Cell cycle control of eukaryotic DNA replication

A clearer picture of replication control is emerging through the characterization of proteins, such as cdc18/Cdc6 and members of the mini-chromosome maintenance (MCM) protein family, that are involved in the initiation step. Cyclin B dependent kinases have conserved roles in both Saccharomyces cerevisiae and Schizosaccharomyces pombe, switching on DNA replication in G(1) and preventing re-replication in G(2). A model is suggested where MCMs and CDKs play complementary roles to ensure 'once-per-cell-cycle' replication, with CDKs maintaining a G(1) or GP State, whereas MCMs provide a cis-acting control on chromatin to prevent reinitiation during a single S phase.