Abstract
The order and fidelity of cell cycle events in mammals is intimately linked to the integrity of the Chk1 kinase-Cdc25A phosphatase pathway. Chk1 phosphorylation targets Cdc25A for destruction and, as shown here, inhibits interactions between Cdc25A and its mitotic substrate cyclin B1-Cdk1. Phosphorylation of Cdc25A on serine 178 and threonine 507 facilitates 14-3-3 binding, and Chk1 phosphorylates both residues in vitro. Mutation of T507 to alanine (T507A) enhanced the biological activity of Cdc25A. Cdc25A(T507A) was more efficient in binding to cyclin B1, activating cyclin B1-Cdk1, and promoting premature entry into mitosis. We propose that the Chk1/Cdc25A/14-3-3 pathway functions to prevent cells from entering into mitosis prior to replicating their genomes to ensure the fidelity of the cell division process.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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14-3-3 Proteins
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Amino Acid Sequence
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Animals
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Cell Line
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Checkpoint Kinase 1
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Cyclin B / genetics
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Cyclin B / metabolism
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Cyclin B1
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DNA Replication
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Humans
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Mitosis / physiology*
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Molecular Sequence Data
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Phosphorylation
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Protein Binding
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Serine / metabolism
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Threonine / metabolism
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Tyrosine 3-Monooxygenase / genetics
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Tyrosine 3-Monooxygenase / metabolism*
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cdc25 Phosphatases / genetics
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cdc25 Phosphatases / metabolism*
Substances
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14-3-3 Proteins
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CCNB1 protein, human
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Cyclin B
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Cyclin B1
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Recombinant Fusion Proteins
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Threonine
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Serine
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Tyrosine 3-Monooxygenase
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Protein Kinases
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CHEK1 protein, human
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Checkpoint Kinase 1
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CDC25A protein, human
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cdc25 Phosphatases