title: Requirement for neo1p in retrograde transport from the Golgi complex to the endoplasmic reticulum.
abstract: Neo1p from Saccharomyces cerevisiae is an essential P-type ATPase and potential aminophospholipid translocase (flippase) in the Drs2p family. We have previously implicated Drs2p in protein transport steps in the late secretory pathway requiring ADP-ribosylation factor (ARF) and clathrin. Here, we present evidence that epitope-tagged Neo1p localizes to the endoplasmic reticulum (ER) and Golgi complex and is required for a retrograde transport pathway between these organelles. Using conditional alleles of NEO1, we find that loss of Neo1p function causes cargo-specific defects in anterograde protein transport early in the secretory pathway and perturbs glycosylation in the Golgi complex. Rer1-GFP, a protein that cycles between the ER and Golgi complex in COPI and COPII vesicles, is mislocalized to the vacuole in neo1-ts at the nonpermissive temperature. These phenotypes suggest that the anterograde protein transport defect is a secondary consequence of a defect in a COPI-dependent retrograde pathway. We propose that loss of lipid asymmetry in the cis Golgi perturbs retrograde protein transport to the ER.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235-1634, USA.
authors.forename: Zhaolin
authors.initials: Z
authors.lastname: Hua
authors.forename: Todd R
authors.initials: TR
authors.lastname: Graham
mesh_terms: D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D022181:COP-Coated Vesicles / Q000378:metabolism / Q000502:physiology; D021961:Cell Membrane Structures / Q000378:metabolism; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000502:physiology; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism* / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D049294:Phospholipid Transfer Proteins; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism / Q000502:physiology
chemical_list: D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D049294:Phospholipid Transfer Proteins; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C104013:NEO1 protein, S cerevisiae