title: Golgi localization of glycosyltransferases requires a Vps74p oligomer.
abstract: The mechanism of glycosyltransferase localization to the Golgi apparatus is a long-standing question in secretory cell biology. All Golgi glycosyltransferases are type II membrane proteins with small cytosolic domains that contribute to Golgi localization. To date, no protein has been identified that recognizes the cytosolic domains of Golgi enzymes and contributes to their localization. Here, we report that yeast Vps74p directly binds to the cytosolic domains of cis and medial Golgi mannosyltransferases and that loss of this interaction correlates with loss of Golgi localization of these enzymes. We have solved the X-ray crystal structure of Vps74p and find that it forms a tetramer, which we also observe in solution. Deletion of a critical structural motif disrupts tetramer formation and results in loss of Vps74p localization and function. Vps74p is highly homologous to the human GMx33 Golgi matrix proteins, suggesting a conserved function for these proteins in the Golgi enzyme localization machinery.
authors.affiliation: Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Karl R
authors.initials: KR
authors.lastname: Schmitz
authors.forename: Jingxuan
authors.initials: J
authors.lastname: Liu
authors.forename: Shiqing
authors.initials: S
authors.lastname: Li
authors.forename: Thanuja Gangi
authors.initials: TG
authors.lastname: Setty
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Wood
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Burd
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Ferguson
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006031:Glycosylation; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000737:chemistry / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018832:Molecular Chaperones; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C528905:Vps74 protein, S cerevisiae; D016695:Glycosyltransferases