DNA replication pre-initiation in eukaryotic cells begins with the formation of the pre-replicative complex (pre-RC) during the late M phase and continues in the G1 phase of the mitotic cell cycle, a process also called DNA replication origin licensing. The association of initiation proteins (ORC, Cdc6, Cdt1, Mcm2-7) with the origin of replication in both S. cerevisiae and humans has been demonstrated by chromatin immunoprecipitation experiments. In S. cerevisiae, pre-replicative complexes are assembled from late M to G1. In mammalian cells as well, pre-replicative complexes are assembled from late M to G1, as shown by biochemical fractionation and immunostaining. There are significant sequence similarities among some of the proteins in the pre-replicative complex. The ORC subunits Orc1, Orc4 and Orc5 are homologous to one another and to Cdc6. The six subunits of the Mcm2-7 complex are homologous to one another. In addition, Orc1, Orc4, Orc5, Cdc6, and the Mcm2-7 subunits, are members of the AAA+ superfamily of ATPases. Since the initial identification of these pre-RC components other factors that participate in this complex have been found, including Cdt1 in human, Xenopus, S. pombe, and S. cerevisiae cells.
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Prokhorova, TA, Todorov, IT, Gilbert, DM, Blow, JJ, Dimitrova, DS
Zou-Yang, XH, Stillman, B, Gavin, K, Kobayashi, R, Hunt, T, Pappin, D, Canas, B, Tugal, T
Nasmyth, K, Tanaka, T, Knapp, D
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