Abstract
Production of the essential phospholipid PI4P at the Golgi by the Pik1 kinase is required for protein secretion, while a distinct pool of PI4P generated by the Stt4 kinase is critical for normal actin cytoskeleton organization. We identify a transmembrane protein that stabilizes Stt4 at the plasma membrane where it directs synthesis of PI4P, which is required for activation of the Rho1/Pkc1-mediated MAP kinase cascade. Inactivation of Stt4 or the PI4P 5-kinase Mss4 results in mislocalization of the Rho-GTPase GEF Rom2. Rom2 binds PI4,5P(2) through its PH domain and represents the first identified effector in the Stt4-Mss4 pathway. Based on these results, we propose that Stt4-Mss4 generates PI4,5P(2) at the plasma membrane, required to recruit/activate effector proteins such as Rom2.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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1-Phosphatidylinositol 4-Kinase / genetics
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1-Phosphatidylinositol 4-Kinase / metabolism*
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Cell Membrane / metabolism
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Enzyme Activation
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Fungal Proteins / metabolism*
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Genes, Fungal
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Genes, Suppressor
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Mitogen-Activated Protein Kinases / metabolism*
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Models, Biological
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Phosphatidylinositol 4,5-Diphosphate
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Phosphatidylinositol Phosphates / metabolism
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Phosphotransferases (Alcohol Group Acceptor)
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Phosphotransferases*
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Protein Kinase C
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Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
Substances
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Fungal Proteins
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Phosphatidylinositol 4,5-Diphosphate
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Phosphatidylinositol Phosphates
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Proteins
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Saccharomyces cerevisiae Proteins
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phosphatidylinositol 4-phosphate
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Phosphotransferases
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Phosphotransferases (Alcohol Group Acceptor)
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Pkc1 protein, Trichoderma reesei
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1-Phosphatidylinositol 4-Kinase
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PIK1 protein, S cerevisiae
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STT4 protein, S cerevisiae
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MSS4 protein, S cerevisiae
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Protein Kinase C
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Mitogen-Activated Protein Kinases