Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
Nucleic Acids Res. 2010 Jun;38(10):3351-61. doi: 10.1093/nar/gkq033. Epub 2010 Feb 2.
The REF/ALY mRNA export adaptor binds TAP/NXF1 via an arginine-rich region, which overlaps with its RNA-binding domain. When TAP binds a REF:RNA complex, it triggers transfer of the RNA from REF to TAP. Here, we have examined the effects of arginine methylation on the activities of the REF protein in mRNA export. We have mapped the arginine methylation sites of REF using mass spectrometry and find that several arginines within the TAP and RNA binding domains are methylated in vivo. However, arginine methylation has no effect on the REF:TAP interaction. Instead, arginine methylation reduces the RNA-binding activity of REF in vitro and in vivo. The reduced RNA-binding activity of REF in its methylated state is essential for efficient displacement of RNA from REF by TAP in vivo. Therefore, arginine methylation fine-tunes the RNA-binding activity of REF such that the RNA-protein interaction can be readily disrupted by export factors further down the pathway.
REF/ALY mRNA 输出衔接子通过富含精氨酸的区域与 TAP/NXF1 结合，该区域与 RNA 结合域重叠。当 TAP 结合 REF:RNA 复合物时，它会触发 RNA 从 REF 转移到 TAP。在这里，我们研究了精氨酸甲基化对 mRNA 输出中 REF 蛋白活性的影响。我们使用质谱法绘制了 REF 的精氨酸甲基化位点图谱，发现 TAP 和 RNA 结合域内的几个精氨酸在体内被甲基化。然而，精氨酸甲基化对 REF:TAP 相互作用没有影响。相反，精氨酸甲基化降低了 REF 在体外和体内的 RNA 结合活性。在 REF 的甲基化状态下，其 RNA 结合活性降低对于 TAP 在体内有效地从 REF 上置换 RNA 是必需的。因此，精氨酸甲基化精细调节 REF 的 RNA 结合活性，使得 RNA-蛋白相互作用可以很容易地被途径下游的出口因子破坏。
