A MAMMALIAN ACTIVITY REQUIRED FOR THE 2ND STEP OF PREMESSENGER RNA SPLICING
A MAMMALIAN ACTIVITY REQUIRED FOR THE 2ND STEP OF PREMESSENGER RNA SPLICING
复制标题
DOI：
10.1074/jbc.270.22.13415
复制
发表时间：
1995-06-02
影响因子：
4.8
通讯作者：
GARCIABLANCO, MA
中科院分区：
文献类型：
--
作者：
LINDSEY, LA;CROW, AJ;GARCIABLANCO, MA
前体剪接成信使RNA通过两步机制发生。在第一步中，5 '-外显子伴随着lactinase中间体的产生而释放，并且在第二步中，外显子连接，以lactinase产物的形式释放内含子。已经证明酿酒酵母的几种基因产物是第二步所专门需要的。虽然哺乳动物蛋白质参与了剪接的第二步，但没有一种蛋白质仅在这一步起作用。我们在这里确定的第一个哺乳动物的活动表明，专门需要的第二步。该活性显示出该剪接步骤的速率增加了5倍，而它对第一步的速率没有影响。该活性不受微球菌核酸酶处理的影响，而它对加热至55 ℃敏感，这表明它不依赖于RNA，但更可能是蛋白质。将第二步活性与第一步所需的其他因子和PSF分离，PSF是一种被认为具有第二步活性的剪接因子。该活性不需要ATP水解，这表明它在剪接的第二步的后期阶段起作用。
Splicing of precursors to messenger RNAs occurs via a two-step mechanism. In the first step, the 5'-exon is released concomitant with the production of a lariat intermediate, and in the second step, the exons are joined, releasing the intron in the form of a lariat product. Several gene products of the yeast Saccharomyces cerevisiae have been shown to be required exclusively for the second step. Although mammalian proteins have been implicated in the second step of splicing, none have been shown to act only at this step. We identify here the first mammalian activity shown to be exclusively required far the second step. The activity was shown to increase by 5-fold the rate for this splicing step, whereas it had no effect on the rate of the first step. The activity was not affected by treatment with micrococcal nuclease, whereas it is sensitive to heating to 55 degrees C, suggesting that it is not dependent on an RNA, but more likely is a protein. The second step activity was separated from other factors required for the first step and from PSF, a splicing factor thought to have a second step activity. The activity does not require ATP hydrolysis, suggesting that it acts at a late stage of the second step of splicing.