title: COPII-cargo interactions direct protein sorting into ER-derived transport vesicles.
abstract: Vesicles coated with coat protein complex II (COPII) selectively transport molecules (cargo) and vesicle fusion proteins from the endoplasmic reticulum (ER) to the Golgi complex. We have investigated the role of coat proteins in cargo selection and recruitment. We isolated integral membrane and soluble cargo proteins destined for transport from the ER in complexes formed in the presence of Sar1 and Sec23/24, a subset of the COPII components, and GTP or GMP-PNP. Vesicle fusion proteins of the vSNARE family and Emp24, a member of a putative cargo carrier family, were also found in COPII complexes. The inclusion of amino-acid permease molecules into the complex depended on the presence of Shr3, a protein required for the permease to leave the ER. Resident ER proteins Sec61, BiP (Kar2) and Shr3 were not included in the complexes, indicating that the COPII components bound specifically to vesicle cargo. COPII-cargo complexes and putative cargo adaptor-cargo complexes were also isolated from COPII vesicles. Our results indicate that cargo packaging signals and soluble cargo adaptors are recognized by a recruitment complex comprising Sar1-GTP and Sec23/24.
authors.affiliation: Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley 94720, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kuehn
authors.forename: J M
authors.initials: JM
authors.lastname: Herrmann
authors.forename: R
authors.initials: R
authors.lastname: Schekman
mesh_terms: D026905:Amino Acid Transport Systems; D001692:Biological Transport; D022181:COP-Coated Vesicles; D002352:Carrier Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins; D015388:Organelles / Q000378:metabolism; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; D011956:Receptors, Cell Surface / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins
chemical_list: D026905:Amino Acid Transport Systems; C107845:BET1 protein, S cerevisiae; D002352:Carrier Proteins; C093262:EMP24 protein, S cerevisiae; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C079037:SEC23 protein, S cerevisiae; C077883:SHR3 protein, S cerevisiae; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; C106909:Sec22 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins; C077395:SAR1 protein, S cerevisiae