DYNAMICS OF MICROTUBULES VISUALIZED BY DARK-FIELD MICROSCOPY - TREADMILLING AND DYNAMIC INSTABILITY
DYNAMICS OF MICROTUBULES VISUALIZED BY DARK-FIELD MICROSCOPY - TREADMILLING AND DYNAMIC INSTABILITY
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DOI：
10.1002/cm.970100127
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发表时间：
1988-01-01
影响因子：
--
通讯作者：
HORIO, T
中科院分区：
文献类型：
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作者：
HOTANI, H;HORIO, T
通过暗场光学显微镜观察了在体外进行跑步运动的单个微管，并研究了跑步运动与动态不稳定性之间的关系，作为微管相关蛋白（MAPs）的功能。为了通过实时观察直接演示跑步运动，我们构建了三个块微管，其中心块用四膜内蛋白修饰。在暗场显微镜下可以很容易地将装饰过的块与未装饰过的块区分开来，因为装饰过的块看起来要厚得多。在稳态条件下，一端未修饰的块的长度增加，另一端的长度减少，而修饰的中心块的长度没有变化。这些直接观察结果表明，犊牛脑微管的跑步通量为0.9 μm/h。使用类似的显微镜技术，我们之前证明了磷纤维素PC微管存在于生长阶段或缩短阶段，并且在稳态条件下（动态不稳定性）经常交替。跑步与动态不稳定性有什么关系？含有MAPs的单个3X‐微管的图像记录显示，微管经历了踩踏，没有表现出任何动态不稳定性。这表明MAPs抑制微管的动态不稳定性。也就是说，只有在微管被MAPs稳定后，跑步才能在稳态下进行。
Individual microtubules undergoing treadmilling in vitro were visualized by darkfield light microscopy, and the relationship between treadmilling and dynamic instability was studied as a function of microtubule‐associated proteins (MAPs). In order to demonstrate treadmilling directly by real‐time observation, we constructed three‐block microtubules, the center‐block of which was decorated withTetrahymenadynein. The decorated block can easily be distinguished from undecorated blocks in the darkfield microscope because the decorated one appears much thicker. At steady‐state conditions, the length of an undecorated block at one end increased and that at another end decreased, while the decorated center‐block did not change in its length. The results from these direct observations show that calf brain 3X‐microtubules exhibit a treadmilling flux of 0.9 μm/h.Using a similar microscopy technique, we previously demonstrated that phosphocellulose PC‐microtubules existed in either the growing or the shortening phase and alternated quite frequently at steady‐state conditions (dynamic instability). How does treadmilling relate to dynamic instability? An image recording of individual 3X‐microtubules containing MAPs revealed that the microtubules undergo treadmilling and do not exhibit any dynamic instability. This evidence shows that MAPs suppress the dynamic instability of microtubules. That is, treadmilling can take place in the steady state only after microtubules have been stabilized by MAPs.