Repression of origin assembly in metaphase depends on inhibition of RLF-B/Cdt1 by geminin.
Repression of origin assembly in metaphase depends on inhibition of RLF-B/Cdt1 by geminin.
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DOI：
10.1038/35055000
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发表时间：
2001-02
影响因子：
21.3
通讯作者：
Blow, J J
中科院分区：
文献类型：
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作者：
Tada, S;Li, A;Maiorano, D;Mechali, M;Blow, J J
真核细胞的复制起点通过装载MCM(2-7)在细胞周期的早期被“许可”进行复制。随着染色质的复制，MCM(2-7)被移除，从而防止原点重新点火。在这里，我们报告了许可系统的RLF-B组件的纯化，并表明它对应于CDT1。RLF-B/CDT1被有丝分裂后期降解的蛋白质Ginin抑制。中期提取液中双黄素的免疫耗竭使他们能够组装获得许可的复制起点。中期抑制CDKs只有在Ginin耗尽后才能刺激起源组装。这些实验表明，在高等真核生物细胞周期的后期，Ginin介导的对RLF-B/CDT1的抑制对于抑制起源组装是必不可少的。
Eukaryotic replication origins are “licensed” for replication early in the cell cycle by loading Mcm(2-7). As chromatin replicates, Mcm(2-7) are removed, thus preventing origin re-firing. Here we report purification of the RLF-B component of the licensing system and show that it corresponds to Cdt1. RLF-B/Cdt1 was inhibited by geminin, a protein that is degraded during late mitosis. Immunodepletion of geminin from metaphase extracts allowed them to assemble licensed replication origins. Inhibition of CDKs in metaphase stimulated origin assembly only after geminin depletion. These experiments suggest that geminin-mediated inhibition of RLF-B/Cdt1 is essential for repressing origin assembly late in the cell cycle of higher eukaryotes.