The Glc7p nuclear phosphatase promotes mRNA export by facilitating association of Mex67p with mRNA
The Glc7p nuclear phosphatase promotes mRNA export by facilitating association of Mex67p with mRNA
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DOI：
10.1016/s1097-2765(04)00030-9
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发表时间：
2004-01-30
期刊：
影响因子：
16
通讯作者：
Guthrie, C
中科院分区：
文献类型：
--
作者：
Gilbert, W;Guthrie, C
mRNA输出由Mex 67 p：Mtr 2 p/NXF 1：p15介导，Mex 67 p：Mtr 2 p/NXF 1：p15是一种保守的异源二聚体输出受体，被认为通过RNA结合接头蛋白Yra 1 p/REF结合mRNA。Npl 3 p是S.啤酒。与哺乳动物SR蛋白一样，Npl 3 p被细胞质激酶丝氨酸磷酸化。在这里，我们报道了Npl 3 p的这种磷酸化是有效mRNA输出所需的。我们进一步表明，Npl 3 p的mRNA相关部分是未磷酸化的，这意味着随后的核去磷酸化事件。我们提出的证据表明，必要的，核磷酸酶Glc 7 p促进体内Npl 3 p的去磷酸化和Npl 3 p的核去磷酸化是mRNA输出所需的。具体而言，Mex 67 p向mRNA的募集是Glc 7 p依赖性的。我们提出了一个模型，其中一个周期的细胞质磷酸化和核去磷酸化穿梭SR衔接蛋白调节Mex 67 p：Mtr 2 p/NXF 1：p15依赖的mRNA出口。
mRNA export is mediated by Mex67p:Mtr2p/NXF1: p15, a conserved heterodimeric export receptor that is thought to bind mRNAs through the RNA binding adaptor protein Yra1p/REF. Recently, mammalian SR (serine/arginine-rich) proteins were shown to act as alternative adaptors for NXF1-dependent mRNA export. Npl3p is an SR-like protein required for mRNA export in S. cerevisiae. Like mammalian SR proteins, Npl3p is serine-phosphorylated by a cytoplasmic kinase. Here we report that this phosphorylation of Npl3p is required for efficient mRNA export. We further show that the mRNA-associated fraction of Npl3p is unphosphorylated, implying a subsequent nuclear dephosphorylation event. We present evidence that the essential, nuclear phosphatase Glc7p promotes dephosphorylation of Npl3p in vivo and that nuclear dephosphorylation of Npl3p is required for mRNA export. Specifically, recruitment of Mex67p to mRNA is Glc7p dependent. We propose a model whereby a cycle of cytoplasmic phosphorylation and nuclear dephosphorylation of shuttling SR adaptor proteins regulates Mex67p:Mtr2p/NXF1:p15-dependent mRNA export.