在真核生物体内，剪切体在细胞核内负责真核信使RNA的内含子的剪切和外显子的拼接。剪切体的核心是小核核糖核蛋白(snRNP)。snRNP在细胞质中由小核RNA(snRNA)及与之相结合的蛋白质组成。snRNP在细胞质中处理，关键一步需要Sm七元复合物组装在snRNA的特定位点上。运动神经元生存蛋白SMN为中心的复合物帮助Sm复合物正确组装在snRNA上形成snRNP。SMN复合物内部有多个亚复合物，包括Gemin3-Gemin4-Gemin5和Gemin6-Gemin7-Gemin8-UNRIP。亚复合物内部相互作用，以及这两个亚复合物在SMN复合物装配Sm复合物在snRNA上中的作用还不清楚。本研究计划综合生物化学，生物物理学以及X射线晶体衍射技术研究两个亚复合物内部蛋白质相互作用，进一步理解SMN复合物中的蛋白质是如何协同结合snRNA和Sm蛋白质复合物来完成snRNP装配过程的。

In nucleus, spliceosome is responsible for the splicing of introns and the removal of the introns in eykaryotic mRNA. The core component of the spliceosome is snRNP, which consists of snRNA and its associated protein factors. The snRNP is processed in cytoplasm, which requires the assembly of Sm heptameric ring complex at the Sm binding site within the snRNA. The survival of motor neuron (SMN) complex facilitates the assembly of Sm on snRNA and the formation of snRNP. Several sub complexes exist in SMN complex, including Gemin3-Gemin4-Gemin5 and Gemin6-Gemin7-Gemin8-UNRIP. The interaction network between each sub-complex, as well as the roles the sub-complexes play, are largely unknown. The proposed research plan will utilize the biochemical, biophysical technique, as well as X-ray crystallography to investigate the protein-protein interactions in the two sub-complexes and how the proteins in SMN complex coordinate to bind snRNA and Sm complex to complete the assembly process.