Boehringer Daniel, Makarov Evgeny M, Sander Bjoern, Makarova Olga V, Kastner Berthold, Lührmann Reinhard, Stark Holger
Max Planck Institute for Biophysical Chemistry, Department of Cellular Biochemistry, Am Fassberg 11, 37077 Goettingen, Germany.
Nat Struct Mol Biol. 2004 May;11(5):463-8. doi: 10.1038/nsmb761. Epub 2004 Apr 18.
Major structural changes occur in the spliceosome during its transition from the fully assembled complex B to the catalytically activated spliceosome. To understand the rearrangement, it is necessary to know the detailed three-dimensional structures of these complexes. Here, we have immunoaffinity-purified human spliceosomes (designated B Delta U1) at a stage after U4/U6.U5 tri-snRNP integration but before activation, and have determined the three-dimensional structure of B Delta U1 by single-particle electron cryomicroscopy at a resolution of approximately 40 A. The overall size of the complex is about 370 x 270 x 170 A. The three-dimensional structure features a roughly triangular body linked to a head domain in variable orientations. The body is very similar in size and shape to the isolated U4/U6.U5 tri-snRNP. This provides initial insight into the structural organization of complex B.
在剪接体从完全组装好的复合物B转变为催化激活的剪接体的过程中，会发生重大的结构变化。为了理解这种重排，有必要了解这些复合物的详细三维结构。在这里，我们通过免疫亲和纯化了处于U4/U6·U5三小核核糖核蛋白整合后但激活前阶段的人剪接体（命名为BΔU1），并通过单颗粒冷冻电子显微镜以约40埃的分辨率确定了BΔU1的三维结构。该复合物的整体尺寸约为370×270×170埃。三维结构的特征是一个大致呈三角形的主体，以可变方向连接到一个头部结构域。该主体在大小和形状上与分离的U4/U6·U5三小核核糖核蛋白非常相似。这为复合物B的结构组织提供了初步见解。
