Abstract
Amphiphysin, a protein that is highly concentrated in nerve terminals, has been proposed to function as a linker between the clathrin coat and dynamin in the endocytosis of synaptic vesicles. Here, using a cell-free system, we provide direct morphological evidence in support of this hypothesis. Unexpectedly, we also find that amphiphysin-1, like dynamin-1, can transform spherical liposomes into narrow tubules. Moreover, amphiphysin-1 assembles with dynamin-1 into ring-like structures around the tubules and enhances the liposome-fragmenting activity of dynamin-1 in the presence of GTP. These results show that amphiphysin binds lipid bilayers, indicate a potential function for amphiphysin in the changes in bilayer curvature that accompany vesicle budding, and imply a close functional partnership between amphiphysin and dynamin in endocytosis.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Brain / metabolism
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Cattle
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Cell-Free System
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Clathrin / chemistry
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Clathrin / metabolism*
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Clathrin / ultrastructure
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Coated Pits, Cell-Membrane / physiology
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Coated Pits, Cell-Membrane / ultrastructure
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Dimerization
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Dynamin I
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Dynamins
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Endocytosis / physiology*
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GTP Phosphohydrolases / chemistry
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GTP Phosphohydrolases / metabolism*
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GTP Phosphohydrolases / ultrastructure
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Humans
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Kinetics
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Liposomes
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Microscopy, Electron
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / metabolism*
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Nerve Tissue Proteins / ultrastructure
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Recombinant Proteins / ultrastructure
Substances
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Clathrin
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Liposomes
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Nerve Tissue Proteins
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Recombinant Proteins
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amphiphysin
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Dynamin I
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GTP Phosphohydrolases
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Dynamins