Yeast GGA proteins interact with GTP-bound Arf and facilitate transport through the Golgi.
ARF proteins regulate the formation of transport vesicles at many steps of the secretory and endocytic pathways. A recently identified family of ARF effectors, named GGAs, appears to regulate membrane traffic exiting the trans-Golgi network in mammalian cells (Boman et al., 2000). We have identified two GGA homologues in the yeast S. cerevisiae. These previously uncharacterized open reading frames, YDR358w and YHR108w, have been named GGA1 and GGA2, respectively. Using the two-hybrid assay and GST-affinity chromatography, we show that Gga1p and Gga2p interact with Arf1p and Arf2p in a GTP-dependent manner, suggesting that both are functional homologues of the human GGA proteins. The Arf-binding domain resides in the amino-terminal half of Gga1p (amino acids 170-330), and the carboxy-terminal 100 amino acids resemble the gamma-adaptin 'ear domain'. Gene deletion experiments indicate that GGA1 and GGA2 are not essential genes, as single and double knockouts are viable at both 30 degrees C and 37 degrees C. However, cells lacking GGA1 and GGA2 exhibit defects in invertase processing and CPY sorting, but not endocytosis. We conclude that yeast Gga proteins are effectors of Arf in yeast that facilitate traffic through the late Golgi.
Zhdankina
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O
Department of Biochemistry and Molecular Biology, University of Minnesota, School of Medicine, Duluth, MN 55812, USA.
Strand
N L
NL
Redmond
J M
JM
Boman
A L
AL
D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism*; D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000908:Antibodies, Fungal / Q000276:immunology; D000918:Antibody Specificity; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D002846:Chromatography, Affinity; D017124:Conserved Sequence; D020043:Genes, Essential; D005800:Genes, Fungal; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D020798:Two-Hybrid System Techniques; D021601:trans-Golgi Network / Q000378:metabolism*
D033942:Adaptor Proteins, Vesicular Transport; D000908:Antibodies, Fungal; D002352:Carrier Proteins; C407306:GGA adaptor proteins; D029701:Saccharomyces cerevisiae Proteins; D006160:Guanosine Triphosphate; C116686:ARF2 protein, S cerevisiae; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C116688:ARF4 protein, human