An upstream AG determines whether a downstream AG is selected during catalytic step II of splicing
An upstream AG determines whether a downstream AG is selected during catalytic step II of splicing
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DOI：
10.1128/mcb.21.5.1509-1514.2001
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发表时间：
2001-03-01
影响因子：
5.3
通讯作者：
Reed, R
中科院分区：
文献类型：
--
作者：
Chua, K;Reed, R
必须存在特定的机制来确保选择在剪接的第二个酯交换步骤期间充当 3' 剪接位点的 AG 二核苷酸的保真度。在这里，我们表明该 AG 的最佳位置是在分支点序列 (BPS) 下游的狭窄距离内（19 至 23 个核苷酸 [nt]）。与之前的预期相反，即使在酯交换反应中使用位于更佳下游的第二个 AG 时，距 BPS 小于 23 nt 的 AG 也始终能够被识别。事实上，最接近 BPS 的 AG 实际上决定了参与反应的 AG 的精确位置。这种机制通过一般定位步骤和精确定位步骤来识别 AG，可用于实现保真度，同时允许 3' 剪接位点位置的灵活性。
Specific mechanisms must exist to ensure fidelity in selecting the AG dinucleotide that functions as the 3' splice site during the second transesterification step of splicing. Here we show that the optimal location for this AG is within a narrow distance (19 to 23 nucleotides [nt]) downstream from the branch point sequence (BPS). Contrary to previous expectations, AGs located less than 23 nt from the BPS are always recognized, even when a second AG located more optimally downstream is used in the transesterification reaction. Indeed, the AG closest to the BPS actually dictates the precise location of the AG that engages in the reaction. This mechanism, in which the AG is identified by a general localization step followed by a precise localization step, may be used to achieve fidelity while allowing flexibility in the location of 3' splice sites.