title: High confidence proteomic analysis of yeast LDs identifies additional droplet proteins and reveals connections to dolichol synthesis and sterol acetylation.
abstract: Accurate protein inventories are essential for understanding an organelle's functions. The lipid droplet (LD) is a ubiquitous intracellular organelle with major functions in lipid storage and metabolism. LDs differ from other organelles because they are bounded by a surface monolayer, presenting unique features for protein targeting to LDs. Many proteins of varied functions have been found in purified LD fractions by proteomics. While these studies have become increasingly sensitive, it is often unclear which of the identified proteins are specific to LDs. Here we used protein correlation profiling to identify 35 proteins that specifically enrich with LD fractions of Saccharomyces cerevisiae Of these candidates, 30 fluorophore-tagged proteins localize to LDs by microscopy, including six proteins, several with human orthologs linked to diseases, which we newly identify as LD proteins (Cab5, Rer2, Say1, Tsc10, YKL047W, and YPR147C). Two of these proteins, Say1, a sterol deacetylase, and Rer2, a cis-isoprenyl transferase, are enzymes involved in sterol and polyprenol metabolism, respectively, and we show their activities are present in LD fractions. Our results provide a highly specific list of yeast LD proteins and reveal that the vast majority of these proteins are involved in lipid metabolism.
authors.affiliation: Department of Biochemistry and Biophysics University of California, San Francisco, CA 94158 Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158.
authors.forename: Erin
authors.initials: E
authors.lastname: Currie
authors.affiliation: Department of Cell Biology, Yale University, New Haven, CT 06520.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Cell Biology, Yale University, New Haven, CT 06520.
authors.forename: Romain
authors.initials: R
authors.lastname: Christiano
authors.affiliation: Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158.
authors.forename: Chandramohan
authors.initials: C
authors.lastname: Chitraju
authors.affiliation: Department of Cell Biology, Yale University, New Haven, CT 06520.
authors.forename: Nora
authors.initials: N
authors.lastname: Kory
authors.affiliation: Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Harrison
authors.affiliation: Department of Biochemistry and Biophysics University of California, San Francisco, CA 94158 Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158.
authors.forename: Joel
authors.initials: J
authors.lastname: Haas
authors.affiliation: Department of Cell Biology, Yale University, New Haven, CT 06520.
authors.forename: Tobias C
authors.initials: TC
authors.lastname: Walther
authors.affiliation: Department of Biochemistry and Biophysics University of California, San Francisco, CA 94158 Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158 Department of Medicine, University of California, San Francisco, CA 94158.
authors.forename: Robert V
authors.initials: RV
authors.lastname: Farese
mesh_terms: D000107:Acetylation; D004286:Dolichols / Q000096:biosynthesis* / Q000235:genetics; D066292:Lipid Droplets / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism*
chemical_list: D004286:Dolichols; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols
keywords: lipid droplets; lipid metabolism; lipids; polyprenol synthesis; protein targeting