Hunt J M, Bommert K, Charlton M P, Kistner A, Habermann E, Augustine G J, Betz H
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710.
Neuron. 1994 Jun;12(6):1269-79. doi: 10.1016/0896-6273(94)90443-x.
We have used the squid giant synapse to determine the role of synaptobrevin, integral membrane proteins of small synaptic vesicles, in neurotransmitter release. The sequence of squid synaptobrevin, deduced by cDNA cloning, is 65%-68% identical to mammalian isoforms and includes the conserved cleavage site for tetanus and botulinum B toxins. Injection of either toxin into squid nerve terminals caused a slow, irreversible inhibition of release without affecting the Ca2+ signal which triggers release. Microinjection of a recombinant protein corresponding to the cytoplasmic domain of synaptobrevin produced a more rapid and reversible inhibition of release, whereas two smaller peptide fragments were without effect. Electron microscopy of tetanus-injected terminals revealed an increased number of both docked and undocked synaptic vesicles. These data indicate that synaptobrevin participates in neurotransmitter release at a step between vesicle docking and fusion.
我们利用枪乌贼巨大突触来确定小突触囊泡的整合膜蛋白突触囊泡蛋白在神经递质释放中的作用。通过cDNA克隆推导的枪乌贼突触囊泡蛋白序列与哺乳动物异构体的序列有65%-68%的同源性，并且包含破伤风毒素和肉毒杆菌B毒素的保守切割位点。将这两种毒素中的任何一种注射到枪乌贼神经末梢都会导致释放的缓慢、不可逆抑制，而不影响触发释放的Ca2+信号。显微注射与突触囊泡蛋白胞质结构域对应的重组蛋白会产生更快且可逆的释放抑制，而两个较小的肽片段则没有作用。对注射破伤风毒素的神经末梢进行电子显微镜观察发现，停靠和未停靠的突触囊泡数量均增加。这些数据表明，突触囊泡蛋白在囊泡停靠和融合之间的步骤参与神经递质释放。
