Abstract
The Saccharomyces cerevisiae open reading frame YFR003c encodes a small (155-amino acid) hydrophilic protein that we identified as a novel, heat-stable inhibitor of type 1 protein phosphatase (Ypi1). Ypi1 interacts physically in vitro with both Glc7 and Ppz1 phosphatase catalytic subunits, as shown by pull-down assays. Ypi1 inhibits Glc7 but appears to be less effective toward Ppz1 phosphatase activity under the conditions tested. Ypi1 contains a 48RHNVRW53 sequence, which resembles the characteristic consensus PP1 phosphatase binding motif. A W53A mutation within this motif abolishes both binding to and inhibition of Glc7 and Ppz1 phosphatases. Deletion of YPI1 is lethal, suggesting a relevant role of the inhibitor in yeast physiology. Cells overexpressing Ypi1 display a number of phenotypes consistent with an inhibitory role of this protein on Glc7, such as decreased glycogen content and an increased growth defect in a slt2/mpk1 mitogen-activated protein kinase-deficient background. Taking together, these results define Ypi1 as the first inhibitory subunit of Glc7 identified in budding yeast.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Catalytic Domain
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Dose-Response Relationship, Drug
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Escherichia coli / metabolism
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Gene Deletion
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Glutathione Transferase / metabolism
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Glycogen / chemistry
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Immunoblotting
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Intracellular Signaling Peptides and Proteins
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Mitogen-Activated Protein Kinases*
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Molecular Sequence Data
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Mutation
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Oligonucleotides / chemistry
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Phenotype
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Phosphoprotein Phosphatases / antagonists & inhibitors*
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Phosphoprotein Phosphatases / chemistry
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Phosphorylation
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Phylogeny
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Plasmids / metabolism
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Protein Binding
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Protein Phosphatase 1
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Recombinant Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / genetics*
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Temperature
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Time Factors
Substances
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Intracellular Signaling Peptides and Proteins
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Oligonucleotides
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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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Glycogen
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Glutathione Transferase
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Mitogen-Activated Protein Kinases
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SLT2 protein, S cerevisiae
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GLC7 protein, S cerevisiae
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PPZ1 protein, S cerevisiae
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Phosphoprotein Phosphatases
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Protein Phosphatase 1