Abstract
COPI-coated vesicle budding from lipid bilayers whose composition resembles mammalian Golgi membranes requires coatomer, ARF, GTP, and cytoplasmic tails of putative cargo receptors (p24 family proteins) or membrane cargo proteins (containing the KKXX retrieval signal) emanating from the bilayer surface. Liposome-derived COPI-coated vesicles are similar to their native counterparts with respect to diameter, buoyant density, morphology, and the requirement for an elevated temperature for budding. These results suggest that a bivalent interaction of coatomer with membrane-bound ARF[GTP] and with the cytoplasmic tails of cargo or putative cargo receptors is the molecular basis of COPI coat assembly and provide a simple mechanism to couple uptake of cargo to transport vesicle formation.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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ADP-Ribosylation Factors
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Amino Acid Sequence
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Animals
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Biological Transport / physiology
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Carrier Proteins / metabolism
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Cell Compartmentation / physiology
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Coatomer Protein
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Cytoplasm / chemistry
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Cytoplasm / metabolism
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Cytoplasmic Granules / chemistry
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Cytoplasmic Granules / metabolism*
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GTP-Binding Proteins / metabolism
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Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
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Guanosine Triphosphate / metabolism
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Humans
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Lipid Bilayers / chemistry
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Lipid Bilayers / metabolism*
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Liposomes / chemistry
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Liposomes / metabolism
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Membrane Proteins / analysis
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Molecular Sequence Data
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Peptide Fragments / analysis
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Peptide Fragments / metabolism
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Protein Binding / drug effects
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Protein Binding / physiology
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Rabbits
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Temperature
Substances
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Carrier Proteins
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Coatomer Protein
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Lipid Bilayers
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Liposomes
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Membrane Proteins
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Peptide Fragments
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Guanosine 5'-O-(3-Thiotriphosphate)
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Guanosine Triphosphate
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GTP-Binding Proteins
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ADP-Ribosylation Factors