Yeast ARV1 is required for efficient delivery of an early GPI intermediate to the first mannosyltransferase during GPI assembly and controls lipid flow from the endoplasmic reticulum.
Glycosylphosphatidylinositol (GPI), covalently attached to many eukaryotic proteins, not only acts as a membrane anchor but is also thought to be a sorting signal for GPI-anchored proteins that are associated with sphingolipid and sterol-enriched domains. GPI anchors contain a core structure conserved among all species. The core structure is synthesized in two topologically distinct stages on the leaflets of the endoplasmic reticulum (ER). Early GPI intermediates are assembled on the cytoplasmic side of the ER and then are flipped into the ER lumen where a complete GPI precursor is synthesized and transferred to protein. The flipping process is predicted to be mediated by a protein referred as flippase; however, its existence has not been proven. Here we show that yeast Arv1p is an important protein required for the delivery of an early GPI intermediate, GlcN-acylPI, to the first mannosyltransferase of GPI synthesis in the ER lumen. We also provide evidence that ARV1 deletion and mutations in other proteins involved in GPI anchor synthesis affect inositol phosphorylceramide synthesis as well as the intracellular distribution and amounts of sterols, suggesting a role of GPI anchor synthesis in lipid flow from the ER.
Kajiwara
Kentaro
K
Department of Bioresource Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
Watanabe
Reika
R
Pichler
Harald
H
Ihara
Kensuke
K
Murakami
Suguru
S
Riezman
Howard
H
Funato
Kouichi
K
D000117:Acetylglucosamine / Q000096:biosynthesis; D001692:Biological Transport / Q000187:drug effects; D002518:Ceramides / Q000378:metabolism; D047630:Depsipeptides / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005800:Genes, Fungal; D006028:Glycosphingolipids / Q000096:biosynthesis; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D008358:Mannose / Q000096:biosynthesis; D008364:Mannosyltransferases / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism
C467736:ARV1 protein, S cerevisiae; D002518:Ceramides; D047630:Depsipeptides; D006028:Glycosphingolipids; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; C477937:inositolphosphorylceramide; C071398:aureobasidin A; D008364:Mannosyltransferases; D008358:Mannose; D000117:Acetylglucosamine