title: Synthetic genetic array analysis of the PtdIns 4-kinase Pik1p identifies components in a Golgi-specific Ypt31/rab-GTPase signaling pathway.
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.
authors.affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, School of Medicine, University of California at San Diego, La Jolla, CA 92093-0668, USA.
authors.forename: Vicki A
authors.initials: VA
authors.lastname: Sciorra
authors.forename: Anjon
authors.initials: A
authors.lastname: Audhya
authors.forename: Ainslie B
authors.initials: AB
authors.lastname: Parsons
authors.forename: Nava
authors.initials: N
authors.lastname: Segev
authors.forename: Charles
authors.initials: C
authors.lastname: Boone
authors.forename: Scott D
authors.initials: SD
authors.lastname: Emr
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015153:Blotting, Western; D002687:Chitin Synthase; D020690:GTPase-Activating Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D046228:Microarray Analysis; D018613:Microscopy, Confocal; D008954:Models, Biological; D009154:Mutation; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D050683:R-SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction; D013696:Temperature; D033921:Vesicular Transport Proteins / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; C482449:Gyp2 protein, S cerevisiae; D008565:Membrane Proteins; D050683:R-SNARE Proteins; C083242:SNC2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C475918:TRS130 protein, S cerevisiae; C080595:TRS65 protein, S cerevisiae; D033921:Vesicular Transport Proteins; C406327:transport protein particle, TRAPP; D049452:Green Fluorescent Proteins; C069390:CHS3 protein, S cerevisiae; D002687:Chitin Synthase; D019870:1-Phosphatidylinositol 4-Kinase; C441760:PIK1 protein, S cerevisiae; D020691:rab GTP-Binding Proteins