title: The seipin complex Fld1/Ldb16 stabilizes ER-lipid droplet contact sites.
abstract: Lipid droplets (LDs) are storage organelles consisting of a neutral lipid core surrounded by a phospholipid monolayer and a set of LD-specific proteins. Most LD components are synthesized in the endoplasmic reticulum (ER), an organelle that is often physically connected with LDs. How LD identity is established while maintaining biochemical and physical connections with the ER is not known. Here, we show that the yeast seipin Fld1, in complex with the ER membrane protein Ldb16, prevents equilibration of ER and LD surface components by stabilizing the contact sites between the two organelles. In the absence of the Fld1/Ldb16 complex, assembly of LDs results in phospholipid packing defects leading to aberrant distribution of lipid-binding proteins and abnormal LDs. We propose that the Fld1/Ldb16 complex facilitates the establishment of LD identity by acting as a diffusion barrier at the ER-LD contact sites.
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Grippa
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Buxó
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Mora
authors.affiliation: Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
authors.forename: Charlotta
authors.initials: C
authors.lastname: Funaya
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Fatima-Zahra
authors.initials: FZ
authors.lastname: Idrissi
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mancuso
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Gomez
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.
authors.forename: Júlia
authors.initials: J
authors.lastname: Muntanyà
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Eduard
authors.initials: E
authors.lastname: Sabidó
authors.affiliation: Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain pedro.carvalho@crg.eu.
authors.forename: Pedro
authors.initials: P
authors.lastname: Carvalho
mesh_terms: D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000502:physiology*; D066292:Lipid Droplets / Q000378:metabolism*; D008565:Membrane Proteins / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000502:physiology*; D010743:Phospholipids / Q000096:biosynthesis; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
chemical_list: C527368:Fld1 protein, S cerevisiae; D044388:GTP-Binding Protein gamma Subunits; C000594798:LDB16 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; C554737:seipin protein, S cerevisiae