Heterogeneous nuclear ribonuclear protein K (hnRNPK) is an abundant RNA-binding protein crucial for a wide variety of biological processes. While its binding preference for multi-cytosine-patch (C-patch) containing RNA is well documented, examination of binding to known cellular targets that contain C-patches reveals an unexpected breadth of binding affinities. Analysis of in-cell crosslinking data reinforces the notion that simple C-patch preference is not fully predictive of hnRNPK localization within transcripts. The individual RNA-binding domains of hnRNPK work together to interact with RNA tightly, with the KH3 domain being neither necessary nor sufficient for binding. Rather, the RG/RGG domain is implicated in providing essential contributions to RNA-binding, but not DNA-binding, affinity. hnRNPK is essential for X chromosome inactivation, where it interacts with Xist RNA specifically through the Xist B-repeat region. We use this interaction with an RNA motif derived from this B-repeat region to determine the RNA-structure dependence of C-patch recognition. While the location preferences of hnRNPK for C-patches are conformationally restricted within the hairpin, these structural constraints are relieved in the absence of RNA secondary structure. Together, these results illustrate how this multi-domain protein's ability to accommodate and yet discriminate between diverse cellular RNAs allows for its broad cellular functions.

中文翻译：

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hnRNPK 识别 Xist 和其他生物 RNA 的 B 基序。

异质核核糖核蛋白 K (hnRNPK) 是一种丰富的 RNA 结合蛋白，对多种生物过程至关重要。虽然它对含有 RNA 的多胞嘧啶补丁 (C-patch) 的结合偏好有据可查，但检查与包含 C-补丁的已知细胞靶标的结合揭示了出乎意料的结合亲和力广度。细胞内交联数据的分析强化了这样一种观点，即简单的 C-patch 偏好不能完全预测转录本中的 hnRNPK 定位。hnRNPK 的单个 RNA 结合域共同作用以与 RNA 紧密相互作用，KH3 域对于结合既不必要也不充分。相反，RG/RGG 结构域涉及为 RNA 结合而非 DNA 结合亲和力提供重要贡献。hnRNPK 对 X 染色体失活至关重要，它通过 Xist B-repeat 区域特异性地与 Xist RNA 相互作用。我们使用这种与源自该 B 重复区域的 RNA 基序的相互作用来确定 C 补丁识别的 RNA 结构依赖性。虽然 hnRNPK 对 C 补丁的位置偏好在发夹内受到构象限制，但在没有 RNA 二级结构的情况下，这些结构限制得到缓解。总之，这些结果说明了这种多域蛋白质适应并区分不同细胞 RNA 的能力如何允许其广泛的细胞功能。虽然 hnRNPK 对 C 补丁的位置偏好在发夹内受到构象限制，但在没有 RNA 二级结构的情况下，这些结构限制得到缓解。总之，这些结果说明了这种多域蛋白质适应并区分不同细胞 RNA 的能力如何允许其广泛的细胞功能。虽然 hnRNPK 对 C 补丁的位置偏好在发夹内受到构象限制，但在没有 RNA 二级结构的情况下，这些结构限制得到缓解。总之，这些结果说明了这种多域蛋白质适应并区分不同细胞 RNA 的能力如何允许其广泛的细胞功能。