The MCM (Mini-Chromosome Maintenance) complex is a key component of the pre-replication complex involved in replication licensing which restricts DNA replication to only once per cell cycle. The MCM complex is a heterohexamer of MCM2, MCM3, MCM4, MCM5, MCM6, and MCM7. MCM2 interacts with the core MCM complex (MCM4, 6, and 7) to regulate its helicase activity.