中文摘要：

Dvl（Dishevelled）是Wnt信号通路传递的核心分子,无论内源的还是过表达的Dvl在细胞体内都能因自聚而形成puncta.研究已报道,Dvl主要通过其DIX结构域上的三个作用区域来介导自聚：SiteⅠ、SiteⅡ和SiteⅢ,其中SiteⅠ和SiteⅡ还参与了Dvl-DIX与Ccd1-DIX的异聚.为了进一步得到Dvl2-DIX上SiteⅠ和SiteⅡ的直接三维结构,本研究设计了一系列的SiteⅢ突变体.通过体内和体外实验进一步证实了这些突变氨基酸确实参与了Dvl2-DIX的自聚,然后对这些SiteⅢ突变体蛋白成功地进行了纯化和结晶,最终得到3.1魡的Dvl2-DIX（G65A）晶体数据.分析表明该晶体存在片层位移现象,需对数据进行一定修正后才能进行后续的结构分析.体外实验又证实了这些突变氨基酸不影响Dvl2-DIX与Ccd1-DIX的异聚,为了进一步研究Dvl2-DIX与Ccd1-DIX相互作用,我们对这些SiteⅢ突变体蛋白与Ccd1-DIX进行共结晶.最终获得Dvl2-DIX（G65A）与Ccd1-DIX复合物的初晶,利于进一步的晶体优化及数据收集.

英文摘要：

Dvl （Dishevelled） is a key effector molecule of the Wnt signaling pathway. The DIX domain of Dvl （Dvl-DIX） can homo-oligomerize into cytoplasmic puncta via the intra-filament Site Ⅰ , Site Ⅱ and the interfilament Site Ⅲ, and form hetero-complex with the DIX domain of Ccdl （Ccdl-DIX） through Site Ⅰ and Site Ⅱ. Since all efforts to solve the wildtype Dvl2-DIX structure were unsuccessful, we carried out crystallization trials with the Site m mutants of Dvl2-DIX that display impaired homo-oligomerization and Wnt activity. Crystals of Dv12-DIX（G65A） protein were obtained, but the diffraction data encountered an unexpected lattice-translocation defect. These Site Ⅲ mutations of Dvl2-DIX retained the ability to hetero-interact with Ccdl-DIX, and we thus successfully generated various complexes between Dvl2-DIX mutants and wildtype Ccdl-DIX. After extensive trials, crystals of the Dv12-DIX（G65A）-Ccdl-DIX complex were produced, but of poor quality and unsuitable for diffraction studies. Optimization is under way.