TABLE 2.
Functions of S. cerevisiae CDKs and their cyclin activators
| CDK | Cyclin | Functions and important properties | References |
|---|---|---|---|
| Cdc28 | Cln1 | Mediates glucose control of cell size at budding. All functions listed for Cln2. | 33, 112, 128, 129, 131, 184, 214, 411, 462, 533, 565, 578, 617 |
| Cln2 | Expressed at Start. Commits cell to mitotic division cycle (Start). Stimulates Sic1 degradation. Initiates localized growth leading to budding. Initiates SPB duplication. Represses pheromone-induced transcription. | 106, 112, 122, 128, 129, 131, 214, 328, 332, 411, 462, 533, 578, 617 | |
| Cln3 | Expressed throughout the cell cycle. Stimulates Start-specific transcription. Mediates cell size control. | 82, 107, 109, 129, 253, 327, 328, 396, 462, 534, 537, 578, 579, 621 | |
| Clb1 | Expressed at G2/M. Minor contributor to mitotic promoting factor. Most important cyclin for meiosis II. | 10, 160, 181, 196, 209, 460, 541 | |
| Clb2 | Expressed at G2/M. Major contributor to mitotic promoting factor. Promotes spindle elongation. Negatively regulates bud emergence. Promotes switch to depolarized bud growth. Represses SBF-mediated transcription. | 8, 10, 47, 160, 181, 209, 259, 332, 460, 540, 541 | |
| Clb3, Clb4 | Expressed in mid S to G2. Important for spindle formation. Can initiate S phase when Clb5 or Clb6 is lacking. | 160, 181, 209, 460, 487, 541 | |
| Clb5 | Expressed at Start. Important for S-phase initiation. Can stimulate SBF-regulated gene transcription. Prevents reinitiation on DNA replication origins that have already ’fired’. Has a possible role in spindle formation. Can fulfill essential Cln roles when overexpressed. | 34, 114, 160, 173, 310, 412, 486, 487, 519 | |
| Clb6 | Expressed at Start. Important for S-phase initiation. Represses Start-specific transcription. Has a possible role in spindle formation. Can fulfill essential Cln roles when overexpressed. | 34, 310, 486, 487 | |
| Pho85 | Clg1, Pcl1, Pcl2, Pcl5, Pcl9 | Roles in Start, bud emergence, and hyperpolarized growth (Δpcl1 Δpcl2 Δcln1 Δcln2 is lethal and fails to bud; Δclg1 Δpcl1 Δpcl2 Δpcl5 Δpcl9 has elongated buds and connected chains of cells). | 14, 166, 377, 378, 556 |
| Pho80 | Repressor of acid phosphatase transcription. | 243, 274, 326, 418, 481, 584 | |
| Pcl6, Pcl7 | Unknown function. | 14, 378 | |
| Pcl8, Pcl10 | Negative regulators of glycogen synthase 2. | 252, 378 | |
| Kin28 | Ccl1 | Phosphorylates carboxy terminal repeats on largest subunit of RNA polymerase II. Component of transcription factor TFIIH. | 93, 171, 172, 518, 545, 586, 587 |
| Ssn3a | Ssn8b | Phosphorylates carboxy terminal repeats on largest subunit of RNA polymerase II. Component of RNA polymerase II holoenzyme. | 309, 339, 542 |
| Ctk1 | Ctk2 | Phosphorylates carboxy terminal repeats on largest subunit of RNA polymerase II. | 324, 530 |
a
Ssn3 also known as Ume5, Srb10, and Are1.
b
Ssn8 also known as Sbr11 and Ume3.