title: Several ADP-ribosylation factor (Arf) isoforms support COPI vesicle formation.
abstract: Newly synthesized proteins and lipids are transported in vesicular carriers along the secretory pathway. Arfs (ADP-ribosylation factors), a family of highly conserved GTPases within the Ras superfamily, control recruitment of molecular coats to membranes, the initial step of coated vesicle biogenesis. Arf1 and coatomer constitute the minimal cytosolic machinery leading to COPI vesicle formation from Golgi membranes. Although some functional redundancies have been suggested, other Arf isoforms have been poorly analyzed in this context. In this study, we found that Arf1, Arf4, and Arf5, but not Arf3 and Arf6, associate with COPI vesicles generated in vitro from Golgi membranes and purified cytosol. Using recombinant myristoylated proteins, we show that Arf1, Arf4, and Arf5 each support COPI vesicle formation individually. Unexpectedly, we found that Arf3 could also mediate vesicle biogenesis. However, Arf3 was excluded from the vesicle fraction in the presence of the other isoforms, highlighting a functional competition between the different Arf members.
authors.affiliation: Heidelberg University Biochemistry Center (BZH), University of Heidelberg, INF 364, 69120 Heidelberg, Germany. Electronic address: vincent.popoff@bzh.uni-heidelberg.de.
authors.forename: Vincent
authors.initials: V
authors.lastname: Popoff
authors.affiliation: Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.
authors.forename: Julian D
authors.initials: JD
authors.lastname: Langer
authors.affiliation: Heidelberg University Biochemistry Center (BZH), University of Heidelberg, INF 364, 69120 Heidelberg, Germany.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Reckmann
authors.affiliation: Department of Neurobiology IZN, University of Heidelberg, INF 364, 69120 Heidelberg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hellwig
authors.affiliation: Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kahn
authors.affiliation: Heidelberg University Biochemistry Center (BZH), University of Heidelberg, INF 364, 69120 Heidelberg, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Brügger
authors.affiliation: Heidelberg University Biochemistry Center (BZH), University of Heidelberg, INF 364, 69120 Heidelberg, Germany.
authors.forename: Felix T
authors.initials: FT
authors.lastname: Wieland
mesh_terms: D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D022181:COP-Coated Vesicles / Q000201:enzymology* / Q000235:genetics; D006056:Golgi Apparatus / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D007425:Intracellular Membranes / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D054878:Lipoylation / Q000502:physiology; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D011994:Recombinant Proteins; D020727:ADP-Ribosylation Factors