Role for Gcs1p in regulation of Arl1p at trans-Golgi compartments.
ADP-ribosylation factor (ARF) and ARF-like (ARL) proteins are members of the ARF family, which are critical components of several different vesicular trafficking pathways. ARFs have little or no detectable GTPase activity without the assistance of a GTPase-activating protein (GAP). Here, we demonstrate that yeast Gcs1p exhibits GAP activity toward Arl1p and Arf1p in vitro, and Arl1p can interact with Gcs1p in a GTP-dependent manner. Arl1p was observed both on trans-Golgi and in cytosol and was recruited from cytosol to membranes in a GTP-dependent manner. In gcs1 mutant cells, the fraction of Arl1p in cytosol relative to trans-Golgi was less than it was in wild-type cells. Increasing Gcs1p levels returned the distribution toward that of wild-type cells. Both Arl1p and Gcs1p influenced the distribution of Imh1p, an Arl1p effector. Our data are consistent with the conclusion that Arl1p moves in a dynamic equilibrium between trans-Golgi and cytosol, and the release of Arl1p from membranes in cells requires the hydrolysis of bound GTP, which is accelerated by Gcs1p.
Institute of Molecular Medicine, College of Medicine, and Department of Medical Research, National Taiwan University Hospital, National Taiwan University, Taipei 100, Taiwan.
Ya-Wen
YW
Liu
Chun-Fang
CF
Huang
Kai-Bin
KB
Huang
Fang-Jen S
FJ
Lee
D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000502:physiology*; D017930:Genes, Reporter; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism* / Q000502:physiology*; D013194:Staining and Labeling; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism*
D004268:DNA-Binding Proteins; C089147:GCS1 protein, S cerevisiae; D020690:GTPase-Activating Proteins; D009711:Nucleotides; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C487039:ARL1 protein, S cerevisiae; D020823:ADP-Ribosylation Factor 1; D020559:Monomeric GTP-Binding Proteins