University of California, San Diego, Section of Cell and Developmental Biology, 9500 Gilman Dr., La Jolla, CA 92093-0116, USA.
J Cell Sci. 2011 Jan 15;124(Pt 2):270-9. doi: 10.1242/jcs.073676. Epub 2010 Dec 20.
TANGLED (TAN) is the founding member of a family of plant-specific proteins required for correct orientation of the division plane. Arabidopsis thaliana TAN is localized before prophase until the end of cytokinesis at the cortical division site (CDS), where it appears to help guide the cytokinetic apparatus towards the cortex. We show that TAN is actively recruited to the CDS by distinct mechanisms before and after preprophase band (PPB) disassembly. Colocalization with the PPB is mediated by one region of TAN, whereas another region mediates its recruitment to the CDS during cytokinesis. This second region binds directly to POK1, a kinesin that is required for TAN localization. Although this region of TAN is recruited to the CDS during cytokinesis without first colocalizing with the PPB, pharmacological evidence indicates that the PPB is nevertheless required for both early and late localization of TAN at the CDS. Finally, we show that phosphatase activity is required for maintenance of early but not late TAN localization at the CDS. We propose a new model in which TAN is actively recruited to the CDS by several mechanisms, indicating that the CDS is dynamically modified from prophase through to the completion of cytokinesis.
TANGLED(TAN)是植物特异性蛋白家族的创始成员之一,该蛋白家族对于正确的分裂面定向是必需的。拟南芥 TAN 定位于前期之前,直到皮层分裂位点(CDS)的胞质分裂结束,在那里它似乎有助于引导胞质分裂器朝向皮层。我们表明,TAN 通过在前期带(PPB)解组装之前和之后的不同机制被主动募集到 CDS。与 PPB 的共定位由 TAN 的一个区域介导,而另一个区域则在胞质分裂期间介导其募集到 CDS。第二个区域直接与 POK1 结合,POK1 是 TAN 定位所必需的驱动蛋白。尽管该区域的 TAN 在胞质分裂期间募集到 CDS 而不首先与 PPB 共定位,但药理学证据表明 PPB 对于 TAN 在 CDS 处的早期和晚期定位都是必需的。最后,我们表明,磷酸酶活性对于维持 CDS 处早期但不是晚期 TAN 定位是必需的。我们提出了一个新的模型,其中 TAN 通过几种机制被主动募集到 CDS,这表明 CDS 从前期到胞质分裂完成都在动态修饰。