Nopp140 functions as a molecular link between the nucleolus and the coiled bodies.
Nopp140 functions as a molecular link between the nucleolus and the coiled bodies.
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NOPP140充当核仁与盘绕体之间的分子联系。
DOI：
10.1083/jcb.142.2.319
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发表时间：
1998-07-27
期刊：
影响因子：
--
通讯作者：
Meier UT
中科院分区：
文献类型：
--
作者：
Isaac C;Yang Y;Meier UT
卷曲体是高度富集小核RNA的小核细胞器，长期以来一直被认为与核仁相关。在这里，我们使用突变分析，瞬时转染，和酵母双杂交系统表明，核仁磷蛋白Nopp 140功能作为两个突出的核细胞器之间的分子联系。外源Nopp 140在核仁中迅速积累，但只有在一个滞后期后，在卷曲体，这表明两个细胞器之间的途径。部分Nopp140构建体的表达对内源性Nopp140产生显性负效应，通过将其和两种细胞器共有的其他抗原从核仁中追逐出来。Nopp 140的交替带正电荷和负电荷的重复结构域是靶向两个细胞器所必需的。此外，部分Nopp140结构引起形成新的结构在核质中，并在保守的羧基末端的情况下，导致分散的卷曲体。作为最后一个环节，我们确定了卷曲体特异性蛋白p80 coilin在酵母双杂交筛选与Nopp 140。通过免疫共沉淀证实了这两种蛋白质的相互作用。总之，Nopp 140似乎穿梭于核仁和卷曲体之间，并陪伴其他分子的运输。
Coiled bodies are small nuclear organelles that are highly enriched in small nuclear RNAs, and that have long been thought to be associated with the nucleolus. Here we use mutational analysis, transient transfections, and the yeast two-hybrid system to show that the nucleolar phosphoprotein Nopp140 functions as a molecular link between the two prominent nuclear organelles. Exogenous Nopp140 accumulated in the nucleolus rapidly, but only after a lag phase in coiled bodies, suggesting a pathway between the two organelles. The expression of partial Nopp140 constructs exerted dominant negative effects on the endogenous Nopp140 by chasing it and other antigens that were common to both organelles out of the nucleolus. The alternating positively and negatively charged repeat domain of Nopp140 was required for targeting to both organelles. In addition, partial Nopp140 constructs caused formation of novel structures in the nucleoplasm and, in the case of the conserved carboxy terminus, led to the dispersal of coiled bodies. As a final link, we identified the coiled body–specific protein p80 coilin in a yeast two-hybrid screen with Nopp140. The interaction of the two proteins was confirmed by coimmunoprecipitation. Taken together, Nopp140 appeared to shuttle between the nucleolus and the coiled bodies, and to chaperone the transport of other molecules.