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J Cell Biol January 13, 1997; 136 (1): 125-35.

Cell cycle regulation of the replication licensing system: involvement of a Cdk-dependent inhibitor.

Mahbubani HM , Chong JP , Chevalier S , Thömmes P , Blow JJ .

The replication licensing factor (RLF) is an essential initiation factor that is involved in preventing re-replication of chromosomal DNA in a single cell cycle. In Xenopus egg extracts, it can be separated into two components: RLF-M, a complex of MCM/P1 polypeptides, and RLF-B, which is currently unpurified. In this paper we investigate variations in RLF activity throughout the cell cycle. Total RLF activity is low in metaphase, due to a lack of RLF-B activity and the presence of an RLF inhibitor. RLF-B is rapidly activated on exit from metaphase, and then declines during interphase. The RLF inhibitor present in metaphase extracts is dependent on the activity of cyclin-dependent kinases (Cdks). Affinity depletion of Cdks from metaphase extracts removed the RLF inhibitor, while Cdc2/cyclin B directly inhibited RLF activity. In metaphase extracts treated with the protein kinase inhibitor 6-dimethylaminopurine (6-DMAP), both cyclin B and the RLF inhibitor were stabilized although the extracts morphologically entered interphase. These results are consistent with studies in other organisms that invoke a key role for Cdks in preventing re-replication of DNA in a single cell cycle.

PubMed ID: 9008708
PMC ID: PMC2132454
Article link:

Species referenced: Xenopus
Genes referenced: cdkn1a mmut rlf

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References [+] :
Blow, Replication of purified DNA in Xenopus egg extract is dependent on nuclear assembly. 1990, Pubmed, Xenbase