Abstract
The spindle assembly checkpoint inhibits anaphase until all chromosomes have become attached to the mitotic spindle. A complex between the checkpoint proteins Mad1 and Mad2 provides a platform for Mad2:Mad2 dimerization at unattached kinetochores, which enables Mad2 to delay anaphase. Here, we show that mutations in Bub1 and within the Mad1 C-terminal domain impair the kinetochore localization of Mad1:Mad2 and abrogate checkpoint activity. Artificial kinetochore recruitment of Mad1 in these mutants co-recruits Mad2; however, the checkpoint remains non-functional. We identify specific mutations within the C-terminal head of Mad1 that impair checkpoint activity without affecting the kinetochore localization of Bub1, Mad1 or Mad2. Hence, Mad1 potentially in conjunction with Bub1 has a crucial role in checkpoint signalling in addition to presenting Mad2.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Cell Cycle Proteins / chemistry
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Kinetochores / metabolism*
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M Phase Cell Cycle Checkpoints*
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Mad2 Proteins / genetics
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Mad2 Proteins / metabolism*
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Molecular Sequence Data
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Protein Binding
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Protein Serine-Threonine Kinases / chemistry
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism
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Protein Structure, Tertiary
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Schizosaccharomyces / genetics
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Schizosaccharomyces / metabolism*
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Schizosaccharomyces pombe Proteins / chemistry
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Signal Transduction
Substances
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Cell Cycle Proteins
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Mad2 Proteins
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Nuclear Proteins
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Schizosaccharomyces pombe Proteins
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mad1 protein, S pombe
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mad2 protein, S pombe
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Bub1 protein, S pombe
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Protein Serine-Threonine Kinases