Recognition of a basic AP-2 binding motif within the C2B domain of synaptotagmin is dependent on multimerization.
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.
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Isabelle
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Institut für Chemie-Biochemie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany.
Thiel
Stefanie
S
Höning
Stefan
S
Haucke
Volker
V
D033962:Adaptor Protein Complex 2 / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004705:Endocytosis; D005982:Glutathione Transferase / Q000235:genetics; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016716:PC12 Cells; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D050857:Synaptotagmins; D014162:Transfection
D033962:Adaptor Protein Complex 2; D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D050857:Synaptotagmins; D005982:Glutathione Transferase