Tazi J, Alibert C, Temsamani J, Reveillaud I, Cathala G, Brunel C, Jeanteur P
Cell. 1986 Dec 5;47(5):755-66. doi: 10.1016/0092-8674(86)90518-0.
Using a protein blotting method for the detection of nucleic acid binding proteins, we have identified in HeLa cell nuclear extracts an intron binding protein (IBP) that selectively recognizes the 3' splice site region of mammalian pre-mRNAs. The binding site was accurately delineated using oligonucleotides complementary to human beta-globin pre-mRNA. It spans the 3' splice site AG dinucleotide and the crucial polypyrimidine stretch upstream, but includes neither the branchpoint nor the lariat structure. Although the technique used here shows that the binding specificity is an intrinsic property of IBP and does not depend on snRNA-pre-mRNA interactions, it comigrates with U5 snRNP and is immunoprecipitated by anti-Sm antibody. This strongly suggests that IBP belongs to U5 snRNP. We propose that it is involved in one of the earliest steps of the splicing reaction by mediating the interaction of U5 snRNP with the 3' splice site.
我们采用蛋白质印迹法检测核酸结合蛋白，在HeLa细胞核提取物中鉴定出一种内含子结合蛋白（IBP），它能选择性识别哺乳动物前体mRNA的3'剪接位点区域。使用与人β-珠蛋白前体mRNA互补的寡核苷酸精确描绘了结合位点。它跨越3'剪接位点AG二核苷酸和上游关键的多嘧啶序列，但既不包括分支点也不包括套索结构。尽管此处使用的技术表明结合特异性是IBP的固有特性，不依赖于snRNA与前体mRNA的相互作用，但它与U5 snRNP共迁移，并被抗Sm抗体免疫沉淀。这强烈表明IBP属于U5 snRNP。我们认为它通过介导U5 snRNP与3'剪接位点的相互作用，参与剪接反应的最早步骤之一。
