The nuclear cap-binding complex (CBC), a heterodimer comprised of a 20 kDa subunit (CBP20) and an 80 kDa regulatory subunit (CBP80), binds to nascent RNA polymerase II transcripts and is important throughout different aspects of RNA metabolism. In a recent publication, using a combination of X-ray crystallographic information, mutagenesis studies, small-angle scattering experiments, analytical ultracentrifugation and in vivo assays, we presented evidence that importin-α and importin-β, two nucleocytoplasmic transport proteins, play key roles in regulating the binding of capped RNA by the CBC in cells. A model for how complexes between CBC and the importins cycle in and out of the nucleus and direct the proper positional binding and release of capped RNA is presented here and is discussed in light of recent publications.

中文翻译：

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在细胞质中卸载 RNA：一项“导入”任务

核帽结合复合物 (CBC) 是一种异二聚体，由 20 kDa 亚基 (CBP20) 和 80 kDa 调节亚基 (CBP80) 组成，与新生的 RNA 聚合酶 II 转录物结合，在 RNA 代谢的不同方面都很重要。在最近的一份出版物中，结合 X 射线晶体学信息、诱变研究、小角散射实验、分析超速离心和体内测定，我们提出了证据表明 importin-α 和 importin-β，两种核质转运蛋白，起关键作用在调节细胞中 CBC 与加帽 RNA 的结合中的作用。此处介绍了 CBC 和输入蛋白之间的复合物如何循环进出细胞核并指导加帽 RNA 的正确位置结合和释放的模型，并根据最近的出版物进行了讨论。