Cyclin-dependent kinase
From Free net encyclopedia
Cyclin-dependent kinases (CDK) belong to a group of protein kinases originally discovered as being involved in the regulation of the cell cycle. CDK9, however, is an exception, as it plays no role in cell cycle regulation. CDKs are also involved in the regulation of transcription and mRNA processing. CDKs phosphorylate proteins on Serine and Threonine amino acid residues: they are Serine/Threonine kinases. A cyclin-dependent kinase is activated by association with a cyclin forming a cyclin-dependent kinase complex.
A list of CDKs with their regulator protein, cyclin or other.
- CDK1; cyclin A, cyclin B
- CDK2; cyclin A, cyclin E
- CDK3
- CDK4; cyclin D1, D2, D3
- CDK5; p35 (p35 would be another type of regulator that looks only marginally similar to cyclins)
- CDK6; cyclin D1, D2, D3
- CDK7; cyclin H
- CDK8; cyclin C
- CDK9; cyclin T1, T2a, T2b, cyclin K
- CDK10
- CDK11; cyclin L
A cyclin-CDK complex can be regulated by several kinases and phosphatases, including Wee, and CDK-activating kinase (CAK), and Cdc. CAK adds an activating phosphate to the complex, while Wee adds an inhibitory complex; the presence of both activating and inhibitory phosphates renders the complex inactive. Cdc is a phosphatase that removes the inhibitor phosphate added by Wee, rendering the complex active. Cdk feeds back on Wee and Cdc to inhibit and enhance their respective activities.
Leland H. Hartwell, R. Timothy Hunt, and Paul M. Nurse won the 2001 Nobel Prize in Physiology or Medicine for their discovery of cyclin and cyclin-dependent kinase, central molecules in the regulation of the cell cycle.