Cyclin

Cyclins are proteins that play a key role in the control of the cell cycle. You are able to with cyclin -dependent kinases to form (CDKs ) complexes and to activate their kinase function. As Cyclinkonzentration is in contrast to the concentration of the Cdks regulate cell cycle -dependent, in turn, these proteins function as regulators of the cyclin-dependent kinases.

Function

Cyclins play a role in different parts of the cell cycle by activation of different cyclin -dependent kinases and associated phosphorylation of various substrates. Cyclin D is present in varying concentrations throughout the cell cycle. The transition from G1 phase to S phase is also determined by cyclin E. Increasing concentration of cyclin A directs the cell in the G2 phase, whereas cyclin B is essential for the start of mitosis. In addition, some so-called " orphan cyclins " are known, could be found for which no associated cyclin -dependent kinase.

For the discovery of cyclins and cyclin -dependent kinases as key factors in the regulation of the cell cycle were 2001 Leland H. Hartwell, Tim Hunt and Paul M. Nurse the Nobel Prize in Physiology or Medicine.