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Updated: Sep 7, 2026

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
Published on: September 17, 2012
Formation of a preinitiation complex by S-phase cyclin CDK-dependent loading of Cdc45p onto chromatin
1Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Abstract:
Cdc45p, a protein essential for initiation of DNA replication, associates with chromatin after "start" in late G1 and during the S phase of the cell cycle. Binding of Cdc45p to chromatin depends on Clb-Cdc28 kinase activity as well as functional Cdc6p and Mcm2p, which suggests that Cdc45p associates with the prereplication complex after activation of S-phase cyclin-dependent kinases (CDKs). As indicated by the timing and the CDK dependence, binding of Cdc45p to chromatin is crucial for commitment to initiation of DNA replication. During S phase, Cdc45p physically interacts with minichromosome maintenance (MCM) proteins on chromatin; however, dissociation of Cdc45p from chromatin is slower than that of MCMs, which indicates that the proteins are released by different mechanisms.
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