title: Analysis of COPII Vesicles Indicates a Role for the Emp47-Ssp120 Complex in Transport of Cell Surface Glycoproteins.
abstract: Coat protein complex II (COPII) vesicle formation at the endoplasmic reticulum (ER) transports nascent secretory proteins forward to the Golgi complex. To further define the machinery that packages secretory cargo and targets vesicles to Golgi membranes, we performed a comprehensive proteomic analysis of purified COPII vesicles. In addition to previously known proteins, we identified new vesicle proteins including Coy1, Sly41 and Ssp120, which were efficiently packaged into COPII vesicles for trafficking between the ER and Golgi compartments. Further characterization of the putative calcium-binding Ssp120 protein revealed a tight association with Emp47 and in emp47Δ cells Ssp120 was mislocalized and secreted. Genetic analyses demonstrated that EMP47 and SSP120 display identical synthetic positive interactions with IRE1 and synthetic negative interactions with genes involved in cell wall assembly. Our findings support a model in which the Emp47-Ssp120 complex functions in transport of plasma membrane glycoproteins through the early secretory pathway.
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Margulis
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Wilson
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Bentivoglio
authors.affiliation: Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA.|Present address: Singer Instruments, Roadwater, Watchet, Somerset, TA23 0RE, UK.
authors.forename: Nripesh
authors.initials: N
authors.lastname: Dhungel
authors.affiliation: Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Gitler
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Barlowe
mesh_terms: D022181:COP-Coated Vesicles / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D055571:Secretory Pathway; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C096914:EMP47 protein, S cerevisiae; D006023:Glycoproteins; D008562:Membrane Glycoproteins; C071940:SSP120 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C082863:IRE1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases
keywords: COPII coat; Golgi; cargo receptors; endoplasmic reticulum; protein secretion; protein trafficking; vesicle budding