Cheng T
Tex Rep Biol Med. 1980;40:87-100.
During the last three years, significant progress has been made in the characterization of the structure of globin RNA precursors and the steps involved in their modifications to mature mRNA. Aside from the coding sequence, IVSs in RNA precursors have a critical function in the formation of mature mRNA. However, certain questions regarding the role IVSs might have in RNA processing still need to be answered. In order to understand normal globin gene expression, it will be important to know whether specific nucleoside sequences or conformational changes in the structure of the RNA due to IVSs are required for each processing enzyme in the stepwise cleavage-ligation reaction. The availability of purified RNA processing intermediates for sequencing should enable us to map the cleavage-ligation sites in each RNA. It will be interesting to determine whether any methylated nucleotides exist in IVSs and whether methylation is involved in the processing pathway. In addition, further evidence should be forthcoming to demonstrate the importance of IVS removal in the transport of RNA from nucleus to cytoplasm. Information obtained from these studies should help us to understand further the post-transcriptional control of the globin gene expression in normal states as well as in states of abnormal globin chain synthesis, such as the thalassemias.
在过去三年中，珠蛋白RNA前体的结构表征及其修饰为成熟mRNA的过程取得了重大进展。除编码序列外，RNA前体中的内含子在成熟mRNA的形成中具有关键作用。然而，关于内含子在RNA加工中可能发挥的作用，仍有一些问题有待解答。为了理解正常的珠蛋白基因表达，了解在逐步的切割-连接反应中，每种加工酶是否需要特定的核苷序列或由于内含子导致的RNA结构构象变化非常重要。纯化的RNA加工中间体用于测序将使我们能够绘制每种RNA中的切割-连接位点。确定内含子中是否存在任何甲基化核苷酸以及甲基化是否参与加工途径将很有趣。此外，应该会有更多证据证明去除内含子在RNA从细胞核运输到细胞质中的重要性。从这些研究中获得的信息应有助于我们进一步了解正常状态以及珠蛋白链合成异常状态（如地中海贫血）下珠蛋白基因表达的转录后调控。
