Requirement for neo1p in retrograde transport from the Golgi complex to the endoplasmic reticulum.

Hua Z, Graham TR
Mol Biol Cell. 2003 14 (12): 4971-83

PMID: 12960419 · PMCID: PMC284799 · DOI:10.1091/mbc.e03-07-0463

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.

MeSH Terms (18)

Adenosine Triphosphatases Amino Acid Sequence Cell Membrane Structures Cloning, Molecular COP-Coated Vesicles Endoplasmic Reticulum Glycosylation Golgi Apparatus Membrane Proteins Membrane Transport Proteins Microscopy, Electron Models, Molecular Molecular Sequence Data Phospholipid Transfer Proteins Protein Transport Saccharomyces cerevisiae Saccharomyces cerevisiae Proteins Vacuoles

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