Gene Engineering Division – DNA BANK –

G1-S trasition

Summary of Cyclin function that regulates G1-S trasitionCyclin Ds are upregulated in response to Ras-Map kinase signalling and assembled with cyclin D-dependent kinases (CDKs). The CDKs initiate Rb phosphorylation, releasing E2F from negative constraints and facilitating activation of a series of E2F-responsive genes, the products of which are necessary for S-phase entry. Activation of cyclin E by E2F enables formation of the cyclin E-cdk2 complex. This is accelerated by the continued sequestration of Cip/Kip proteins into complexes with assembling cyclin D-cdk complexes. Cyclin E-cdk2 completes the phosphorylation of Rb, further enabling activation of E2F-responsive genes, including cyclin A. Cyclin E-Cdk2 also stimulates DNA synthesis presumably by facilitating origin firing through Cdc45-dependent loading of DNA polymerase and promoting histone biosynthesis through direct phosphorylation of NPAT, a factor required for histone transcription. (Contributed by Dr. Koji Nakade)

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Reporters

• Fucci cell cycle indicators

List of gene resources

(GSB0008e, T.M. 2004.04.07)

2018.09.24