Bommert K, Charlton M P, DeBello W M, Chin G J, Betz H, Augustine G J
Marine Biological Laboratory, Woods Hole, Massachusetts 02543.
Nature. 1993 May 13;363(6425):163-5. doi: 10.1038/363163a0.
Neurotransmitter release is triggered by Ca2+ ions binding to an unknown Ca2+ receptor within presynaptic terminals. Synaptotagmin, a Ca2(+)-binding protein of synaptic and other secretory vesicles, has been proposed to mediate vesicle-plasma membrane interactions during neurotransmitter release. Here we test this hypothesis using the giant synapse of the squid Loligo pealei, which because of its unusually large size and well established physiology is uniquely suited for dissecting presynaptic events. We find that injection of peptides from the C2 domains of synaptotagmin into squid giant presynaptic terminals rapidly and reversibly inhibits neurotransmitter release. Our data are consistent with these peptides competitively blocking release after synaptic vesicle docking and indicate that Ca2+ probably initiates neurotransmitter release by regulating the interaction of synaptotagmin with an acceptor protein.
神经递质的释放是由钙离子与突触前终末内一种未知的钙离子受体结合所触发的。突触结合蛋白是一种存在于突触小泡和其他分泌小泡中的钙离子结合蛋白，有人提出它在神经递质释放过程中介导小泡与质膜的相互作用。在此，我们利用枪乌贼（Loligo pealei）的巨大突触来检验这一假说，由于其尺寸异常大且生理学特性已充分确立，它特别适合用于剖析突触前事件。我们发现，将来自突触结合蛋白C2结构域的肽段注射到枪乌贼巨大突触前终末中，能快速且可逆地抑制神经递质的释放。我们的数据与这些肽段在突触小泡对接后竞争性阻断释放的情况相符，表明钙离子可能通过调节突触结合蛋白与一种受体蛋白的相互作用来启动神经递质的释放。
