title: The yeast ADP-ribosylation factor GAP, Gcs1p, is involved in maintenance of mitochondrial morphology.
abstract: Membrane trafficking is regulated, in part, by small GTP-binding proteins of the ADP-ribosylation factor (ARF) family. ARF function depends on the controlled binding and hydrolysis of GTP. In vitro, the GTPase activity of yeast ARF proteins can be stimulated by Gcs1p. Although Gcs1p was implicated in the regulation of retrograde transport from the Golgi to the ER and in actin cytoskeletal organization, its intracellular functions and distribution remain to be established. Following subcellular fractionation of yeast grown in rich medium, Gcs1p was localized in denser fractions than it was in cells grown in minimal medium. In yeast grown in rich or minimal medium, Gcs1p was distributed over the cytoplasm in a fine punctate pattern with more concentrated staining in the perinuclear regions. Overexpressed Gcs1p in yeast was localized partially with mitochondria and partially in perinuclear structures close to mitochondria. The Gcs1p PH-domain was required for localization in mitochondria but not for the perinuclear region. Transport of carboxypeptidase Y and invertase was not significantly altered by disruption of the gcs1 gene. This mutation did, however, reduce mitochondrial lateral distribution and branching when yeast were grown in rich medium. In yeast overexpressing Gcs1p, mitochondrial morphology was aberrant, with unbranched tubules and large spherical structures. We suggest that Gcs1p may be involved in the maintenance of mitochondrial morphology, possibly through organizing the actin cytoskeleton in Saccharomyces.
authors.affiliation: Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Chun-Fang
authors.initials: CF
authors.lastname: Huang
authors.forename: Chien-Cheng
authors.initials: CC
authors.lastname: Chen
authors.forename: Luh
authors.initials: L
authors.lastname: Tung
authors.forename: Leh-Miauh
authors.initials: LM
authors.lastname: Buu
authors.forename: Fang-Jen S
authors.initials: FJ
authors.lastname: Lee
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D008841:Actin Cytoskeleton / Q000378:metabolism*; D002451:Cell Compartmentation / Q000502:physiology; D048429:Cell Size / Q000235:genetics; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology*; D012440:Saccharomyces / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016335:Zinc Fingers / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C089147:GCS1 protein, S cerevisiae; D020690:GTPase-Activating Proteins; D029701:Saccharomyces cerevisiae Proteins; D020727:ADP-Ribosylation Factors