Cook C R, McNally M T
Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Nucleic Acids Res. 1996 Dec 15;24(24):4962-8. doi: 10.1093/nar/24.24.4962.
We have characterized an RNP complex that assembles in nuclear extracts on the negative regulator of splicing (NRS) element from Rous sarcoma virus. While no complex was detected by native gel electrophoresis under conditions that supported spliceosome assembly, gel filtration revealed a specific ATP-independent complex that rapidly assembled on NRS RNA. No complexes were formed on non-specific RNA. Unlike the non-specific H complex, factors required for NRS complex assembly are limiting in nuclear extract. The NRS complex was not detected in reactions containing ATP and pre-formed complexes were dissociated in the presence of ATP. In addition, the assembly process was sensitive to high salt but NRS complexes were salt stable once formed. Assembly of the NRS complex appears functionally significant since mutated NRS RNAs that fail to inhibit splicing in vivo are defective for NRS complex assembly in nuclear extract. The probable relationship of the NRS complex to spliceosomal complexes is discussed.
我们已对一种核糖核蛋白（RNP）复合物进行了表征，该复合物在核提取物中于来自劳氏肉瘤病毒的剪接负调控元件（NRS）上组装。虽然在支持剪接体组装的条件下，天然凝胶电泳未检测到复合物，但凝胶过滤显示出一种特定的不依赖ATP的复合物，它能在NRS RNA上快速组装。在非特异性RNA上未形成复合物。与非特异性H复合物不同，NRS复合物组装所需的因子在核提取物中是有限的。在含有ATP的反应中未检测到NRS复合物，并且预先形成的复合物在ATP存在下会解离。此外，组装过程对高盐敏感，但NRS复合物一旦形成则对盐稳定。NRS复合物的组装似乎具有功能意义，因为在体内未能抑制剪接的突变NRS RNA在核提取物中进行NRS复合物组装时存在缺陷。本文还讨论了NRS复合物与剪接体复合物之间可能的关系。
