Nup98 is a mobile nucleoporin with transcription-dependent dynamics
Nup98 is a mobile nucleoporin with transcription-dependent dynamics
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DOI：
10.1091/mbc.01-11-0538
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发表时间：
2002-04-01
影响因子：
3.3
通讯作者：
Powers, MA
中科院分区：
文献类型：
--
作者：
Griffis, ER;Altan, N;Powers, MA
核孔蛋白98（Nup98）是一种含有甘氨酸 - 亮氨酸 - 苯丙氨酸 - 甘氨酸（GLFG）氨基酸重复序列的核孔蛋白，在核运输中起关键作用。将抗Nup98的抗体注射到细胞核中会阻断大多数RNA的输出。Nup98包含几个运输因子的结合位点；然而，这种核孔蛋白发挥作用的机制仍不清楚。已提出Nup98有多种亚细胞定位。在此我们表明，Nup98确实在核孔复合体和细胞核内都存在。在细胞核内，Nup98与一种新的核结构相关联，我们将其称为GLFG小体，因为Nup98的GLFG结构域是靶向该结构所必需的。对活细胞中绿色荧光蛋白 - Nup98进行光漂白显示，Nup98是可移动的，并且在这些不同的定位之间移动。光漂白后的恢复速率表明，Nup98与核质中其他移动性较差的成分相互作用。令人惊讶的是，鉴于先前与核输出的联系，Nup98在细胞核内和核孔处的移动性取决于RNA聚合酶I和II正在进行的转录。这些数据产生了一个模型，其中Nup98有助于将RNA导向核孔，并为可移动核孔蛋白的作用提供了第一种潜在机制。
Nucleoporin 98 (Nup98), a glycine-leucine-phenylalanine-glycine (GLFG) amino acid repeat-containing nucleoporin, plays a critical part in nuclear trafficking. Injection of antibodies to Nup98 into the nucleus blocks the export of most RNAs. Nup98 contains binding sites for several transport factors; however, the mechanism by which this nucleoporin functions has remained unclear. Multiple subcellular localizations have been suggested for Nup98. Here we show that Nup98 is indeed found both at the nuclear pore complex and within the nucleus. Inside the nucleus, Nup98 associates with a novel nuclear structure that we term the GLFG body because the GLFG domain of Nup98 is required for targeting to this structure. Photobleaching of green fluorescent protein-Nup98 in living cells reveals that Nup98 is mobile and moves between these different localizations. The rate of recovery after photobleaching indicates that Nup98 interacts with other, less mobile, components in the nucleoplasm. Strikingly, given the previous link to nuclear export, the mobility of Nup98 within the nucleus and at the pore is dependent on ongoing transcription by RNA polymerases I and II. These data give rise to a model in which Nup98 aids in direction of RNAs to the nuclear pore and provide the first potential mechanism for the role of a mobile nucleoporin.