PATHWAYS FOR SELECTION OF 5' SPLICE SITES BY U1 SNRNPS AND SF2/ASF
PATHWAYS FOR SELECTION OF 5' SPLICE SITES BY U1 SNRNPS AND SF2/ASF
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DOI：
10.1002/j.1460-2075.1993.tb06034.x
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发表时间：
1993-09-01
期刊：
影响因子：
11.4
通讯作者：
KRAINER, AR
中科院分区：
文献类型：
--
作者：
EPERON, IC;IRELAND, DC;KRAINER, AR
我们已经使用了对核糖核酸酶H的保护来研究U1小核核糖核蛋白颗粒（snRNP）决定使用两个可选的5'剪接位点的机制。U1 snRNP与选择性共有剪接位点的初始结合是不加选择的，并且在高比例的前mRNA分子上，两个位点同时被占据。当位点接近时，这抑制了剪接。我们建议，双重占用导致使用的下游位点的剪接，这是邻近效应的原因，看到强选择性剪接位点。该模型预测，任何强度的上游位点的剪接需要U1 snRNP对下游位点的低亲和力。通过切割U1 snRNA的5'端和改变腺病毒E1 A基因下游位点的序列来测试该预测。剪接因子SF 2/ASF对下游5'剪接位点利用的增强似乎是由U1 snRNP不加区别地与所有位点结合的强度的增加介导的。
We have used protection against ribonuclease H to investigate the mechanisms by which U1 small nuclear ribonucleoprotein particles (snRNPs) determine the use of two alternative 5' splice sites. The initial binding of U1 snRNPs to alternative consensus splice sites was indiscriminate, and on a high proportion of pre-mRNA molecules both sites were occupied simultaneously. When the sites were close, this inhibited splicing. We propose that double occupancy leads to the use of the downstream site for splicing and that this is the cause of the proximity effect seen with strong alternative splice sites. This model predicts that splicing to an upstream site of any strength requires a low affinity of U1 snRNPs for the downstream site. This prediction was tested both by cleaving the 5' end of U1 snRNA and by altering the sequence of the downstream site of an adenovirus E1A gene. The enhancement of downstream 5' splice site use by splicing factor SF2/ASF appears to be mediated by an increase in the strength of U1 snRNP binding to all sites indiscriminately.