Proteomic analysis of interchromatin granule clusters
Proteomic analysis of interchromatin granule clusters
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DOI：
10.1091/mbc.e04-03-0253
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发表时间：
2004-08-01
影响因子：
3.3
通讯作者：
Spector, DL
中科院分区：
文献类型：
--
作者：
Saitoh, N;Spahr, CS;Spector, DL
多种参与基因表达的蛋白质以斑点分布定位于哺乳动物细胞核内，主要对应于染色质间颗粒簇（IGC）。我们应用质谱策略来鉴定从小鼠肝核中纯化的这种核细胞器的蛋白质组成。使用这种方法，我们鉴定了 146 种蛋白质，其中许多已被证明定位于 IGC，或者它们的功能与其他已鉴定的 IGC 蛋白质相同。此外，我们还鉴定了 32 种仅可获得序列信息的蛋白质，因此它们代表了新的 IGC 蛋白质候选物。我们发现 54% 的已鉴定 IGC 蛋白在前 mRNA 剪接中具有已知功能。与参与前 mRNA 加工其他步骤的蛋白质相结合，81% 已鉴定的 IGC 蛋白质与 RNA 代谢相关。此外，IGC 组分中还鉴定出了参与转录以及其他几种细胞功能的蛋白质。然而，前 mRNA 加工因子的优势支持了 IGC 作为参与前 mRNA 加工的蛋白质的组装、修饰和/或存储位点的作用。
A variety of proteins involved in gene expression have been localized within mammalian cell nuclei in a speckled distribution that predominantly corresponds to interchromatin granule clusters (IGCs). We have applied a mass spectrometry strategy to identify the protein composition of this nuclear organelle purified from mouse liver nuclei. Using this approach, we have identified 146 proteins, many of which had already been shown to be localized to IGCs, or their functions are common to other already identified IGC proteins. In addition, we identified 32 proteins for which only sequence information is available and thus these represent novel IGC protein candidates. We find that 54% of the identified IGC proteins have known functions in pre-mRNA splicing. In combination with proteins involved in other steps of pre-mRNA processing, 81% of the identified IGC proteins are associated with RNA metabolism. In addition, proteins involved in transcription, as well as several other cellular functions, have been identified in the IGC fraction. However, the predominance of pre-mRNA processing factors supports the proposed role of IGCs as assembly, modification, and/or storage sites for proteins involved in pre-mRNA processing.