Dogterom M, Maggs A C, Leibler S
Department of Physics, Princeton University, NJ 08544, USA.
Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):6683-8. doi: 10.1073/pnas.92.15.6683.
Microtubule asters forming the mitotic spindle are assembled around two centrosomes through the process of dynamic instability in which microtubules alternate between growing and shrinking states. By modifying the dynamics of this assembly process, cell cycle enzymes, such as cdc2 cyclin kinases, regulate length distributions in the asters. It is believed that the same enzymes control the number of assembled microtubules by changing the "nucleating activity" of the centrosomes. Here we show that assembly of microtubule asters may be strongly altered by effects connected with diffusion of tubulin monomers. Theoretical analysis of a simple model describing assembly of microtubule asters clearly shows the existence of a region surrounding the centrosome depleted in GTP tubulin. The number of assembled microtubules may in some cases be limited by this depletion effect rather than by the number of available nucleation sites on the centrosome.
形成有丝分裂纺锤体的微管星状体是通过动态不稳定性过程围绕两个中心体组装而成的，在这个过程中微管在生长和收缩状态之间交替。通过改变这种组装过程的动力学，细胞周期酶，如cdc2细胞周期蛋白激酶，调节星状体中的长度分布。人们认为，相同的酶通过改变中心体的“成核活性”来控制组装微管的数量。在这里，我们表明微管星状体的组装可能会受到与微管蛋白单体扩散相关的效应的强烈影响。对描述微管星状体组装的简单模型的理论分析清楚地表明，在中心体周围存在一个GTP微管蛋白耗尽的区域。在某些情况下，组装微管的数量可能受这种耗尽效应的限制，而不是受中心体上可用成核位点数量的限制。
