Restriction of 480/270-kD ankyrin G to axon proximal segments requires multiple ankyrin G-specific domains.
Restriction of 480/270-kD ankyrin G to axon proximal segments requires multiple ankyrin G-specific domains.
复制标题
480/270-kD Ankyrin G对轴突近端段的限制需要多个Ankyrin G特异性域。
DOI：
10.1083/jcb.142.6.1571
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发表时间：
1998-09-21
影响因子：
7.8
通讯作者：
Bennett, V
中科院分区：
文献类型：
--
作者：
Zhang, X;Bennett, V
AnkyrinG（−/−）神经元不能将电压敏感的钠通道和神经束蛋白集中在轴突近段，这表明AnkyrinG是一个结构通路的关键组成部分，参与轴突近段和可能的Ranvier节点的特殊膜结构域的组装（Zhou， D.， S. Lambert， D.L. Malen， S. Carpenter， L. Boland, and V. Bennett，手稿提交发表）。本文通过评估转染培养背根神经节神经元的gfp标记ankyrinG构建物的定位，以及测量非神经元细胞中神经束蛋白- gfp标记的ankyrinG复合物光漂白后的荧光恢复，探讨了270-kD ankyrinG限制在轴突近端片段的机制。综上所述，在背根神经节神经元中，除了保守的膜结合结构域外，多个锚定特异性结构域也参与了锚定环对轴突质膜的限制。锚定特异性谱结合结构域和尾结构域能够直接结合神经元细胞体和轴突近端段的质膜上的位点，可能尚未确定对接位点。富含丝氨酸的结构域仅存在于480- kd和270-kD的ankyrinG多肽中，有助于将ankyrinG限制在轴突近端区段，并限制锚定-神经束蛋白复合物的侧向扩散。ankyrinG的膜结合、谱结合和尾结构域也有助于限制锚定-神经束蛋白复合物的横向移动。因此，AnkyrinG的功能是作为一个集成机制，涉及多个领域之间的合作，迄今为止被视为模块化单元。这种复杂的行为解释了ankyrinB和ankyrinG在神经元中对不同位置进行排序的能力，以及这些锚蛋白在小鼠锚蛋白基因敲除中不能相互补偿的事实。
AnkyrinG (−/−) neurons fail to concentrate voltage-sensitive sodium channels and neurofascin at their axon proximal segments, suggesting that ankyrinG is a key component of a structural pathway involved in assembly of specialized membrane domains at axon proximal segments and possibly nodes of Ranvier (Zhou, D., S. Lambert, D.L. Malen, S. Carpenter, L. Boland, and V. Bennett, manuscript submitted for publication). This paper addresses the mechanism for restriction of 270-kD ankyrinG to axon proximal segments by evaluation of localization of GFP-tagged ankyrinG constructs transfected into cultured dorsal root ganglion neurons, as well as measurements of fluorescence recovery after photobleaching of neurofascin– GFP-tagged ankyrinG complexes in nonneuronal cells. A conclusion is that multiple ankyrinG-specific domains, in addition to the conserved membrane-binding domain, contribute to restriction of ankyrinG to the axonal plasma membrane in dorsal root ganglion neurons. The ankyrinG-specific spectrin-binding and tail domains are capable of binding directly to sites on the plasma membrane of neuronal cell bodies and axon proximal segments, and presumably have yet to be identified docking sites. The serine-rich domain, which is present only in 480- and 270-kD ankyrinG polypeptides, contributes to restriction of ankyrinG to axon proximal segments as well as limiting lateral diffusion of ankyrinG–neurofascin complexes. The membrane-binding, spectrin-binding, and tail domains of ankyrinG also contribute to limiting the lateral mobility of ankyrinG–neurofascin complexes. AnkyrinG thus functions as an integrated mechanism involving cooperation among multiple domains heretofore regarded as modular units. This complex behavior explains ability of ankyrinB and ankyrinG to sort to distinct sites in neurons and the fact that these ankyrins do not compensate for each other in ankyrin gene knockouts in mice.