title: Involvement of Ca2+ channel synprint site in synaptic vesicle endocytosis.
abstract: The synaptic protein interaction (synprint) site of the voltage-gated Ca(2+) channel (VGCC) alpha1 subunit can interact with proteins involved in exocytosis, and it is therefore thought to be essential for exocytosis of synaptic vesicles. Here we report that the synprint site can also directly bind the mu subunit of AP-2, an adaptor protein for clathrin-mediated endocytosis, in competition with the synaptotagmin 1 (Syt 1) C2B domain. In brain lysates, the AP-2-synprint interaction occurred over a wide range of Ca(2+) concentrations but was inhibited at high Ca(2+) concentrations, in which Syt 1 interacted with synprint site. At the calyx of Held synapse in rat brainstem slices, direct presynaptic loading of the synprint fragment peptide blocked endocytic, but not exocytic, membrane capacitance changes. We propose that the VGCC synprint site is involved in synaptic vesicle endocytosis, rather than exocytosis, in the nerve terminal, via Ca(2+)-dependent interactions with AP-2 and Syt.
authors.affiliation: Cellular and Molecular Synaptic Function Unit, Initial Research Project, Okinawa Institute of Science and Technology Promotion Corporation, Okinawa 904-2234, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Watanabe
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yamashita
authors.forename: Naoto
authors.initials: N
authors.lastname: Saitoh
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kiyonaka
authors.forename: Akihiro
authors.initials: A
authors.lastname: Iwamatsu
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Campbell
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Mori
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites / Q000502:physiology; D055592:Biophysical Phenomena / Q000187:drug effects / Q000235:genetics; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D015220:Calcium Channels / Q000134:cerebrospinal fluid / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000379:methods; D004705:Endocytosis / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D004676:Myelin Basic Protein / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017354:Point Mutation / Q000502:physiology; D017729:Presynaptic Terminals / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins; D013329:Structure-Activity Relationship; D013477:Superior Colliculi / Q000166:cytology; D013569:Synapses / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000502:physiology*; D050863:Synaptotagmin I / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D004268:DNA-Binding Proteins; D004676:Myelin Basic Protein; D011993:Recombinant Fusion Proteins; D050863:Synaptotagmin I; C083115:activator protein-2 binding element; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D002118:Calcium