The ARF exchange factors Gea1p and Gea2p regulate Golgi structure and function in yeast.
The Sec7 domain guanine nucleotide exchange factors (GEFs) for the GTPase ARF are highly conserved regulators of membrane dynamics. Their precise molecular roles in different trafficking steps within the cell have not been elucidated. We present a functional analysis of two members of this family, Gea1p and Gea2p, in the yeast Saccharomyces cerevisiae. Gea1p and Gea2p can functionally replace each other, but at least one is necessary for viability. Temperature sensitive gea mutants were generated and found to have defects in ER-Golgi and intra-Golgi transport. Similar to mutants in COPI subunits in yeast, gea mutants had a cargo-selective secretion defect, in that some proteins continued to be secreted whereas others were blocked in the ER or early Golgi. Like yeast arf mutants, the rate of transport of those proteins that continued to be secreted was slowed. In addition, the structure of Golgi elements was severely perturbed in gea mutants. We conclude that Gea1p and Gea2p play an important role in the structure and functioning of the Golgi apparatus in yeast.
Peyroche
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Service de Biochimie et Génétique Moléculaire, Bat. 142, Département de Biologie Cellulaire et Moléculaire, CEA/Saclay, 91191 Gif-sur-Yvette, France.
Courbeyrette
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Rambourg
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Jackson
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D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D020126:Brefeldin A / Q000494:pharmacology; D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006056:Golgi Apparatus / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D008364:Mannosyltransferases; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; C102475:GEA1 protein, S cerevisiae; C121632:GEA2 protein, S cerevisiae; D020662:Guanine Nucleotide Exchange Factors; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C075636:OCH1 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D020126:Brefeldin A; C090211:ANP1 protein, S cerevisiae; C086604:MNN1 protein, S cerevisiae; D008364:Mannosyltransferases; D002268:Carboxypeptidases; D043402:Cathepsin A; D020727:ADP-Ribosylation Factors