Schmelzer C, Schweyen R J
Cell. 1986 Aug 15;46(4):557-65. doi: 10.1016/0092-8674(86)90881-0.
Group II intron bl1 from yeast mitochondria can undergo self-splicing in vitro. Exons become correctly ligated, and the excised intron has a lariat structure similar to that of introns from nuclear mRNA. The branch point of the bl1 lariat is located eight or nine nucleotides upstream of the 3' end of the intron and is part of a hairpin structure that is well conserved among group II introns. Several mutations next to the branch point and in other parts of the core structure of group II introns are shown to affect lariat formation. One of them, carried by strain M4873, abolishes splicing in vivo and in vitro, apparently by changing the architecture of the hairpin structure containing the branch point. Similarities between group II introns and nuclear pre-mRNA introns are discussed in terms of evolutionary relatedness.
来自酵母线粒体的II组内含子bl1可在体外进行自我剪接。外显子能正确连接，切除的内含子具有与核mRNA内含子类似的套索结构。bl1套索的分支点位于内含子3'端上游八或九个核苷酸处，是II组内含子中高度保守的发夹结构的一部分。II组内含子核心结构中分支点附近及其他部位的几个突变显示会影响套索的形成。其中一个由M4873菌株携带，在体内和体外均消除了剪接，显然是通过改变包含分支点的发夹结构的构象。从进化相关性方面讨论了II组内含子与核前体mRNA内含子之间的相似性。
