The GTP-binding protein Ypt1 is required for transport in vitro: the Golgi apparatus is defective in ypt1 mutants.
The YPT1 gene encodes a raslike, GTP-binding protein that is essential for growth of yeast cells. We show here that mutations in the ypt1 gene disrupt transport of carboxypeptidase Y to the vacuole in vivo and transport of pro-alpha-factor to a site of extensive glycosylation in the Golgi apparatus in vitro. Two different ypt1 mutations result in loss of function of the Golgi complex without affecting the activity of the endoplasmic reticulum or soluble components required for in vitro transport. The function of the mutant Golgi apparatus can be restored by preincubation with wild-type cytosol. The transport defect observed in vitro cannot be overcome by addition of Ca++ to the reaction mixture. We have also established genetic interactions between ypt1 and a subset of the other genes required for transport to and through the Golgi apparatus.
Bacon
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RA
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Salminen
A
A
Ruohola
H
H
Novick
P
P
Ferro-Novick
S
S
D000483:Alleles; D002118:Calcium / Q000378:metabolism; D002268:Carboxypeptidases / Q000235:genetics; D043402:Cathepsin A; D005656:Fungal Proteins / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005796:Genes; D005800:Genes, Fungal; D006031:Glycosylation; D006056:Golgi Apparatus / Q000502:physiology*; D009154:Mutation; D011498:Protein Precursors / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity; D014617:Vacuoles / Q000378:metabolism; D020691:rab GTP-Binding Proteins
D005656:Fungal Proteins; C048632:MF(ALPHA)1 protein, S cerevisiae; D011498:Protein Precursors; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; C022633:serine carboxypeptidase; D019204:GTP-Binding Proteins; C060755:YPT1 protein, S cerevisiae; D020691:rab GTP-Binding Proteins; D002118:Calcium