between Cdc28 and Clb1, Clb2, Clb3, or Clb4, results in the progression from G2 phase to M (Mitotic) phase. These complexes are present in early M phase as well. See Table 1 for a summary of yeast CDKCs.

From what is known about the complexes formed during each phase of the cell cycle in yeast, proposed models have emerged based on important phosphorylation sites and transcription factors involved.