Structural changes after transmitter release at the frog neuromuscular junction.
Structural changes after transmitter release at the frog neuromuscular junction.
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DOI：
10.1083/jcb.88.3.564
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发表时间：
1981-03
影响因子：
7.8
通讯作者：
Reese, T S
中科院分区：
文献类型：
--
作者：
Heuser, J E;Reese, T S
突触囊泡胞吐过程中发生的结构变化的顺序进行了研究，通过速冻肌肉在不同的时间间隔刺激后，在4-氨基吡啶的存在下，以增加每个刺激释放的递质量子的数量。单次刺激后3-4 ms内，肌内神经活动区开始出现囊泡开口。这些开口的浓度在5-6 ms达到峰值，然后在50-100 ms后下降到零。在后期，囊泡开口往往更大。在囊泡开口消失后，留在活性区的是大的膜内颗粒簇。这些簇中的较大颗粒与未放电囊泡中的膜内颗粒大小相同，并且略大于形成描绘活性区的行的颗粒。由于以前的示踪剂工作表明，新的囊泡不夹断从质膜在这些早期的时间，我们得出的结论是，颗粒团起源于膜的放电囊泡后，崩溃到质膜胞吐。囊泡塌陷的速率似乎是可变的，因为在刺激后的大多数时间内同时发生不同的阶段;这种差异表明每个胞吐囊泡的塌陷被先前的附近塌陷减缓。突触囊泡膜塌陷后的最终命运似乎是与质膜合并，因为在刺激后的第一秒内，颗粒簇逐渐分散到周围区域。正如之前的报告所述，逆转这种胞吐序列的膜回收和再循环的启动速度较慢。
The sequence of structural changes that occur during synaptic vesicle exocytosis was studied by quick-freezing muscles at different intervals after stimulating their nerves, in the presence of 4-aminopyridine to increase the number of transmitter quanta released by each stimulus. Vesicle openings began to appear at the active zones of the intramuscular nerves within 3-4 ms after a single stimulus. The concentration of these openings peaked at 5-6 ms, and then declined to zero 50-100 ms late. At the later times, vesicle openings tended to be larger. Left behind at the active zones, after the vesicle openings disappeared, were clusters of large intramembrane particles. The larger particles in these clusters were the same size as intramembrane particles in undischarged vesicles, and were slightly larger than the particles which form the rows delineating active zones. Because previous tracer work had shown that new vesicles do not pinch off from the plasma membrane at these early times, we concluded that the particle clusters originate from membranes of discharged vesicles which collapse into the plasmalemma after exocytosis. The rate of vesicle collapse appeared to be variable because different stages occurred simultaneously at most times after stimulation; this asynchrony was taken to indicate that the collapse of each exocytotic vesicle is slowed by previous nearby collapses. The ultimate fate of synaptic vesicle membrane after collapse appeared to be coalescence with the plasma membrane, as the clusters of particles gradually dispersed into surrounding areas during the first second after a stimulus. The membrane retrieval and recycling that reverse this exocytotic sequence have a slower onset, as has been described in previous reports.