of the Mcm2-7 complex firmly anchor onto the surfaces created by the ORC-Cdc6 ring structure around origin DNA. The fusion of the two head-to-head Mcm2-7 hexamers is believed to be facilitated by the removal of Cdt1, leaving the NTDs of the two MCM hexamers flexible for inter-ring interactions. The loading of MCM2-7 onto DNA is an active process that requires ATP hydrolysis by both Orc1-6 and Cdc6. This process is coined "Replication Licensing" as it is a prerequisite for DNA replication initiation in every cell division cycle.

Late G1/early S - initiation