The multifunctional protein YB-1 has previously been shown to be the only protein of the cytoplasmic extract of HEK293 cells, which is able to specifically interact with imperfect RNA hairpins containing motifs that are often found in exosomal (e) RNAs. In addition, it has been revealed that similar hairpins formed by degenerate consensus sequences corresponding to three eRNA-specific motifs are responsible for the cooperative binding of YB-1 to RNA in vitro. Here, using the photoactivatable ribonucleoside-enhanced cross-linking and immunoprecipitation method applied to HEK293 cells producing FLAG-labeled YB-1, we identified mRNAs cross-linked to YB-1 in vivo and then carried out a search for the aforementioned sequences in the regions of the YB-1 cross-linking sites. It turned out that many of the mRNAs found cross-linked to YB-1 encode proteins associated with various regulatory processes, including responses to stress. More than half of all cross-linked mRNAs contained degenerate consensus sequences, which were preferably located in 3'-untranslated regions (UTRs), where most of the YB-1 cross-linking sites appeared, although not close to these sequences. Furthermore, YB-1 was mainly cross-linked to those mRNAs with degenerate consensus sequences, which could be classified as packaged because their translation levels were low compared to cellular levels. This suggests that the cooperative binding of YB-1 to mRNAs through the above sequences probably triggers the well-known multimerization of YB-l, leading to the packaging of these mRNAs. Thus, our findings indicate a previously unknown link between the degenerate consensus sequences present in the 3'-UTRs of many cytoplasmic mRNAs and YB-1-mediated translational silencing.

中文翻译：

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在细胞mRNA的3'-非翻译区中的简并共有序列作为可能参与这些mRNA的YB-1介导的包装的特定基序。

多功能蛋白质YB-1先前已被证明是HEK293细胞胞质提取物中的唯一蛋白质，它能够与不完整的RNA发夹特异性相互作用，该发夹含有在外泌体（e）RNA中经常发现的基序。另外，已经揭示了由简并共有序列形成的相似发夹，所述简并共有序列对应于三个eRNA特异性基序，其负责体外YB-1与RNA的协同结合。在这里，使用可光活化的核糖核苷增强的交联和免疫沉淀方法，将其应用于产生FLAG标记的YB-1的HEK293细胞，我们在体内鉴定了与YB-1交联的mRNA，然后在细胞中搜索上述序列。 YB-1交联位点的区域。结果发现，发现许多与YB-1交联的mRNA编码与各种调节过程相关的蛋白质，包括对应激的反应。所有交联的mRNA中，有一半以上包含简并共有序列，它们优选位于3'-非翻译区（UTR），虽然大多数YB-1交联位点与这些序列不接近，但在这些区域中大多数出现。此外，YB-1主要与简并共有序列的那些mRNA交联，可以将它们归类为包装的，因为它们的翻译水平比细胞水平低。这表明YB-1通过上述序列与mRNA的协同结合可能触发了YB-1的众所周知的多聚，导致这些mRNA的包装。从而，