A conserved Drosophila transportin-serine/arginine-rich (SR) protein permits nuclear import of Drosophila SR protein splicing factors and their antagonist repressor splicing factor 1
A conserved Drosophila transportin-serine/arginine-rich (SR) protein permits nuclear import of Drosophila SR protein splicing factors and their antagonist repressor splicing factor 1
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DOI：
10.1091/mbc.e02-02-0102
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发表时间：
2002-07-01
影响因子：
3.3
通讯作者：
Tazi, J
中科院分区：
文献类型：
--
作者：
Allemand, E;Dokudovskaya, S;Tazi, J
高度保守的富含丝氨酸/丝氨酸（SR）蛋白家族成员是参与后生动物mRNA前体剪接的核因子。在哺乳动物中，两种核输入受体，转运蛋白（TRN）-SR 1和TRN-SR 2，负责将SR蛋白靶向细胞核。果蝇和哺乳动物SR蛋白之间的核定位信号的独特功能促使我们研究果蝇SR蛋白及其拮抗剂阻遏剪接因子1（RSF 1）被导入细胞核的机制。在这里，我们报告的鉴定和表征的果蝇importin β家族蛋白（dTRN-SR），同源TRN-SR 2，特异性相互作用SR蛋白和RSF 1。dTRN-SR在细胞质和细胞核中具有广泛的定位，而N-末端缺失突变体与SR蛋白在核斑点中共定位。远Western实验证实，SR蛋白的RS结构域和RSF 1的GRS结构域是与dTRN-SR直接相互作用所必需的，这种相互作用可以通过磷酸化来调节。使用酵母模型系统，其中果蝇SR蛋白和RSF 1的核输入受损，我们证明了与dTRN-SR互补足以将这些蛋白质靶向细胞核。总之，这些结果意味着SR蛋白被导入细胞核的机制在果蝇和人类之间是保守的。
Members of the highly conserved serine/arginine-rich (SR) protein family are nuclear factors involved in splicing of metazoan mRNA precursors. In mammals, two nuclear import receptors, transportin (TRN)-SR1 and TRN-SR2, are responsible for targeting SR proteins to the nucleus. Distinctive features in the nuclear localization signal between Drosophila and mammalian SR proteins prompted us to examine the mechanism by which Drosophila SR proteins and their antagonist repressor splicing factor 1 (RSF1) are imported into nucleus. Herein, we report the identification and characterization of a Drosophila importin beta-family protein (dTRN-SR), homologous to TRN-SR2, that specifically interacts with both SR proteins and RSF1. dTRN-SR has a broad localization in the cytoplasm and the nucleus, whereas an N-terminal deletion mutant colocalizes with SR proteins in nuclear speckles. Far Western experiments established that the RS domain of SR proteins and the GRS domain of RSF1 are required for the direct interaction with dTRN-SR, an interaction that can be modulated by phosphorylation. Using the yeast model system in which nuclear import of Drosophila SR proteins and RSF1 is impaired,, we demonstrate that complementation with dTRN-SR is sufficient to target these proteins to the nucleus. Together, the results imply that the mechanism by which SR proteins are imported to the nucleus is conserved between Drosophila and humans.