title: ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization.
abstract: The role of ArfGAP1 in COPI vesicle biogenesis has been controversial. In work using isolated Golgi membranes, ArfGAP1 was found to promote COPI vesicle formation. In contrast, in studies using large unilamellar vesicles (LUVs) as model membranes, ArfGAP1 functioned as an uncoating factor inhibiting COPI vesicle formation. We set out to discriminate between these models. First, we reexamined the effect of ArfGAP1 on LUVs. We found that ArfGAP1 increased the efficiency of coatomer-induced deformation of LUVs. Second, ArfGAP1 and peptides from cargo facilitated self-assembly of coatomer into spherical structures in the absence of membranes, reminiscent of clathrin self-assembly. Third, in vivo, ArfGAP1 overexpression induced the accumulation of vesicles and allowed normal trafficking of a COPI cargo. Taken together, these data support the model in which ArfGAP1 promotes COPI vesicle formation and membrane traffic and identify a function for ArfGAP1 in the assembly of coatomer into COPI.
authors.affiliation: Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shiba
authors.affiliation: Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA.
authors.forename: Ruibai
authors.initials: R
authors.lastname: Luo
authors.affiliation: National Institute of Diabetes and Digestive and Kidney Disease; National Institutes of Health; Bethesda, MD USA.
authors.forename: Jenny E
authors.initials: JE
authors.lastname: Hinshaw
authors.affiliation: Department of Cell Biology; The University of Alabama at Birmingham; Birmingham, AL USA.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szul
authors.affiliation: Laboratory of Cell Biology; National Cancer Institute; Bethesda, MD USA.
authors.forename: Ryo
authors.initials: R
authors.lastname: Hayashi
authors.affiliation: Department of Cell Biology; The University of Alabama at Birmingham; Birmingham, AL USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sztul
authors.affiliation: Electron Microscopy Laboratory, ATP, SAIC-Frederick, Center for Cancer Research, National Cancer Institute; Frederick, MD USA.
authors.forename: Kunio
authors.initials: K
authors.lastname: Nagashima
authors.affiliation: Electron Microscopy Laboratory, ATP, SAIC-Frederick, Center for Cancer Research, National Cancer Institute; Frederick, MD USA.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Baxa
authors.affiliation: Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Randazzo