Involved in regulation of DNA replication. May play an essential role in origin recognition. Binds to DNA, with a preference for origin-specific double-stranded sequences. Does not bind single-stranded DNA. Inhibits MCM helicase activity but does not affect its oligomeric state. Monomer. Interacts with MCM via the WH domain. 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 stimulated by binding to MCM. Both single-stranded DNA and double-stranded DNA inhibit the phosphorylation reaction. Belongs to the CDC6/cdc18 family.