PtdIns4P recognition by Vps74/GOLPH3 links PtdIns 4-kinase signaling to retrograde Golgi trafficking.
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.
Wood
Christopher S
CS
Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
Schmitz
Karl R
KR
Bessman
Nicholas J
NJ
Setty
Thanuja Gangi
TG
Ferguson
Kathryn M
KM
Burd
Christopher G
CG
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
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