The microtubule plus-end proteins EB1 and dynactin have differential effects on microtubule polymerization
The microtubule plus-end proteins EB1 and dynactin have differential effects on microtubule polymerization
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DOI：
10.1091/mbc.e02-03-0155
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发表时间：
2003-04-01
影响因子：
3.3
通讯作者：
Holzbaur, ELF
中科院分区：
文献类型：
--
作者：
Ligon, LA;Shelly, SS;Holzbaur, ELF
几种微管结合蛋白包括EB1、dynactin、APC和CLIP-170定位于生长的微管的正端。虽然这些蛋白质可以独立地与微管结合，但它们之间相互作用的证据导致了一个正端复合物的假设。在这里，我们阐明了EB1和动力蛋白之间的相互作用，并表明EB1直接结合到p150（glue）亚基的n端。正端复合物的一个功能可能是调节微管动力学。在培养的细胞中，EB1或p150（glue）的过表达会捆绑微管，这表明它们都可能增强微管的稳定性。然而，这些束的形态却截然不同，这表明EB1和dynactin可能以不同的方式起作用。dynactin复合物的破坏增强了EB1的捆绑作用，提示dynactin可能调节EB1对微管的作用。体外实验分析了EB1和p150（glue）对微管聚合的影响，结果表明p150（glue）具有强大的微管成核效应，而EB1具有强大的微管延伸效应。整体微管动力学可能是由于正端蛋白的个体效应之间的平衡。不同细胞类型中正端蛋白的表达和调控的差异可能是先前注意到的微管动力学差异的基础。
Several microtubule-binding proteins including EB1, dynactin, APC, and CLIP-170 localize to the plus-ends of growing microtubules. Although these proteins can bind to microtubules independently, evidence for interactions among them has led to the hypothesis of a plus-end complex. Here we clarify the interaction between EB1 and dynactin and show that EB1 binds directly to the N-terminus of the p150(Glued) subunit. One function of a plus-end complex may be to regulate microtubule dynamics. Overexpression of either EB1 or p150(Glued) in cultured cells bundles microtubules, suggesting that each may enhance microtubule stability. The morphology of these bundles, however, differs dramatically, indicating that EB1 and dynactin may act in different ways. Disruption of the dynactin complex augments the bundling effect of EB1, suggesting that dynactin may regulate the effect of EB1 on microtubules. In vitro assays were performed to elucidate the effects of EB1 and p150(Glued) on microtubule polymerization, and they show that p150(Glued) has a potent microtubule nucleation effect, whereas EB1 has a potent elongation effect. Overall microtubule dynamics may result from a balance between the individual effects of plus-end proteins. Differences in the expression and regulation of plus-end proteins in different cell types may underlie previously noted differences in microtubule dynamics.