GDI1 encodes a GDP dissociation inhibitor that plays an essential role in the yeast secretory pathway.
GTP binding proteins of the Sec4/Ypt/rab family regulate distinct vesicular traffic events in eukaryotic cells. We have cloned GDI1, an essential homolog of bovine rab GDI (GDP dissociation inhibitor) from the yeast Saccharomyces cerevisiae. Analogous to the bovine protein, purified Gdi1p slows the dissociation of GDP from Sec4p and releases the GDP-bound form from yeast membranes. Depletion of Gdi1p in vivo leads to loss of the soluble pool of Sec4p and inhibition of protein transport at multiple stages of the secretory pathway. Complementation analysis indicates that GDI1 is allelic to sec19-1. These results establish that Gdi1p plays an essential function in membrane traffic and are consistent with a role for Gdi1p in the recycling of proteins of the Sec4/Ypt/rab family from their target membranes back to their vesicular pools.
Garrett
M D
MD
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
Zahner
J E
JE
Cheney
C M
CM
Novick
P J
PJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000502:physiology / Q000648:ultrastructure; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal / Q000235:genetics*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006056:Golgi Apparatus / Q000502:physiology / Q000648:ultrastructure; D020730:Guanine Nucleotide Dissociation Inhibitors; D007546:Isoquinolines / Q000378:metabolism; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D043324:beta-Fructofuranosidase; D020691:rab GTP-Binding Proteins; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
D005656:Fungal Proteins; C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D007546:Isoquinolines; D029701:Saccharomyces cerevisiae Proteins; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; C017475:lucifer yellow; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; D019204:GTP-Binding Proteins; C064320:SEC4 protein, S cerevisiae; D020691:rab GTP-Binding Proteins