Subcellular localization and RNP formation of IGF2BPs (IGF2 mRNA-binding proteins) is modulated by distinct RNA-binding domains
Subcellular localization and RNP formation of IGF2BPs (IGF2 mRNA-binding proteins) is modulated by distinct RNA-binding domains
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DOI：
10.1515/hsz-2013-0111
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发表时间：
2013-08-01
影响因子：
3.7
通讯作者：
Huettelmaier, Stefan
中科院分区：
文献类型：
--
作者：
Waechter, Kristin;Koehn, Marcel;Huettelmaier, Stefan
IGF 2 mRNA结合蛋白家族（IGF 2BPs）指导各种靶mRNA的细胞质命运并控制基本的细胞功能。在哺乳动物中表达的三种IGF 2BP旁系同源物包含两个RNA识别基序（RRM）以及四个KH结构域。这些结构域如何指导IGF 2BP旁系同源物依赖性蛋白质功能仍然很难理解。在这项研究中，我们分析的作用KH结构域IGF 2BP的突变GXXG-GEEG转换的单KH结构域环的背景下，全长多肽。这些分析表明，IGF 2BP 1和IGF 2BP 2的所有四个KH结构域基本上参与体外RNA结合和与RNA结合蛋白（RBP）的细胞缔合。此外，KH结构域防止这两个旁系同源物的核积累，并促进其招聘到应力颗粒。KH结构域在IGF 2BP 3中的作用似乎不太明显，因为所有四个KH结构域中的GxxG-GEEG转换仅适度影响该parabolic的RNA结合、亚细胞定位和RNA依赖性蛋白质缔合。这些发现表明IGF 2BP的旁系同源物依赖性RNA结合特性可能指导不同的细胞功能。我们的研究结果表明IGF 2BP通过所有四个KH结构域与靶RNA接触。这意味着重要的结构限制，这可能允许形成非常稳定的蛋白质-RNA复合物。
The IGF2 mRNA-binding protein family (IGF2BPs) directs the cytoplasmic fate of various target mRNAs and controls essential cellular functions. The three IGF2BP paralogues expressed in mammals comprise two RNA-recognition motifs (RRM) as well as four KH domains. How these domains direct IGF2BP paralogue-dependent protein function remains largely elusive. In this study, we analyze the role of KH domains in IGF2BPs by the mutational GXXG-GEEG conversion of single KH domain loops in the context of full-length polypeptides. These analyses reveal that all four KH domains of IGF2BP1 and IGF2BP2 are essentially involved in RNA-binding in vitro and the cellular association with RNA-binding proteins (RBPs). Moreover the KH domains prevent the nuclear accumulation of these two paralogues and facilitate their recruitment to stress granules. The role of KH domains appears less pronounced in IGF2BP3, because GxxG-GEEG conversion in all four KH domains only modestly affects RNA-binding, subcellular localization and RNA-dependent protein association of this paralogue. These findings indicate paralogue-dependent RNA-binding properties of IGF2BPs which likely direct distinct cellular functions. Our findings suggest that IGF2BPs contact target RNAs via all four KH domains. This implies significant structural constraints, which presumably allow the formation of exceedingly stable protein-RNA complexes.