Richards David A, Bai Jihong, Chapman Edwin R
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706, USA.
J Cell Biol. 2005 Mar 14;168(6):929-39. doi: 10.1083/jcb.200407148.
We have examined the kinetics by which FM1-43 escapes from individual synaptic vesicles during exocytosis at hippocampal boutons. Two populations of exocytic events were observed; small amplitude events that lose dye slowly, which made up more than half of all events, and faster, larger amplitude events with a fluorescence intensity equivalent to single stained synaptic vesicles. These populations of destaining events are distinct in both brightness and kinetics, suggesting that they result from two distinct modes of exocytosis. Small amplitude events show tightly clustered rate constants of dye release, whereas larger events have a more scattered distribution. Kinetic analysis of the association and dissociation of FM1-43 with membranes, in combination with a simple pore permeation model, indicates that the small, slowly destaining events may be mediated by a narrow approximately 1-nm fusion pore.
我们研究了FM1-43在海马小体胞吐过程中从单个突触小泡中逸出的动力学。观察到两种胞吐事件类型；染料缓慢丢失的小幅度事件，占所有事件的一半以上，以及更快、幅度更大且荧光强度相当于单个染色突触小泡的事件。这些去染色事件类型在亮度和动力学上都不同，表明它们源于两种不同的胞吐模式。小幅度事件显示染料释放的速率常数紧密聚集，而较大事件的分布则更为分散。结合简单的孔渗透模型对FM1-43与膜的结合和解离进行动力学分析表明，小的、缓慢去染色的事件可能由一个狭窄的约1纳米融合孔介导。
