Abstract
Synaptotagmin is a multifunctional membrane protein that may regulate exo-endocytic cycling of synaptic vesicles at the presynaptic plasmalemma. Its C2B domain has been postulated to interact with a variety of effector molecules including acidic phospholipids, phosphoinositides, SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors), calcium channels, and the clathrin adaptor complex AP-2. Here we report that a basic motif within the C2B domain is required and sufficient for binding to AP-2 via its mu2 subunit and that this interaction is dependent on multimerization of the AP-2 binding site. Moreover, we show that upon fusion to a plasma membrane reporter protein this sequence is sufficient to target the chimeric molecule for internalization. We hypothesize that basic motifs within multimeric membrane proteins may represent a novel type of clathrin/AP-2-dependent endocytosis signal.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Protein Complex 2 / genetics
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Adaptor Protein Complex 2 / metabolism*
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Amino Acid Sequence
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Animals
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Binding Sites
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Calcium-Binding Proteins / chemistry*
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Calcium-Binding Proteins / genetics
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Calcium-Binding Proteins / metabolism*
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Cell Line
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Cell Membrane / metabolism
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Chemical Phenomena
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Chemistry, Physical
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Endocytosis
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Glutathione Transferase / genetics
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Membrane Glycoproteins / chemistry*
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism*
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Molecular Sequence Data
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Mutagenesis
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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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PC12 Cells
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Protein Subunits / chemistry
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Rats
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Recombinant Fusion Proteins
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Sequence Alignment
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Signal Transduction
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Structure-Activity Relationship
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Synaptotagmins
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Transfection
Substances
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Adaptor Protein Complex 2
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Calcium-Binding Proteins
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Membrane Glycoproteins
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Nerve Tissue Proteins
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Protein Subunits
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Recombinant Fusion Proteins
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Synaptotagmins
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Glutathione Transferase