Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
The checkpoint kinase Chk1 undergoes ATR-mediated phosphorylation and activation in response to unreplicated DNA, but the precise mechanism of Chk1 activation is not known. In this study, we have analyzed the domain structure of Xenopus Chk1 and explored the mechanism of its activation by ATR-mediated phosphorylation. We show that the C-terminal region of Xenopus Chk1 contains an autoinhibitory region (AIR), which largely overlaps with a bipartite, unusually long ( approximately 85-amino acid) nuclear localization signal. When coexpressed in oocytes or embryos, the AIR can interact with and inhibit the kinase domain of Chk1, but not full-length Chk1, suggesting an autoinhibitory intramolecular interaction in the Chk1 molecule. If linked with the preceding ATR phosphorylation domain that has either phospho-mimic mutation or genuine phosphorylation, however, the AIR can no longer interact with or inhibit the kinase domain, suggesting a conformational change of the AIR by ATR-mediated phosphorylation. Even in full-length Chk1, such phospho-mimic mutation can interfere with the autoinhibitory intramolecular interaction, but only if this interaction is somewhat weakened by an additional mutation in the AIR. These results provide significant insights into the mechanism of Chk1 activation at the DNA replication checkpoint.
Abraham,
Cell cycle checkpoint signaling through the ATM and ATR kinases.
2001, Pubmed
Abraham,
Cell cycle checkpoint signaling through the ATM and ATR kinases.
2001,
Pubmed
Barlow,
Atm-deficient mice: a paradigm of ataxia telangiectasia.
1996,
Pubmed
Bartek,
Chk1 and Chk2 kinases in checkpoint control and cancer.
2003,
Pubmed
Capasso,
Phosphorylation activates Chk1 and is required for checkpoint-mediated cell cycle arrest.
2002,
Pubmed
,
Xenbase
Chen,
Association of Chk1 with 14-3-3 proteins is stimulated by DNA damage.
1999,
Pubmed
Chen,
The 1.7 A crystal structure of human cell cycle checkpoint kinase Chk1: implications for Chk1 regulation.
2000,
Pubmed
Conti,
Crystallographic analysis of the recognition of a nuclear localization signal by the nuclear import factor karyopherin alpha.
1998,
Pubmed
Dasso,
Completion of DNA replication is monitored by a feedback system that controls the initiation of mitosis in vitro: studies in Xenopus.
1990,
Pubmed
,
Xenbase
Dingwall,
Nuclear targeting sequences--a consensus?
1991,
Pubmed
Fogarty,
The Drosophila grapes gene is related to checkpoint gene chk1/rad27 and is required for late syncytial division fidelity.
1997,
Pubmed
Furuno,
Suppression of DNA replication via Mos function during meiotic divisions in Xenopus oocytes.
1994,
Pubmed
,
Xenbase
Gatei,
Ataxia-telangiectasia-mutated (ATM) and NBS1-dependent phosphorylation of Chk1 on Ser-317 in response to ionizing radiation.
2003,
Pubmed
Guo,
Requirement for Atr in phosphorylation of Chk1 and cell cycle regulation in response to DNA replication blocks and UV-damaged DNA in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase
Hartwell,
Checkpoints: controls that ensure the order of cell cycle events.
1989,
Pubmed
Jiang,
Regulation of Chk1 includes chromatin association and 14-3-3 binding following phosphorylation on Ser-345.
2003,
Pubmed
Kim,
Substrate specificities and identification of putative substrates of ATM kinase family members.
1999,
Pubmed
Kumagai,
The Xenopus Chk1 protein kinase mediates a caffeine-sensitive pathway of checkpoint control in cell-free extracts.
1998,
Pubmed
,
Xenbase
Kumagai,
Claspin, a novel protein required for the activation of Chk1 during a DNA replication checkpoint response in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase
Kumagai,
Repeated phosphopeptide motifs in Claspin mediate the regulated binding of Chk1.
2003,
Pubmed
,
Xenbase
Liu,
Chk1 is an essential kinase that is regulated by Atr and required for the G(2)/M DNA damage checkpoint.
2000,
Pubmed
Lopez-Girona,
Serine-345 is required for Rad3-dependent phosphorylation and function of checkpoint kinase Chk1 in fission yeast.
2001,
Pubmed
Lund,
Nonaqueous isolation of transcriptionally active nuclei from Xenopus oocytes.
1990,
Pubmed
,
Xenbase
Matsuoka,
Linkage of ATM to cell cycle regulation by the Chk2 protein kinase.
1998,
Pubmed
Mattaj,
Nucleocytoplasmic transport: the soluble phase.
1998,
Pubmed
Nakajo,
Involvement of Chk1 kinase in prophase I arrest of Xenopus oocytes.
1999,
Pubmed
,
Xenbase
Nurse,
Checkpoint pathways come of age.
1997,
Pubmed
Oe,
Cytoplasmic occurrence of the Chk1/Cdc25 pathway and regulation of Chk1 in Xenopus oocytes.
2001,
Pubmed
,
Xenbase
Okamoto,
The existence of two distinct Wee1 isoforms in Xenopus: implications for the developmental regulation of the cell cycle.
2002,
Pubmed
,
Xenbase
Rhind,
Chk1 and Cds1: linchpins of the DNA damage and replication checkpoint pathways.
2000,
Pubmed
Sanchez,
Conservation of the Chk1 checkpoint pathway in mammals: linkage of DNA damage to Cdk regulation through Cdc25.
1997,
Pubmed
Sarkaria,
Inhibition of ATM and ATR kinase activities by the radiosensitizing agent, caffeine.
1999,
Pubmed
Shann,
Cloning and characterization of liver-specific isoform of Chk1 gene from rat.
2001,
Pubmed
Shiloh,
ATM and ATR: networking cellular responses to DNA damage.
2001,
Pubmed
Shimuta,
Chk1 is activated transiently and targets Cdc25A for degradation at the Xenopus midblastula transition.
2002,
Pubmed
,
Xenbase
Sørensen,
Chk1 regulates the S phase checkpoint by coupling the physiological turnover and ionizing radiation-induced accelerated proteolysis of Cdc25A.
2003,
Pubmed
Walworth,
Fission yeast chk1 protein kinase links the rad checkpoint pathway to cdc2.
1993,
Pubmed
Walworth,
rad-dependent response of the chk1-encoded protein kinase at the DNA damage checkpoint.
1996,
Pubmed
Walworth,
Cell-cycle checkpoint kinases: checking in on the cell cycle.
2000,
Pubmed
Wang,
Activation of Xenopus Chk1 by mutagenesis of threonine-377.
2000,
Pubmed
,
Xenbase
Xu,
Chk2 activation and phosphorylation-dependent oligomerization.
2002,
Pubmed
Yarden,
BRCA1 regulates the G2/M checkpoint by activating Chk1 kinase upon DNA damage.
2002,
Pubmed
Zhao,
ATR-mediated checkpoint pathways regulate phosphorylation and activation of human Chk1.
2001,
Pubmed
Zhou,
The DNA damage response: putting checkpoints in perspective.
2000,
Pubmed
