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J Biol Chem 2011 Apr 01;28613:11855-64. doi: 10.1074/jbc.M110.199521.
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MCM2-7 form double hexamers at licensed origins in Xenopus egg extract.

Gambus A , Khoudoli GA , Jones RC , Blow JJ .

In late mitosis and G1, Mcm2-7 are assembled onto replication origins to license them for initiation in the upcoming S phase. After initiation, Mcm2-7 provide helicase activity to unwind DNA at the replication fork. Here we examine the structure of Mcm2-7 on chromatin in Xenopus egg extracts. We show that prior to replication initiation, Mcm2-7 is present at licensed replication origins in a complex with a molecular mass close to double that of the Mcm2-7 hexamer. This complex has approximately stoichiometric quantities of the 6 Mcm2-7 proteins and we conclude that it consists of a double heterohexamer. This provides a configuration potentially capable of initiating a pair of bidirectional replication forks in S phase. We also show that after initiation, Mcm2-7 associate with Cdc45 and GINS to form a relatively stable CMG (Cdc45-MCM-GINS) complex. The CMG proteins also associate less strongly with other replication proteins, consistent with the idea that a single CMG complex forms the core of the replisome.

PubMed ID: 21282109
PMC ID: PMC3064236
Article link: J Biol Chem
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: cdc45 cdc7 cdkn1b mcm2 mcm3 mcm4 mmut wdhd1

Article Images: [+] show captions
References [+] :
Aparicio, The human GINS complex associates with Cdc45 and MCM and is essential for DNA replication. 2009, Pubmed, Xenbase