PROCESSING OF PREMESSENGER RNA

脊椎动物的基因通常分为许多小的外显子 被相当大的内含子分开。这一建议旨在 研究外显子被识别和组装的机制 进入活动剪接体，以便正确地协调组成性剪接体， 和差异剪接。这项提议所依据的假设 外显子是脊椎动物中剪接位点识别的单位（在 与S.酿酒酵母）在一个过程中，我们有 称为外显子定义。在下一阶段，我们计划继续 研究剪接位点外显子视角的优点 识别.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 外显子序列对于外显子定义是最佳。待测试的假设 外显子强度是这些元素的组合， 组成型外显子维持所有三个外显子的最小平衡， 识别;和替代外显子将是次优的一个或 更多的是为了监管。我们特别感兴趣的是 外显子内部的某些序列促进或 抑制他们的认知。 2.组成型长外显子是如何识别的？脊椎动物基因外显子 很少超过300个核苷酸，我们发表的工作表明，外显子 定义在此范围内具有操作限制。偶尔出现长外显子， 然而，它是存在。我们将问他们是如何被认可的。 3.组成型迷你外显子是如何识别的？一些脊椎动物的外显子 非常小（12个核苷酸以下）。外显子定义表明， 外显子的两端同时被识别，这是一个有问题的问题。 对于这样短的外显子。我们将探讨如何识别迷你外显子。 4.外显子定义的分子机制是什么？以获取 了解外显子定义如何运作，我们将确定 外显子定义复合体的组成。我们还将调查 ATP在外显子定义中的作用？ 5.我们能否建立一个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 外显子定义为阴性的提取物，我们可以向其添加分数 恢复外显子的定义。该补充系统将用于 解读个体因素的作用。

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.