Abstract
The synaptic vesicle protein synaptotagmin was proposed to act as a major docking site for the recruitment of clathrin coats implicated in endocytosis, including the recycling of synaptic vesicles. We show here that the C2B domain of synaptotagmin binds mu2- and alpha-adaptin, two of the four subunits of the endocytic adaptor complex AP-2. mu2 represents the major interacting subunit of AP-2 within this complex. Its binding to synaptotagmin is mediated by a site in subdomain B that is distinct from the binding site for tyrosine-based sorting motifs located in subdomain A. The presence of the C2B domain of synaptotagmin at the surface of liposomes enhances the recruitment of AP-2 and clathrin. Conversely, perturbation of the interaction between synaptotagmin and AP-2 by synprint, the cytoplasmic synaptotagmin-binding domain of N-type calcium channels, inhibits transferrin internalization in living cells. We conclude that a dual interaction of synaptotagmin with the clathrin adaptor AP-2 plays a key physiological role in the nucleation of endocytic clathrin-coated pits.
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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Adaptor Protein Complex 1*
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Adaptor Protein Complex 2*
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Adaptor Protein Complex 3*
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Adaptor Protein Complex alpha Subunits
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Adaptor Protein Complex mu Subunits*
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Adaptor Proteins, Vesicular Transport
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Animals
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Binding Sites
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CHO Cells
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Calcium-Binding Proteins*
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Clathrin / chemistry
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Clathrin / metabolism*
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Coated Pits, Cell-Membrane / metabolism*
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Cricetinae
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In Vitro Techniques
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Liposomes
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Lysine / chemistry
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Membrane Glycoproteins / chemistry
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Membrane Glycoproteins / metabolism*
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Mutation
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism*
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Phosphoproteins / chemistry
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Phosphoproteins / genetics
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Phosphoproteins / metabolism*
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Protein Subunits
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Rats
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Synaptic Vesicles / metabolism
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Synaptotagmins
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Tyrosine / chemistry
Substances
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Adaptor Protein Complex 1
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Adaptor Protein Complex 2
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Adaptor Protein Complex 3
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Adaptor Protein Complex alpha Subunits
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Adaptor Protein Complex mu Subunits
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Adaptor Proteins, Vesicular Transport
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Ap3m2 protein, rat
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Calcium-Binding Proteins
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Clathrin
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Liposomes
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Membrane Glycoproteins
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Membrane Proteins
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Nerve Tissue Proteins
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Phosphoproteins
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Protein Subunits
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adaptor protein complex 1, mu 2 subunit
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adaptor protein complex 2, mu 2 subunit
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Synaptotagmins
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Tyrosine
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Lysine