title: Sgf1p, a new component of the Sec34p/Sec35p complex.
abstract: Here we report the identification of SGF1 as a high-copy suppressor of the sec35-1 mutant. SGF1 encodes an essential hydrophilic protein of approximately 100 kDa. Using the yeast two-hybrid system and coprecipitation studies, we demonstrate that Sgf1p is a new subunit of the multiprotein Sec34p/Sec35p complex. Reduced levels of Sgf1p lead to the accumulation of a variety of membranes as well as a kinetic block in endoplasmic reticulum to Golgi traffic. Immunofluorescence studies demonstrate that Sec34p is found throughout the Golgi, with a high concentration on early Golgi. Although an earlier study suggested that Sec34p (Grd20p) is not required for protein secretion, we show here that the sec34-2 and sec35-1 mutations lead to a pleiotropic block in the secretion of all proteins into the growth medium.
authors.affiliation: Department of Cell Biology and Howard Hughes Medical Institute, Yale University, New Haven, CT, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Kim
authors.forename: T
authors.initials: T
authors.lastname: Massey
authors.forename: M
authors.initials: M
authors.lastname: Sacher
authors.forename: M
authors.initials: M
authors.lastname: Pypaert
authors.forename: S
authors.initials: S
authors.lastname: Ferro-Novick
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002451:Cell Compartmentation; D002462:Cell Membrane; D017931:DNA Primers; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008854:Microscopy, Electron; D016366:Open Reading Frames; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; C112749:COG2 protein, S cerevisiae; C401396:COG3 protein, S cerevisiae; D002352:Carrier Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins