Abstract
We have recently characterized Ypi1 as an inhibitory subunit of yeast Glc7 PP1 protein phosphatase. In this work we demonstrate that Ypi1 forms a complex with Glc7 and Sds22, another Glc7 regulatory subunit that targets the phosphatase to substrates involved in cell cycle control. Interestingly, the combination of equimolar amounts of Ypi1 and Sds22 leads to an almost full inhibition of Glc7 activity. Because YPI1 is an essential gene, we have constructed conditional mutants that demonstrate that depletion of Ypi1 leads to alteration of nuclear localization of Glc7 and cell growth arrest in mid-mitosis with aberrant mitotic spindle. These phenotypes mimic those produced upon inactivation of Sds22. The fact that progressive depletion of either Ypi1 or Sds22 resulted in similar physiological phenotypes and that both proteins inhibit the phosphatase activity of Glc7 strongly suggest a common role of these two proteins in regulating Glc7 nuclear localization and function.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Nucleus / enzymology*
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DNA Primers
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Enzyme Inhibitors
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Escherichia coli / enzymology
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Escherichia coli / genetics
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Genotype
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Intracellular Signaling Peptides and Proteins
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Mitosis
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Molecular Sequence Data
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Nuclear Proteins / metabolism*
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Phosphoprotein Phosphatases / antagonists & inhibitors
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Phosphoprotein Phosphatases / genetics
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Phosphoprotein Phosphatases / metabolism*
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Plasmids
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Protein Phosphatase 1
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Recombinant Proteins / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins / antagonists & inhibitors
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Spindle Apparatus / genetics
Substances
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DNA Primers
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Enzyme Inhibitors
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Intracellular Signaling Peptides and Proteins
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Nuclear Proteins
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Recombinant Proteins
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Saccharomyces cerevisiae Proteins
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Ypi1 protein, S cerevisiae
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GLC7 protein, S cerevisiae
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Phosphoprotein Phosphatases
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Protein Phosphatase 1
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SDS22 protein, S cerevisiae