Figure 1.
Replication licensing and CDK activity through the cell cycle.
A small segment of chromosomal DNA is depicted at different cell cycle stages, with bound (red hexagons, M) or unbound (blue hexagons, M) Mcm2-7. The activity of the replication licensing system (RLS, purple) and cyclin-dependent kinases (CDK, green) at the different stages are show in the central circle. Inset, the sequence of events occurring as each origin binds Mcm2-7 and becomes licensed. The loading of ORC (purple), Cdt1 (yellow) and Cdc6 (green), and then Mcm2-7 (red, M) is shown. At some time after licensing is complete, ORC, Cdc6 and Cdt1 may become inactivated, as indicated by grey shading.
