PROTEIN/RNA INTERACTIONS IN SPLICE SITE SELECTION

描述（由申请人提供）：大多数人类基因被称为内含子的非编码序列中断。新生的转录物必须被加工以去除内含子并将编码序列连接成连续的成熟mRNA分子。人类基因组计划提供了一个估计，大约3 × 10/9碱基对（bp）的基因组中只有1 - 1.5%是由编码序列或外显子跨越的，而内含子占基因组的大约24%。显然，细胞机器面临着一项艰巨的任务，即精确定位基因转录本内的剪接位点。当某些外显子序列被跳过或包含时，复杂性的另一个维度被添加，这种现象被称为选择性剪接。选择性剪接广泛存在于人类基因中，在发育和分化过程中对基因表达起着重要的调控作用。选择性剪接也负责在某些细胞（如神经元）中产生分子多样性。 前体mRNA的剪接涉及组分的有序组装，包括小的核核糖核蛋白颗粒（snRNP）和额外的蛋白质剪接因子，导致形成大的50- 60 S复合物，称为剪接体。我们有兴趣从结构的角度来理解剪接位点识别的分子机制。在这个建议中，我们集中我们的研究几个很好的特点是人类剪接因子，剪接位点选择，即SR蛋白，异质核核糖核蛋白A1（hnRNP A1）和U2辅助因子（U2 AF）是重要的。

DESCRIPTION (provided by applicant): Most human genes are interrupted by non-coding sequences known as introns. The nascent transcript must be processed to remove the introns and to join the coding sequence into a contiguous mature mRNA molecule. The human genome project provided an estimate that only 1 to 1.5% of the approximately 3x10/9 base pair (bp) genome is spanned by coding sequences or exons, whereas introns occupy approximately 24% of the genome. It is apparent that the cellular machinery is presented with a formidable task to precisely locate the splice sites within a gene's transcript. Another dimension of complexity is added when certain exon sequences are skipped or included, a phenomenon known as alternative splicing. Alternative splicing occurs in a large number of human genes and it plays important roles in regulating gene expression during development and differentiation. Alternative splicing is also responsible for generating molecular diversity in certain cells, such as neurons. Splicing of pre-mRNA involves an ordered assembly of components, including small nuclear ribonucleoprotein particles (snRNP) and additional protein splicing factors, resulting in the formation of a large 50-60S complex, termed the spliceosome. We are interested in understanding the molecular mechanism of splice site recognition from a structural standpoint. In this proposal, we focus our study on several well characterized human splicing factors that are important for splice site selection, namely, SR proteins, heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) and the U2 auxiliary factor (U2AF).