人类的大脑就像是一个有机超级计算机，它能有条不紊井然有序迅速地解决从呼吸到猜谜等所有难题。近日科学家首次描述了神经细胞是如何在瞬间管理其信号的传输过程，该研究成果发表在最近出版的《科学》（Science）杂志上。
神经系统细胞使用多巴胺、血清素及去甲肾上腺素等小分子神经递质进行沟通。多巴胺与诸如记忆等认知功能相关，而血清素负责情绪控制，去甲肾上腺素则与注意力和觉醒有关。脑细胞通过神经突触传递化学递质构成复杂的信息网络系统。电信号可以使突触小泡与膜融合，并将化学递质释放，这一过程以毫秒的速度发生。
哥本哈根哥廷根大学和阿姆斯特丹大学的研究人员一直在研究参与膜融合的核心蛋白复合物（SNARE复合体），为大脑神经的迅捷传递速度寻求解释。他们发现，突触小泡含有不少于3份连接桥或“SNARE复合体”。囊泡只和一个SNARE复合体较长时间地与细胞膜融合，慢慢地分泌神经递质。SNARE复合体的前体在囊泡到达目标膜之前出现。至少有三个SNARE复合体串联时，同步融合启动。如果小泡只有一个SNARE复合体，就会长时间与目标膜融合。
哥本哈根大学神经科学和药理学系的索伦森表示，下一步他们将研究影响和调节SNARE复合体在小泡中数量的各种因素，以确定是否与神经细胞传递信息的快慢有关。且大脑一旦发生病变，是否会改变这种调节规律。
推荐英文摘要：
Science DOI: 10.1126/science.1193134
Fast Vesicle Fusion in Living Cells Requires at Least Three SNARE Complexes
Ralf Mohrmann,1,2,* Heidi de Wit,3 Matthijs Verhage,3 Erwin Neher,1 Jakob B. S?rensen1,4,5,*
Exocytosis requires formation of SNARE complexes between vesicle- and target-membranes. Recent assessments in reduced model systems have produced divergent estimates of the number of SNARE complexes needed for fusion. Here, we used a titration approach to answer this question in intact, cultured chromaffin cells. Simultaneous expression of wild-type SNAP-25 and a mutant unable to support exocytosis progressively altered fusion kinetics and fusion pore opening, indicating that both proteins assemble into heteromeric fusion complexes. Expressing different wild-type:mutant ratios revealed a third power relationship for fast (synchronous) fusion and a near-linear relationship for overall release. Thus, fast fusion typically observed in synapses and neurosecretory cells requires at least three functional SNARE complexes, while slower release might occur with fewer. Heterogeneity in SNARE-complex number may explain heterogeneity in vesicular release probability.
1 Department of Membrane Biophysics, Max-Planck Institute for Biophysical Chemistry, G?ttingen, Germany.
2 Department of Physiology, University of Saarland, Homburg, Germany.
3 Center for Neurogenomics and Cognitive Research, Department of Functional Genomics, Vrije Universiteit Amsterdam and VU Medical Center, Amsterdam, Netherlands.
4 Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
5 Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark.
