Synthetic genetic array analysis of the PtdIns 4-kinase Pik1p identifies components in a Golgi-specific Ypt31/rab-GTPase signaling pathway.

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.
Mesh Terms:
1-Phosphatidylinositol 4-Kinase, Blotting, Western, Chitin Synthase, GTPase-Activating Proteins, Gene Expression Regulation, Enzymologic, Golgi Apparatus, Green Fluorescent Proteins, Membrane Proteins, Microarray Analysis, Microscopy, Confocal, Models, Biological, Mutation, Precipitin Tests, Protein Structure, Tertiary, Protein Transport, R-SNARE Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, Temperature, Vesicular Transport Proteins, rab GTP-Binding Proteins
Mol. Biol. Cell
Date: Feb. 01, 2005
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