Phosphorylation by Sky1p promotes Npl3p shuttling and mRNA dissociation
Phosphorylation by Sky1p promotes Npl3p shuttling and mRNA dissociation
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DOI：
10.1017/s1355838201002369
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发表时间：
2001-02-01
期刊：
影响因子：
4.5
通讯作者：
Guthrie, C
中科院分区：
文献类型：
--
作者：
Gilbert, W;Siebel, CW;Guthrie, C
目前认为哺乳动物 SR 蛋白在 mRNA 输出和剪接中发挥作用。它们含有多种磷酸化丝氨酸/精氨酸 (RS/SR) 二肽。尽管 SR 结构域可以在体外被许多激酶磷酸化，但生理相关的激酶以及这些修饰在体内的作用仍不清楚。 NpI3 是芽殖酵母中的一种穿梭蛋白，我们之前证明它是哺乳动物 SR 蛋白激酶 SRPK1 以及相关酵母激酶 Sky1 的底物。在这里，我们证明 Sky1p 仅磷酸化 NpI3p 的八个 SR/RS 二肽中的一个。 C 端 RS 突变为 RA，或 SKY1 缺失，导致 NpI3p 在细胞质中积聚。Npl3p 的重新分布伴随着体内与 Poly(A)(+) RNA 的结合增加，以及与其输入受体 Mtr10p 的结合减少。我们认为，NpI3p 被细胞质定位的 Sky1p 磷酸化是输出终止时 mRNA 有效释放所必需的。
Mammalian SR proteins are currently thought to function in mRNA export as well as splicing. They contain multiple phosphorylated serine/arginine (RS/SR) dipeptides. Although SR domains can be phosphorylated by many kinases in vitro, the physiologically relevant kinase(s), and the role(s) of these modifications in vivo have remained unclear. NpI3 is a shuttling protein in budding yeast that we showed previously to be a substrate for the mammalian SR protein kinase, SRPK1, as well as the related yeast kinase, Sky1, Here we demonstrate that Sky1p phosphorylates only one of NpI3p's eight SR/RS dipeptides. Mutation of the C-terminal RS to RA, or deletion of SKY1, results in the cytoplasmic accumulation of NpI3p, The redistribution of Npl3p is accompanied by its increased association with poly(A)(+) RNA and decreased association with its import receptor, Mtr10p, in vivo. We propose that phosphorylation of NpI3p by the cytoplasmically localized Sky1p is required for efficient release of mRNA upon termination of export.