Interplay between SRPK and Clk/Sty kinases in phosphorylation of the splicing factor ASF/SF2 is regulated by a docking motif in ASF/SF2
Interplay between SRPK and Clk/Sty kinases in phosphorylation of the splicing factor ASF/SF2 is regulated by a docking motif in ASF/SF2
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DOI：
10.1016/j.molcel.2005.08.025
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发表时间：
2005-10-07
期刊：
影响因子：
16
通讯作者：
Ghosh, G
中科院分区：
文献类型：
--
作者：
Ngo, JCK;Chakrabarti, S;Ghosh, G
SR蛋白ASF/SF 2的富含丝氨酸-丝氨酸（RS）的结构域被SR蛋白激酶（SRPK）和Clk/Sty激酶磷酸化。然而，这些激酶的磷酸化模式及其在ASF/SF 2生物调节中的协调作用尚不清楚。在这里，我们报告的晶体结构的活性片段的人SRPK 1绑定到一个肽来自SR蛋白。这种结构使我们确定了ASF/SF 2中的对接基序。我们发现，这种对接基序限制ASF/SF 2的磷酸化SRPK 1的RS结构域的N-末端的一部分-一个重要的属性，其组装成核斑点。我们进一步表明，Clk/Sty导致ASF/SF 2从斑点释放的C-末端部分的RS结构域的磷酸化。这些结果表明，ASF/SF 2的对接基序是SRPK 1和Clk/Sty连续磷酸化的关键调控元件，因此，是其亚细胞定位所必需的。
The arginine-serine (RS)-rich domain of the SR protein ASF/SF2 is phosphorylated by SR protein kinases (SRPKs) and Clk/Sty kinases. However, the mode of phosphorylation by these kinases and their coordination in the biological regulation of ASF/SF2 is unknown. Here, we report the crystal structure of an active fragment of human SRPK1 bound to a peptide derived from an SR protein. This structure led us to identify a docking motif in ASF/SF2. We find that this docking motif restricts phosphorylation of ASF/SF2 by SRPK1 to the N-terminal part of the RS domain - a property essential for its assembly into nuclear speckles. We further show that Clk/Sty causes release of ASF/SF2 from speckles by phosphorylating the C-terminal part of its RS domain. These results suggest that the docking motif of ASF/SF2 is a key regulatory element for sequential phosphorylation by SRPK1 and Clk/Sty and, thus, is essential for its subcellular localization.