Fury M G, Zhang W, Christodoulopoulos I, Zieve G W
Department of Pathology, SUNY Stony Brook School of Medicine 11794-8691, USA.
Exp Cell Res. 1997 Nov 25;237(1):63-9. doi: 10.1006/excr.1997.3750.
The snRNP core proteins (B, D3, D2, D1, E, F, and G) assemble with snRNA and form the snRNP core particle with a suggested stoichiometry of B2[D1, D2(E, F, G)2]D3. The newly synthesized snRNP core proteins are stored in the cytoplasm in three RNA-free complexes of (1) B at 2S-6S; (2) [D1, D2(E, F, G)2] at 6S; and (3) (B, D3, and 69 kDa) at 20S. The snRNP proteins assemble stepwise with snRNAs that appear transiently in the cytoplasm before returning to the nucleus as mature snRNP particles. In this report, two approaches are used to investigate the protein:protein interactions between the snRNP proteins. First, the 6S and 20S cytoplasmic complexes chromatographed as intact structures, supporting their identifications as discrete complexes. Second, the cDNAs for the proteins were used to test all pair-wise interactions between the seven major core proteins using the yeast two-hybrid system. The two-hybrid system identified four strong reciprocal interactions, one weak reciprocal interaction, five one-way interactions, and one homotypic interaction. The strongest interactions were between proteins within the 6S particle. Other interactions were between proteins in the 6S and 20S particles or within the 20S particle itself. These interactions are likely to occur within the cytoplasmic snRNP core protein complexes and the mature snRNP particle.
小核核糖核蛋白（snRNP）核心蛋白（B、D3、D2、D1、E、F和G）与小核RNA（snRNA）组装，形成化学计量比为B2[D1, D2(E, F, G)2]D3的snRNP核心颗粒。新合成的snRNP核心蛋白以三种无RNA复合物的形式储存在细胞质中：（1）2S - 6S的B；（2）6S的[D1, D2(E, F, G)2]；（3）20S的（B、D3和69 kDa）。snRNP蛋白与在细胞质中短暂出现然后作为成熟snRNP颗粒返回细胞核的snRNA逐步组装。在本报告中，使用两种方法研究snRNP蛋白之间的蛋白质：蛋白质相互作用。首先，6S和20S细胞质复合物以完整结构进行色谱分离，支持将它们鉴定为离散复合物。其次，使用酵母双杂交系统，利用蛋白质的cDNA测试七种主要核心蛋白之间的所有成对相互作用。双杂交系统鉴定出四种强相互作用、一种弱相互作用、五种单向相互作用和一种同型相互作用。最强的相互作用发生在6S颗粒内的蛋白质之间。其他相互作用发生在6S和20S颗粒中的蛋白质之间或20S颗粒本身内部。这些相互作用可能发生在细胞质snRNP核心蛋白复合物和成熟snRNP颗粒内。
