PROCESSING OF PREMESSENGER RNA

脊椎动物的基因通常被分成许多小的外显子 被相当大的内含子隔开。这项建议的目的是 研究外显子被识别和组装的机制 到活性剪接体中，以便正确地编排构成体 和差异剪接。这项提议所依据的假设 外显子是脊椎动物剪接位点识别的单位(in 与酿酒酵母中的内含子形成对比) 称为外显子定义。在接下来的一段时间里，我们计划继续 探讨剪接位点外显子视角的优点 承认。将提出五个问题： 1.哪些顺式作用序列决定了外显子定义的效率？ 我们将询问剪接位点强度、外显子长度和 外显子序列是定义外显子的最佳序列。需要检验的假设 外显子强度是这些元素的组合， 构成外显子维持所有三个外显子的最小平衡 可供选择的外显子对于一个或多个外显子来说将是次优的 更多的是为了允许监管。我们对调查特别感兴趣 外显子内部的某些序列可能促进或 抑制他们的识别。 2.如何识别构成性长外显子？脊椎动物基因中的外显子 很少超过300个核苷酸，我们发表的研究表明外显子 清晰度在此范围内具有操作限制。偶尔会有长外显子， 然而，存在。我们会问他们是如何被识别的。 3.如何识别构成的微型外显子？一些脊椎动物的外显子是 极小的(不到12个核苷酸)。外显子定义表明 外显子的两端同时被识别，这是一个问题 如此短的外显子的情况。我们将询问迷你外显子是如何识别的。 4.外显子定义的分子机制是什么？为了获得一份 理解外显子定义是如何运作的，我们将确定 外显子定义复合体的组成。我们还将调查 三磷酸腺苷在外显子定义中的作用？ 5.能否建立外显子定义因子的互补系统？ 为了研究外显子定义所需的因素，我们希望建立一个 提取外显子定义为阴性的片段，我们可以向其添加分数 恢复外显子定义。这一互补体系将被用于 解读个人因素的作用。

Vertebrate genes are typically split into a number of small exons separated by considerably larger introns. This proposal is aimed at investigating the mechanism whereby exons are recognized and assembled into the active spliceosome so as to correctly orchestrate constitutive and differential splicing. The hypothesis upon which this proposal rests is that the exon is the unit of splice site recognition in vertebrates (in contrast to the intron in S. cerevisiae) in a process that we have referred to as exon definition. During the next period we plan to continue to investigate the merits of an exon perspective of splice site recognition. Five questions will be posed: 1. What cis-acting sequences determine the efficiency of exon definition? We will ask what combination of splice site strength, exon length, and exon sequence are optimal for exon definition. The hypothesis to be tested is that exon strength is a combination of these elements, and that constitutive exons maintain a minimal balance of all three for recognition; and that alternative exons will be sub-optimal for one or more to permit regulation. We are especially interested in investigating the possibility that certain sequences internal to exons promote or inhibit their recognition. 2. How are constitutive long exons recognized? Exons in vertebrate genes rarely exceed 300 nucleotides and our published work suggests that exon definition has operational limits in this range. Occasional long exons, however, exist. We will ask how they are recognized. 3. How are constitutive mini-exons recognized? Some vertebrate exons are exceedingly small (under 12 nucleotides). Exon definition suggests that both ends off an exon are simultaneously recognized, a problematic situation for such short exons. We will ask how mini-exons are recognized. 4. What is the molecular mechanism of exon definition? To gain an understanding of how exon definition operates we will determine the composition of the exon definition complex. We will also investigate the role of ATP in exon definition? 5. Can we establish a complementation system for exon definition factors? To study the factors required for exon definition, we wish to establish an extract that is negative for exon definition to which we can add fractions that restore exon definition. This complementation system will be used to decipher the role of individual factors.