DNA Replication Apparatus and S-Phase Checkpoint Control

点击翻译按钮获取中文摘要

Saccharomyces cerevisiae Cdc7/Dbf4 protein kinase, which regulates the initiation of chromosomal DNA replication, was expressed and purified from insect cells. It was found that the purified Cdc:7/Dbf4 phosphorylates Mcm2, which is one of Mcm2-7 complex. Furthermore, its phosphorylation sites were determined. Xenopus homologs of S. cerevisiae Cdc7/Dbf4 protein Kinase and Mcm10 were identified and their corresponding genes were cloned. it was found that Xenopus Cdc7/Dbf4.protein kinase and Mcm10 are required for the initiation of chromosomal DNA replication as in S. cerevisiae.S. cerevisiae Rad53p, which involved in both DNA-damage-and S-phase checkpoint regulation, was purified and one of the substrates was identified to be Dbf4/Cdc7 protein kinase. It was found that Rad53p directly intercts with Cdc7/Dbf4 and phosphorylates Dbf4. Phosphorylation of Cdc7/Dbf4 complex with Rad53p inactivates Cdc7/Dbf4 protein kinase activity.