title: PtdIns4P recognition by Vps74/GOLPH3 links PtdIns 4-kinase signaling to retrograde Golgi trafficking.
abstract: Targeting and retention of resident integral membrane proteins of the Golgi apparatus underly the function of the Golgi in glycoprotein and glycolipid processing and sorting. In yeast, steady-state Golgi localization of multiple mannosyltransferases requires recognition of their cytosolic domains by the peripheral Golgi membrane protein Vps74, an orthologue of human GOLPH3/GPP34/GMx33/MIDAS (mitochondrial DNA absence sensitive factor). We show that targeting of Vps74 and GOLPH3 to the Golgi apparatus requires ongoing synthesis of phosphatidylinositol (PtdIns) 4-phosphate (PtdIns4P) by the Pik1 PtdIns 4-kinase and that modulation of the levels and cellular location of PtdIns4P leads to mislocalization of these proteins. Vps74 and GOLPH3 bind specifically to PtdIns4P, and a sulfate ion in a crystal structure of GOLPH3 indicates a possible phosphoinositide-binding site that is conserved in Vps74. Alterations in this site abolish phosphoinositide binding in vitro and Vps74 function in vivo. These results implicate Pik1 signaling in retention of Golgi-resident proteins via Vps74 and show that GOLPH3 family proteins are effectors of Golgi PtdIns 4-kinases.
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Wood
authors.forename: Karl R
authors.initials: KR
authors.lastname: Schmitz
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Bessman
authors.forename: Thanuja Gangi
authors.initials: TG
authors.lastname: Setty
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Ferguson
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Burd
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006056:Golgi Apparatus / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D002352:Carrier Proteins; C429024:GOLPH3 protein, human; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D029701:Saccharomyces cerevisiae Proteins; C528905:Vps74 protein, S cerevisiae; C037178:phosphatidylinositol 4-phosphate; D019870:1-Phosphatidylinositol 4-Kinase