mRNA binding protein mrnp 41 localizes to both nucleus and cytoplasm
mRNA binding protein mrnp 41 localizes to both nucleus and cytoplasm
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DOI：
10.1073/pnas.94.17.9119
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发表时间：
1997-08-19
影响因子：
11.1
通讯作者：
Blobel, G
中科院分区：
文献类型：
--
作者：
Kraemer, D;Blobel, G
我们已经鉴定出一种分子量为40880道尔顿的人类蛋白质，并对其进行了分子特性分析。在对海拉细胞进行紫外线照射后，这种蛋白质与含多聚腺苷酸的信使核糖核酸（mRNA）交联，因此被命名为mrnp41（代表41千道尔顿的mRNA结合蛋白）。细胞分级分离和免疫印迹显示，mrnp41存在于细胞质和细胞核中，尤其在核膜中。免疫荧光显微镜观察发现，mrnp41定位于核质中的特定区域、核边缘以及整个细胞质中的网状结构。分别用破坏肌动蛋白丝或微管的药物细胞松弛素或诺考达唑预先处理细胞后，细胞质网状结构的染色被破坏，这表明mrnp41与细胞骨架有关。用针对mrnp41和细胞质多聚腺苷酸结合蛋白的抗体进行双重免疫荧光实验，结果显示它们共定位于细胞质网状结构。免疫金电子显微镜证实了mrnp41在细胞质和核质中的定位，并显示出核孔复合物有显著的标记。综合这些数据表明，mrnp41可能在信使核糖核蛋白颗粒（mRNPs）的核输出以及/或者在细胞骨架上的细胞质运输或附着过程中发挥作用。先前有报道称，粟酒裂殖酵母中被命名为Rae1p的mrnp41同源物，或者酿酒酵母中被命名为Gle2p的同源物发生突变，会导致mRNA在细胞核中积累，这与mrnp41在核输出中的作用是一致的，尽管目前尚不清楚这些同源物是否也是mRNA结合蛋白。
We have identified and molecularly characterized a human protein with a M-r of 40,880 Da, After UV irradiation of HeLa cells, this protein was cross-linked to poly(A)-containing mRNA and was therefore designated mrnp 41 (for mRNA binding protein of 41 kDa), Cell fractionation and immunoblotting showed mrnp 41 in both the cytoplasm and the nucleus and particularly in the nuclear envelope. Immunofluorescence microscopy localized mrnp 41 to distinct foci in the nucleoplasm, to the nuclear rim, and to meshwork-like structures throughout the cytoplasm, The cytoplasmic meshwork staining was disrupted by prior treatment of cells with the actin filament-or microtubule-disrupting drugs cytochalasin or nocodazole, respectively, suggesting association of mrnp 41 with the cytoskeleton, Double immunofluorescence with antibodies against mrnp 41 and the cytoplasmic poly(A) binding protein showed colocalization to the cytoplasmic meshwork, Immunogold electronmicroscopy confirmed mrnp 41's cytoplasmic and nucleoplasmic localization and revealed a striking labeling of nuclear pore complexes, Together these data suggest that mrnp 41 may function in nuclear export of mRNPs and/or in cytoplasmic transport on, or attachment to, the cytoskeleton, Consistent with a role of mrnp 41 in nuclear export are previous reports that mutations in homologs of mrnp 41 in Schizosaccharomyces pombe, designated Rae1p, or in Saccharomyces cerevisiae, designated Gle2p, result in mRNA accumulation in the nucleus although it is presently not known whether these homologs are mRNA binding proteins as well.