The absence of Emp24p, a component of ER-derived COPII-coated vesicles, causes a defect in transport of selected proteins to the Golgi.
Emp24p is a type I transmembrane protein that is involved in secretory protein transport from the endoplasmic reticulum (ER) to the Golgi complex. A yeast mutant that lacks Emp24p (emp24 delta) is viable, but periplasmic invertase and the glycosylphosphatidyl-inositol-anchored plasma membrane protein Gas1p are delivered to the Golgi apparatus with reduced kinetics, whereas transport of alpha-factor, acid phosphatase and two vacuolar proteins is unaffected. Oligomerization and protease digestion studies of invertase suggest that the selective transport phenotype observed in the emp24 delta mutant is not due to a defect in protein folding or oligomerization. Consistent with a role in ER to Golgi transport, Emp24p is a component of COPII-coated, ER-derived transport vesicles that are isolated from a reconstituted in vitro budding reaction. We propose that Emp24p is involved in the sorting and/or concentration of a subset of secretory proteins into ER-derived transport vesicles.
Schimmöller
F
F
Biozentrum, University of Basel, Switzerland.
Singer-Krüger
B
B
Schröder
S
S
Krüger
U
U
Barlowe
C
C
Riezman
H
H
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005800:Genes, Fungal; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D007700:Kinetics; D000072235:Mating Factor; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis / Q000378:metabolism; D010675:Pheromones / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013347:Subcellular Fractions / Q000378:metabolism; D033921:Vesicular Transport Proteins; D043324:beta-Fructofuranosidase
D002352:Carrier Proteins; C093262:EMP24 protein, S cerevisiae; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D010455:Peptides; D010675:Pheromones; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D000072235:Mating Factor; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase