title: Dynamics of the COPII coat with GTP and stable analogues.
abstract: We have developed an assay to monitor the assembly of the COPII coat onto liposomes in real time. We show that with Sar1pGTP bound to liposomes, a single round of assembly and disassembly of the COPII coat lasts a few seconds. The two large COPII complexes Sec23/24p and Sec13/31p bind almost instantaneously (in less than 1 s) to Sar1pGTP-doped liposomes. This binding is followed by a fast (less than 10 s) disassembly due to a 10-fold acceleration of the GTPase-activating protein activity of Sec23/24p by the Sec13/31p complex. Experiments with the phosphate analogue BeFx suggest that Sec23/24p provides residues directly involved in GTP hydrolysis on Sar1p.
authors.affiliation: Department of Molecular and Cell Biology, Howard Hugues Medical Institute, Stanley Hall, University of California, Berkeley, California 94720, USA.
authors.forename: B
authors.initials: B
authors.lastname: Antonny
authors.forename: D
authors.initials: D
authors.lastname: Madden
authors.forename: S
authors.initials: S
authors.lastname: Hamamoto
authors.forename: L
authors.initials: L
authors.lastname: Orci
authors.forename: R
authors.initials: R
authors.lastname: Schekman
mesh_terms: D022181:COP-Coated Vesicles / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D033921:Vesicular Transport Proteins
chemical_list: D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D008081:Liposomes; C079037:SEC23 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D006160:Guanosine Triphosphate; D020559:Monomeric GTP-Binding Proteins; C077395:SAR1 protein, S cerevisiae