A subset of human 35S U5 proteins, including Prp19, function prior to catalytic step 1 of splicing
A subset of human 35S U5 proteins, including Prp19, function prior to catalytic step 1 of splicing
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DOI：
10.1038/sj.emboj.7600241
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发表时间：
2004-06-16
期刊：
影响因子：
11.4
通讯作者：
Lührmann, R
中科院分区：
文献类型：
--
作者：
Makarova, OV;Makarov, EM;Lührmann, R
在剪接体的催化活化过程中，snRNP重塑事件发生，导致35 S US snRNP的形成，该35 S US snRNP含有20 S US snRNP中未发现的大量蛋白质，包括Prp 19和CDC 5。为了研究35 S US蛋白的功能，我们免疫亲和纯化了尚未经历催化活化的人剪接体（命名为BDeltaU 1），其中含有U2，U4，US和U6，但缺乏U1 snRNA。BDeltaU 1和活化的B* 剪接体的蛋白质组成的比较显示，而U4/U6 snRNP蛋白与BDeltaU 1剪接体稳定相关，35 S U 5相关蛋白（存在于B* 中）基本上不存在，这表明它们与复合物B的形成有关。事实上，免疫耗竭/互补实验证明，在剪接的催化步骤I之前需要包括Prp 19的35 S US蛋白的子集，其形成稳定的异聚体复合物，但不需要U4/U6.U5 tri-snRNP的稳定整合。因此，剪接体复合物在特定阶段的蛋白质组的比较可以提供关于哪些蛋白质在剪接的特定步骤中作为一个组起作用的信息。
During catalytic activation of the spliceosome, snRNP remodeling events occur, leading to the formation of a 35S US snRNP that contains a large group of proteins, including Prp19 and CDC5, not found in 20S US snRNPs. To investigate the function of 35S US proteins, we immunoaffinity purified human spliceosomes that had not yet undergone catalytic activation (designated BDeltaU1), which contained U2, U4, US, and U6, but lacked U1 snRNA. Comparison of the protein compositions of BDeltaU1 and activated B* spliceosomes revealed that, whereas U4/U6 snRNP proteins are stably associated with BDeltaU1 spliceosomes, 35S U5-associated proteins (which are present in B*) are largely absent, suggesting that they are dispensable for complex B formation. Indeed, immunodepletion/ complementation experiments demonstrated that a subset of 35S US proteins including Prp19, which form a stable heteromeric complex, are required prior to catalytic step I of splicing, but not for stable integration of U4/U6.U5 tri-snRNPs. Thus, comparison of the proteomes of spliceosomal complexes at defined stages can provide information as to which proteins function as a group at a particular step of splicing.