Battle Daniel J, Lau Chi-Kong, Wan Lili, Deng Hongying, Lotti Francesco, Dreyfuss Gideon
Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Mol Cell. 2006 Jul 21;23(2):273-9. doi: 10.1016/j.molcel.2006.05.036.
The survival of motor neurons protein (SMN) is part of a large complex that contains six other proteins, Gemins2-7. The SMN complex assembles the heptameric Sm protein core on small nuclear RNAs (snRNAs) and plays a critical role in the biogenesis of snRNPs, the major and essential components of mRNA splicing in eukaryotes. For its function, the SMN complex binds Sm proteins and snRNAs, which it distinguishes from other RNAs by specific features they contain. We show here that Gemin5, a 170 kDa WD-repeat protein, is the snRNA binding protein of the SMN complex. Gemin5 binds directly and specifically to the unique features, including the Sm site, of snRNAs. Reduction of Gemin5 results in reduced capacity of the SMN complex to bind snRNAs and to assemble Sm cores. Gemin5 therefore functions as the factor that allows the SMN complex to distinguish snRNAs from other cellular RNAs for snRNP biogenesis.
运动神经元存活蛋白（SMN）是一个大型复合体的一部分，该复合体还包含其他六种蛋白质，即Gemins2 - 7。SMN复合体在小核RNA（snRNA）上组装七聚体Sm蛋白核心，并在小核核糖核蛋白（snRNP）的生物合成中起关键作用，snRNP是真核生物中mRNA剪接的主要和必需成分。就其功能而言，SMN复合体结合Sm蛋白和snRNA，它通过snRNA所含的特定特征将其与其他RNA区分开来。我们在此表明，170 kDa的WD重复蛋白Gemin5是SMN复合体的snRNA结合蛋白。Gemin5直接且特异性地结合snRNA的独特特征，包括Sm位点。Gemin5的减少导致SMN复合体结合snRNA和组装Sm核心的能力降低。因此，Gemin5作为一种因子，使SMN复合体在snRNP生物合成过程中能够将snRNA与其他细胞RNA区分开来。
