Regulation of mitosis by kinetochore-dependent mechanisms

动舞依赖性机制对有丝分裂的调节S.酿酒酵母CLASP，Stu 1，通过定位于微管和（通过其第一个TOGL结构域）以相位依赖性方式定位于动粒来协调有丝分裂。在分裂中期，Stu 1定位于动粒，并以张力依赖的方式稳定动粒微管。此外，Stu 1定位于极间微管的晶格，并通过其第二个TOGL结构域的活性和最有可能通过交联极间微管来稳定中期纺锤体。在分裂后期，Stu 1从动粒上解离，因此可能使分裂后期A典型的动粒微管缩短。Stu 1也从MT晶格中解离并定位于纺锤体中间区。这仍然允许微管通过第二TOGL结构域稳定化，并且很可能促进微管交联以允许在后期滑动。在前中期，Stu 1被隔离在独立的动粒上。这可以防止早熟纺锤体的形成，并可能促进这些动粒的捕获。Stu 1定位到未连接的动粒的依赖性让人想起那些促进纺锤体组装检查点（SAC）蛋白在未连接的动粒的定位的依赖性。此外，Stu 1通过第一个TOGL结构域与SAC蛋白Mad 1相互作用。在未来的研究中，我们计划探讨Stu 1定位的原理：1）中期与后期着丝粒和微管定位的调节。2)与Stu 1的第一个TOGL结构域相互作用的动粒蛋白的鉴定。3)蛋白激酶Mps 1的底物和磷酸化位点对于Stu 1在未连接动粒上的隔离至关重要。4)在未连接的动粒上导致螯合效应的机制（诱导构象变化？）。进一步研究Stu 1在有丝分裂中的作用：1）Stu 1定位于中期着丝粒时，促进着丝粒微管稳定的机制。2)Stu 1促进捕获未连接的动粒的机制。3)Stu 1-Mad 1相互作用的作用。

Regulation of mitosis by kinetochore-dependent mechanisms The S. cerevisiae CLASP, Stu1, orchestrates mitosis by localizing to microtubules and (via its first TOGL domain) to kinetochores in a phase-dependent manner. In metaphase Stu1 localizes to kinetochores and stabilizes kinetochore microtubules in a tension-dependent manner. Furthermore, Stu1 localizes to the lattice of interpolar microtubules and stabilizes the metaphase spindle via the activity of its second TOGL domain and most likely by crosslinking the interpolar microtubules. In anaphase Stu1 dissociates from kinetochores and thus possibly allows the shortening of kinetochore microtubules typical for anaphase A. Stu1 also dissociates from the MT lattice and localizes to the spindle midzone. This still allows microtubule stabilization via the second TOGL domain and most likely alleviates microtubule crosslinking to allow gliding in anaphase. In prometaphase Stu1 gets sequestered at unattached kinetochores. This prevents precocious spindle formation and possibly facilitates capturing of these kinetochores. The dependencies of the Stu1 localization to unattached kinetochores are reminiscent of those that facilitate the localization of spindle assembly checkpoint (SAC) proteins at unattached kinetochores. Moreover Stu1 interacts with the SAC protein Mad1 via the first TOGL domain. In the future we plan to investigate the principles of Stu1 localization: 1) The regulation of kinetochore and microtubule localization in metaphase versus anaphase. 2) The identification of the kinetochore proteins that interact with the first TOGL domain of Stu1. 3) The substrates and phosphorylation sites of the protein kinase Mps1 that is essential for the sequestering of Stu1 at unattached kinetochores. 4) The mechanism that leads to the sequestering effect at unattached kinetochores (induction of a conformational change?). Furthermore we plan to investigate the manifested and putative roles of Stu1 in mitosis: 1) The mechanism that facilitates stabilization of kinetochore microtubules when Stu1 localizes to metaphase kinetochores. 2) The mechanism by which Stu1 promotes capturing of unattached kinetochores. 3) The role of the Stu1-Mad1 interaction.