Nara Institute of Science and Technology, Graduate School of Biological Sciences, Japan.
Curr Opin Plant Biol. 2013 Dec;16(6):698-703. doi: 10.1016/j.pbi.2013.09.002. Epub 2013 Sep 25.
The construction of dynamic polar microtubules from 13 protofilaments consisting of α-tubulin and β-tubulin heterodimers requires a preformed nucleation seed that specifies subcellular localization and timing of microtubule polymerization in vivo. An evolutionarily conserved γ-tubulin-containing ring complex is recruited to the lateral wall of preexisting microtubules or outer nuclear membranes in plant cells, and is then activated as a template for new microtubules of defined geometry. Specific regulators are thought to target/activate the ring complex to nucleate nascent microtubules in distinct polymerization patterns, as seen in interphase and mitotic arrays. The augmin complex, which was initially identified in metazoan cells, recruits the ring complex to plant mitotic microtubules, where new polymers are abundantly generated at shallow angles.
动态极性微管由 13 个原丝组成，由 α-微管蛋白和 β-微管蛋白异二聚体组成，需要一个预先形成的成核种子，该种子指定体内微管聚合的亚细胞定位和时间。在植物细胞中，一个进化上保守的含有γ-微管蛋白的环复合物被招募到预先存在的微管或核外膜的侧壁上，然后被激活作为新的具有特定几何形状的微管的模板。人们认为特定的调节剂可以靶向/激活环复合物，以在不同的聚合模式下起始初生微管，如在间期中和有丝分裂排列中看到的那样。最初在后生动物细胞中鉴定的聚集体复合物将环复合物招募到植物有丝分裂微管中，在那里新的聚合物以浅角度大量生成。
