Specific requirements for the ER to Golgi transport of GPI-anchored proteins in yeast.
GPI-anchored proteins are attached to the membrane via a glycosylphosphatidylinositol-(GPI) anchor whose carbohydrate core is conserved in all eukaryotes. Apart from membrane attachment, the precise role of the GPI-anchor is not known, but it has been proposed to play a role in protein sorting. We have investigated the transport of the yeast GPI-anchored protein Gas1p. We identified two mutant strains involved in very different cellular processes that are blocked selectively in the transport of GPI-anchored proteins before arrival to the Golgi. The end8-1/lcb1-100 mutant is defective in ceramide synthesis. In vitro data suggest a requirement for ceramides after the exit from the ER. We therefore propose that ceramides might function in the fusion of a GPI-containing vesicle with the Golgi, but we cannot exclude a role in the ER. The second mutant that blocks the transport of GPI-anchored proteins to the Golgi is ret1-1, a mutant in the alpha-subunit of coatomer. In both mutants, GPI-anchor attachment is normal and in ret1-1 cells, the GPI-anchors are remodeled with ceramide to the same extent as in wild-type cells.
Sütterlin
C
C
Biozentrum of the University of Basel, Switzerland.
Doering
T L
TL
Schimmöller
F
F
Schröder
S
S
Riezman
H
H
D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins
C066709:GAS1 protein, S cerevisiae; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D029701:Saccharomyces cerevisiae Proteins