EFFECT OF MUTATIONS AT THE LARIAT BRANCH ACCEPTOR SITE ON BETA-GLOBIN PRE-MESSENGER-RNA SPLICING INVITRO
EFFECT OF MUTATIONS AT THE LARIAT BRANCH ACCEPTOR SITE ON BETA-GLOBIN PRE-MESSENGER-RNA SPLICING INVITRO
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DOI：
10.1038/324589a0
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发表时间：
1986-12-11
期刊：
影响因子：
64.8
通讯作者：
WEISSMANN, C
中科院分区：
文献类型：
--
作者：
HORNIG, H;AEBI, M;WEISSMANN, C
内含子从真核基因的全长转录物（前信使RNA）中以两个步骤切除1，2。首先，前体mRNA在5′剪接位点被切割，并形成分支（lactone）中间体1 -6。然后，在3′剪接位点处的切割和两个外显子的连接导致lxl内含子的释放。接受5′端形成内含子分支的内含子序列在酵母中严格保守7 -9，但在真核细胞中显示出更多的变异10，11。为了进一步研究真核生物分支形成的条件，我们研究了兔珠蛋白基因内含子与正常分支接受腺苷核苷酸突变的体外剪接。我们的结论是，所有四个核苷酸可以作为分支受体，但A和C是首选的G和U在ltubes形成。正常A突变为G或U可导致使用正常分支位点上游一个核苷酸处的A残基。只有到A或C的分支有效地参与第二剪接步骤。
Introns are excised from full-length transcripts (pre-messenger RNAs) of eukaryotic genes in two steps1,2. First, the pre-mRNA is cleaved at the 5′ splice site and a branched (lariat) intermediate is formed1–6. Then, cleavage at the 3′ splice site and ligation of the two exons leads to the release of the lariat intron. The intron sequence which accepts the 5′ end to form the lariat branch is strictly conserved in yeast7–9, but shows more variation in eukary-otes10,11. To investigate the requirements for branch formation in eukaryotes further, we have studiedin vitrosplicing of a rabbit globin gene intron with mutations of the normal branch-accepting adenosine nucleotide. We conclude that all four nucleotides can serve as branch acceptors, but that A and C are preferred to G and U in lariat formation. Mutation of the normal A to G or U can lead to an A residue one nucleotide upstream of the normal branch site being used instead. Only branches to A or C participate efficiently in the second splicing step.