Subcellular localization of RPB5-mediating protein and its putative functional partner
Subcellular localization of RPB5-mediating protein and its putative functional partner
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DOI：
10.1128/mcb.24.19.8556-8566.2004
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发表时间：
2004-10-01
影响因子：
5.3
通讯作者：
Murakami, S
中科院分区：
文献类型：
--
作者：
Delgermaa, L;Hayashi, N;Murakami, S
我们之前发现了一种新型细胞蛋白，RPB5 介导蛋白 (RMP)，它保留了辅阻遏物活性，并通过乙型肝炎病毒 X 蛋白在功能上拮抗转录调节。使用绿色荧光蛋白融合蛋白形式检查 RMP 的亚细胞定位。我们发现核定位信号（NLS）和作为细胞质定位信号（CLS）的卷曲螺旋（CC）结构域对于RMP的亚细胞定位很重要。 CLS显然起主导作用，因为RMP主要定位在细胞质中，细胞核中信号微弱且弥散，而只有在CLS不存在的情况下，NLS才对RMP的核定位是不可或缺的。使用酵母双杂交方法，我们分离出了一种假定的辅阻遏物，DNA 甲基转移酶 I 相关蛋白 (DMAP1)，它被发现与 RMP 的 CC 结构域结合。 DMAP1 通过与 RMP 的 CC 结构域相互作用，以剂量依赖性方式促进 RMP 的核定位和 RMP 的辅阻遏物活性。这些结果根据最近的一篇论文进行了讨论，该论文显示 URI 在 TOR 信号通路中具有新颖的进化保守作用。
We previously identified a novel cellular protein, RPB5-mediating protein (RMP), that retains corepressor activity and functionally antagonizes transcriptional modulation via hepatitis B virus X protein. The subcellular localization of RMP was examined using green fluorescent protein-fused protein forms. We found that a nuclear localization signal (NLS) and a coiled-coil (CC) domain functioning as a cytoplasmic localization signal (CLS) are important for the subcellular localization of RMP. The CLS apparently acts dominantly, since RMP was mostly localized in the cytoplasm with weak and diffuse signals in the nucleus, and the NLS was indispensable for the nuclear localization of RMP only in the absence of the CLS. Using a yeast two-hybrid method, we isolated a putative corepressor, DNA methyltransferase I-associating protein (DMAP1), which was found to bind to the CC domain of RMP. DMAP1 facilitated the nuclear localization of RMP and the corepressor activity of RMP in a dose-dependent manner by interacting with the CC domain of RMP. These results are discussed in light of a recent paper showing a novel evolutionarily conserved role of URI in the TOR signaling pathway.