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.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|