Signal recognition particle RNA localization within the nucleolus differs from the classical sites of ribosome synthesis
Signal recognition particle RNA localization within the nucleolus differs from the classical sites of ribosome synthesis
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DOI：
10.1083/jcb.200208037
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发表时间：
2002-11-11
影响因子：
7.8
通讯作者：
Pederson, T
中科院分区：
文献类型：
--
作者：
Politz, JC;Lewandowski, LB;Pederson, T
核仁是核糖体生物合成的场所，但现在已知还有其他功能。在本研究中，我们研究了核核内信号识别颗粒（SRP） RNA的分布与核糖体RNA合成、加工和新生核糖体组装的已知位点（即纤原中心、致密纤原成分（DFC）和颗粒成分）之间的关系。根据RNA聚合酶i特异性上游结合因子和蛋白纤维蛋白的定义，在纤维中心或核核的DFC中检测到很少的SRP RNA。一些SRP RNA存在于颗粒成分中，如蛋白质B23所示，表明在成熟后期可能与核糖体亚基相互作用。然而，在核仁中也检测到相当一部分SRP RNA，其中B23、UBF或纤维蛋白都不集中。双探针原位杂交实验证实，相当一部分核核SRP RNA在空间上与28S核糖体RNA不一致。这些结果表明，SRP RNA集中在核糖体生物合成的经典站点之外的核核内位置，这表明可能存在专门用于其他功能的核核区域。
The nucleolus is the site of ribosome biosynthesis, but is now known to have other functions as well. in the present study we have investigated how the distribution of signal recognition particle (SRP) RNA within the nucleolus relates to the known sites of ribosomal RNA synthesis, processing, and nascent ribosome assembly (i.e., the fibrillar centers, the dense fibrillar component (DFC), and the granular component). Very little SRP RNA was detected in fibrillar centers or the DFC of the nucleolus, as defined by the RNA polymerase I-specific upstream binding factor and the protein fibrillarin, respectively. Some SRP RNA was present in the granular component, as marked by the protein B23, indicating a possible interaction with ribosomal subunits at a later stage of maturation. However, a substantial portion of SRP RNA was also detected in regions of the nucleolus where neither B23, UBF, or fibrillarin were concentrated. Dual probe in situ hybridization experiments confirmed that a significant fraction of nucleolar SRP RNA was not spatially coincident with 28S ribosomal RNA. These results demonstrate that SRP RNA concentrates in an intranucleolar location other than the classical stations of ribosome biosynthesis, suggesting that there may be nucleolar regions that are specialized for other functions.