FUNCTIONS OF SMALL NUCLEOLAR RNAS

核糖体生物发生是细胞生物学中的一个基本过程，但很少 已经知道了它的机制。E_1、E_2和E_3小核仁RNA (SnoRNAs)不属于最知名的snoRNAs类别，因为它们 缺少存在于这些snoRNA中的序列。这三个人 SnoRNAs直接与核糖体RNA的独特片段相互作用 体内的前体(前rRNA)。这三种snoRNA各自的降解 产生独特的青蛙卵母细胞前rRNA加工表型，即 被相应的snoRNA逆转。EL和E2RNAs是 18S rRNA的形成。这些snoRNA中的每一个都具有独特的保守性 序列。基于现有的结果，我们提出了这些结论 SnoRNA：a)至少参与了前rRNA的加工 在前rRNA裂解位点之后，5‘端的E1和3’端的E2 18S rRNA序列，以及5.8S rRNA 5‘端的E3 序列；以及b)具有新颖且可能唯一的顺式作用结构域 RRNA加工可能与新的蛋白质相互作用 功能。长期目标：确定人类免疫缺陷的分子机制 小核仁核糖核蛋白E1、E2和E3的功能 核糖体形成中的颗粒。 我们的具体目标是：1)确定snoRNA顺式作用元件 这些snoRNAs在前rRNA加工中的功能所需，2) 确定这些snoRNA结构域与蛋白质的相互作用，前 RRNA和其他snoRNA，这是功能所需的，3)测试 这些功能的模型集中在这些snoRNA元件和这些 相互作用，以及4)开发无细胞的Pre-rRNA处理系统 依赖于外源EL或E2RNA。这将通过以下方式完成 SnoRNA突变分析、迁移率改变分析、RNA-蛋白质 光交联型反义2‘-0-甲基寡核苷酸 竞争，以及snoRNA和Pre-rRNA补偿突变分析，在 注射青蛙卵母细胞和转基因哺乳动物细胞。E2RNA基因 位于层粘连结合蛋白基因的一个内含子中 在肿瘤侵袭和转移中起重要作用。

Ribosome biogenesis is a fundamental process in cell biology but little is known about its mechanism. E1, E2 and E3 small nucleolar RNAs (snoRNAs) do not belong to the best known class of snoRNAs since they lack the sequences that are present in those snoRNAs. These three snoRNAs interact directly with unique segments of ribosomal RNA precursor (pre-rRNA) in vivo. Degradation of each of these three snoRNAs produces a unique frog oocyte pre-rRNA processing phenotype that is reversed by the corresponding snoRNA. El and E2 RNAs are essential for 18S rRNA formation. Each of these snoRNAs has unique conserved sequences. Based on the available results, we propose that these snoRNAs: a) are at least involved in pre-rRNA processing at the following pre-rRNA cleavage sites, E1 at the 5' end and E2 at the 3' end of the 18S rRNA sequence, and E3 at the 5' end of the 5.8S rRNA sequence; and b) have novel, and probably unique, cis-acting domains for rRNA processing that may interact with novel proteins for their functions. Long-term goal: To determine the molecular mechanisms of the functions of the E1, E2, and E3 small nucleolar ribonucleoprotein particles in ribosome formation. Our Specific Aims are 1) to identify the snoRNA cis-acting elements needed for the functions of these snoRNAs in pre-rRNA processing, 2) to identify the interactions of these snoRNA domains with proteins, pre- rRNA and other snoRNAs, that are required for function, 3) to test the models of these functions focused on these snoRNA elements and these interactions, and 4) to develop cell-free pre-rRNA processing systems that are dependent on exogenous El or E2 RNA. This will be done by snoRNA mutation analysis, mobility shift assay, RNA-protein photocrosslinking , antisense 2'-0-methyloligoribonucleotide competition, and snoRNA and pre-rRNA compensatory mutation analysis, in injected frog oocytes and transfected mammalian cells. The E2 RNA gene lies in an intron of the gene for a lamininbinding protein that is important in tumor invasion and metastasis.