Required for DNA synthesis. Required for entry into or completion of S phase. Involved in DNA replication and seems to participate in the activation of the pre-replication complex (pre-RC) and in transcription elongation. May play a role as a key coordinator in assembling the replication fork. Proposed to function at replication origins following the binding of the MCM2-7 complex prior to the recruitment of CDC45. Probably is required to stimulate phosphorylation of the MCM2-7 complex by the CDC7-DBF4 kinase complex. May recruit the DNA polymerase alpha:primase complex to replication origins and is required to maintain it on chromatin independently of CDC45. May also play a role in transcriptional silencing. Self-associates; assembles into large homomultimeric complexes of approximately 800 kDa. Associates with the MCM2-7 complex and the DNA polymerase alpha:primase complex. Interacts with ORC1, ORC2, MCM2, MCM3, CDC54/MCM4, MCM6, CDC47/MCM7, RFA2, CDC45, POL1, PRI2, POL12, SIR2 and SIR3. The diubiquitinated form interacts with POL30/PCNA C-terminus. Colocalizes with ORC1 on chromatin independent from cell cycle. According to PubMed:15494305 is recruited to replication origins in a cell cycle regulated manner. The zinc finger-like domain binds a zinc ion and is involved in self-association. Diubiquitinated in a cell cycle-regulated manner. Ubiquitination first appears in late G(1) and persists throughout S phase. Present with 1860 molecules/cell in log phase SD medium. Belongs to the MCM10 family.