CDK inactivation is the only essential function of the APC/C and the mitotic exit network proteins for origin resetting during mitosis

Passage through mitosis is required to reset replication origins for the su bsequent S phase. During mitosis, a series of biochemical reactions involvi ng cyclin-dependent kinases (CDKs), the anaphase promoting complex or cyclo some (APC/C), and a mitotic exit network including Cdc5, 14, and 15 coordin ates the proper separation and segregation of sister chromatids. Here we sh ow that cyclin B/CDK inactivation can drive origin resetting in either earl y S phase or mitosis. This origin resetting occurs efficiently in the absen ce of APC/C function and mitotic exit network function. We conclude that CD K inactivation is the single essential event in mitosis required to allow p re-RC assembly for the next cell cycle.