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. MCM5 can form a subcomplex with MCM3. MCM5 also appears to play a role in transcription. MCM5 has been shown to interact with the signal transducer and activator of transcription 1 (STAT1) and demonstrated to be essential for STAT1 target gene transcription.