CYCLIN-DEPENDENT KINASE AND INITIATION AT EUKARYOTIC ORIGINS - A REPLICATION SWITCH

A growing body of evidence indicates that cyclin-dependent kinases (CD Ks) regulate the activity of eukaryotic origins of replication both po sitively and negatively. Although the details of this control remain u nclear, recent work suggests that CDKs act directly at origins, where they associate with and phosphorylate several key initiator proteins. These data suggest that a CDK-regulated replication switch operates at each origin to ensure that initiation occurs precisely once per cell cycle.