CDKs and Cyclins in The Cell Cycle
Most of the known cyclin-CDK complexes regulate the progression through the cell cycle. Animal cells contain at least nine CDKs, four of which, Cdk1, 2, 3, and 4, are directly involved in cell cycle regulation. In mammalian cells, CDK1, with its partners cyclin A2 and B1, alone can drive the cell cycle. Another one, Cdk5, is involved indirectly as the CDK-activating kinase. Cyclin-CDK complexes phosphorylate substrates appropriate for the particular cell cycle phase. Cyclin-CDK complexes in earlier cell-cycle phase help activate cyclin-CDK complexes in later phases.
Table 2: Cyclins and CDKs by Cell-Cycle Phase
| Phase | Cyclin | CDK |
|---|---|---|
| G0 | C | Cdk3 |
| G1 | D, E | Cdk4, Cdk2, Cdk6 |
| S | A, E | Cdk2 |
| G2 | A | Cdk2, Cdk1 |
| M | B | Cdk1 |
Table 3: Cyclin-dependent kinases that control the cell cycle in model organisms.
| Species | Name | Original name | Size (amino acids) | Function |
|---|---|---|---|---|
| Saccharomyces cerevisiae | Cdk1 | Cdc28 | 298 | All cell-cycle stages |
| Schizosaccharomyces pombe | Cdk1 | Cdc2 | 297 | All cell-cycle stages |
| Drosophila melanogaster | Cdk1 | Cdc2 | 297 | M |
| Cdk2 | Cdc2c | 314 | G1/S, S, possibly M | |
| Cdk4 | Cdk4/6 | 317 | G1, promotes growth | |
| Xenopus laevis | Cdk1 | Cdc2 | 301 | M |
| Cdk2 | 297 | S, possibly M | ||
| Homo sapiens | Cdk1 | Cdc2 | 297 | M |
| Cdk2 | 298 | G1, S, possibly M | ||
| Cdk4 | 301 | G1 | ||
| Cdk6 | 326 | G1 |
A list of CDKs with their regulator protein, cyclin or other.
- CDK1; cyclin A, cyclin B
- CDK2; cyclin A, cyclin E
- CDK3; cyclin C
- CDK4; cyclin D1, cyclin D2, cyclin D3
- CDK5; CDK5R1, CDK5R2. See also CDKL5.
- CDK6; cyclin D1, cyclin D2, cyclin D3
- CDK7; cyclin H
- CDK8; cyclin C
- CDK9; cyclin T1, cyclin T2a, cyclin T2b, cyclin K
- CDK10
- CDK11 (CDC2L2) ; cyclin L
- CDK12 (CRKRS) ; cyclin L
- CDK13 (CDC2L5) ; cyclin L
Read more about this topic: Cyclin-dependent Kinase
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