Involved in regulation of DNA replication. Dissociates the MCM complex and inhibits the MCM helicase activity, suggesting that it may function as a helicase loader. Binds to both specific and random double-stranded or single-stranded DNA. Interacts with MCM. The N-terminal AAA+ ATPase domain and the C-terminal winged-helix (WH) domain are both required for DNA binding. Autophosphorylated on a serine. Phosphorylation is inhibited by binding to MCM. Both single-stranded DNA and double-stranded DNA inhibit the phosphorylation reaction. Belongs to the CDC6/cdc18 family.