Sankaranarayanan S, Ryan T A
Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10021, USA.
Nat Cell Biol. 2000 Apr;2(4):197-204. doi: 10.1038/35008615.
Following the fusion of synaptic vesicles with the presynaptic plasma membrane of nerve terminals by the process of exocytosis, synaptic-vesicle components are recycled to replenish the vesicle pool. Here we use a pH-sensitive green fluorescent protein to measure the residence time of VAMP, a vesicle-associated SNARE protein important for membrane fusion, on the surfaces of synaptic terminals of hippocampal neurons following exocytosis. The time course of VAMP retrieval depends linearly on the amount of VAMP that is added to the plasma membrane, with retrieval occurring between about 4 seconds and 90 seconds after exocytosis, and newly internalized vesicles are rapidly acidified. These data are well described by a model in which endocytosis appears to be saturable, but proceeds with an initial maximum velocity of about one vesicle per second. We also find that, following exocytosis, a portion of the newly inserted VAMP appears on the surface of the axon.
在通过胞吐作用使突触小泡与神经末梢的突触前质膜融合后，突触小泡成分被循环利用以补充小泡池。在此，我们使用一种pH敏感的绿色荧光蛋白来测量VAMP（一种对膜融合很重要的与小泡相关的SNARE蛋白）在海马神经元突触末梢胞吐后表面的驻留时间。VAMP回收的时间进程线性依赖于添加到质膜上的VAMP量，回收发生在胞吐后约4秒至90秒之间，并且新内化的小泡会迅速酸化。这些数据可以很好地用一个模型来描述，在该模型中内吞作用似乎是可饱和的，但最初以每秒约一个小泡的最大速度进行。我们还发现，在胞吐后，一部分新插入的VAMP出现在轴突表面。
