Abstract
Phosphorylated derivatives of phosphatidylinositol are essential regulators of both endocytic and exocytic trafficking in eukaryotic cells. In Saccharomyces cerevisiae, the phosphatidylinositol 4-kinase, Pik1p generates a distinct pool of PtdIns(4)P that is required for normal Golgi structure and secretory function. Here, we utilize a synthetic genetic array analysis of a conditional pik1 mutant to identify candidate components of the Pik1p/PtdIns(4)P signaling pathway at the Golgi. Our data suggest a mechanistic involvement for Pik1p with a specific subset of Golgi-associated proteins, including the Ypt31p rab-GTPase and the TRAPPII protein complex, to regulate protein trafficking through the secretory pathway. We further demonstrate that TRAPPII specifically functions in a Ypt31p-dependent pathway and identify Gyp2p as the first biologically relevant GTPase activating protein for Ypt31p. We propose that multiple stage-specific signals, which may include Pik1p/PtdIns(4)P, TRAPPII and Gyp2p, impinge upon Ypt31 signaling to regulate Golgi secretory function.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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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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1-Phosphatidylinositol 4-Kinase / ultrastructure
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Blotting, Western
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Chitin Synthase
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GTPase-Activating Proteins / metabolism
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Gene Expression Regulation, Enzymologic
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Golgi Apparatus / metabolism*
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Golgi Apparatus / ultrastructure
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Green Fluorescent Proteins / metabolism
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Membrane Proteins / metabolism
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Microarray Analysis*
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Microscopy, Confocal
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Models, Biological
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Mutation
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Precipitin Tests
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Protein Structure, Tertiary
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Protein Transport
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R-SNARE Proteins
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae / ultrastructure
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Saccharomyces cerevisiae Proteins / ultrastructure
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Signal Transduction*
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Temperature
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Vesicular Transport Proteins / metabolism
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rab GTP-Binding Proteins / chemistry
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rab GTP-Binding Proteins / metabolism*
Substances
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GTPase-Activating Proteins
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Gyp2 protein, S cerevisiae
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Membrane Proteins
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R-SNARE Proteins
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SNC2 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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TRS130 protein, S cerevisiae
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TRS65 protein, S cerevisiae
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Vesicular Transport Proteins
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transport protein particle, TRAPP
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Green Fluorescent Proteins
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CHS3 protein, S cerevisiae
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Chitin Synthase
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1-Phosphatidylinositol 4-Kinase
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PIK1 protein, S cerevisiae
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rab GTP-Binding Proteins