Transport, docking and exocytosis of single secretory granules in live chromaffin cells
Transport, docking and exocytosis of single secretory granules in live chromaffin cells
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DOI：
10.1038/41329
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发表时间：
1997-07-31
期刊：
影响因子：
64.8
通讯作者：
Almers, W
中科院分区：
文献类型：
--
作者：
Steyer, JA;Horstmann, H;Almers, W
神经元维持有限的突触小泡池，这些突触小泡停靠在活跃区域并等待胞吐作用(1-4)。相比之下，释放大而致密核心的分泌颗粒的内分泌细胞没有活性区，并且对于对接池的大小（5）甚至是否存在（6）存在分歧。目前尚不清楚神经元或内分泌细胞的胞吐位点分泌囊泡如何以及多快被替换。通过使用电子显微镜，我们现在已经能够识别嗜铬细胞中的一组停靠颗粒，这些颗粒在细胞分泌时选择性地耗尽。通过倏逝波荧光显微镜（7），我们观察到单个颗粒进行胞吐作用并留下裸露的质膜斑块。新鲜颗粒以 114 nm s(-1) 的最高速度到达质膜，平均需要 6 分钟才能到达。到达后，它们的运动能力减弱了 4-food，这可能是由于对接的结果。一些颗粒分离并返回到细胞质中。我们得出的结论是，大量的对接颗粒池缓慢翻转，颗粒主动移动到其对接位点，对接是可逆的，并且电生理学测量的“快速释放池”代表了对接颗粒的一小部分。
Neurons maintain a limited pool of synaptic vesicles which are docked at active zones and are awaiting exocytosis(1-4). By contrast, endocrine cells releasing large, dense-core secretory granules have no active zones, and there is disagreement about the size(5) and even the existence(6) of the docked pool. It is not known how, and how rapidly, secretory vesicles are replaced at exocytic sites in either neurons or endocrine cells. By using electron microscopy, we have now been able to identify a pool of docked granules in chromaffin cells that is selectively depleted when cells secrete. With evanescent-wave fluorescence microscopy(7), we observed single granules undergoing exocytosis and leaving behind patches of bare plasmalemma. Fresh granules travelled to the plasmalemma at a top speed of 114 nm s(-1), taking an average of 6 min to arrive. On arrival, their motility diminished 4-food, probably as a result of docking. Some granules detached and returned to the cytosol. We conclude that a large pool of docked granules turns over slowly, that granules move actively to their docking sites, that docking is reversible, and that the 'rapidly releasable pool' measured electrophysiologically represents a small subset of docked granules.