Abstract
Cdc20, an activator of the anaphase-promoting complex (APC), is also required for the exit from mitosis in Saccharomyces cerevisiae. Here we show that during mitosis, both the inactivation of Cdc28-Clb2 kinase and the degradation of mitotic cyclin Clb2 occur in two steps. The first phase of Clb2 proteolysis, which commences at the metaphase-to-anaphase transition when Clb2 abundance is high, is dependent on Cdc20. The second wave of Clb2 destruction in telophase requires activation of the Cdc20 homolog, Hct1/Cdh1. The first phase of Clb2 destruction, which lowers the Cdc28-Clb2 kinase activity, is a prerequisite for the second. Thus, Clb2 proteolysis is not solely mediated by Hct1 as generally believed; instead, it requires a sequential action of both Cdc20 and Hct1.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anaphase / physiology
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Anaphase-Promoting Complex-Cyclosome
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CDC28 Protein Kinase, S cerevisiae / metabolism*
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Cdc20 Proteins
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Cdh1 Proteins
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cyclin B / metabolism*
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Fungal Proteins
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GTP-Binding Proteins / genetics
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Ligases / metabolism
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Mitosis / physiology*
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins*
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Telophase / physiology
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Ubiquitin-Protein Ligase Complexes*
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Ubiquitin-Protein Ligases
Substances
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CDC15 protein
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CDC20 protein, S cerevisiae
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CDH1 protein, S cerevisiae
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CLB2 protein, S cerevisiae
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CLB5 protein, S cerevisiae
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Cdc20 Proteins
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Cdh1 Proteins
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Cell Cycle Proteins
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Cyclin B
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Fungal Proteins
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Saccharomyces cerevisiae Proteins
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Ubiquitin-Protein Ligase Complexes
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Anaphase-Promoting Complex-Cyclosome
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Ubiquitin-Protein Ligases
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CDC28 Protein Kinase, S cerevisiae
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GTP-Binding Proteins
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Ligases