分子生物学(杨洋)第六章rna剪接-rnasplicing

1、杨洋教授welcome to my molecular biology class，Huazhong university of science and technology，ch 12: mechanisms of transcription ch 1:确保exconson连接不减去或增加核苷酸Alternative splicing : some pre-mrnas can be spliced in more than one way。gene rating alternative mrnas . 60% of the human genes are spliced in this ma

2、nner。一些以前的mrna具有多种茄子拼接方法，可生成不同的mRNA。以这种方式，一个基因可以产生多个多肽产物。通过可变剪接从一个基因中获得的多种产物的数量可以从2种到数百种甚至数千种。Outline，RNA连接的化学基本分割过程包括自身分割RNA剪辑mRNA传输，TOPIC 1 : the Chemistry of RNA Splicing(RNA分割的化学基础)，1.1 sequences within the RNA)The borders between introns and exons are marked by specific nucle otide sequences wi

3、thin The pre-mRNAs内含子和外显子边界显示为pre-mrna内的特殊核苷酸序列。牙齿序列表示需要切割的地方，即Figure 13-2，在内含子和外显子边界的核苷酸序列，5分割网站，3分割网站，分叉等。5分割网站(5分割网站): the exon-intron boundary at the 5 end of the intron 3 5 splice site(5 3分割网站): the exon-intron boundary at the 3 ee1 . 2 the intron is removed in a form called a lariat(套索)as the

4、Flanking Exons are joined s flysing(two successive transesterification(two successive transesterification)step 13360 The oh of The conserved a at The branch site attacks The phosphor yl group of The conserved gin The 5 splice site . as a result，The 5 exon is、figure 13-3、three-way结果5和3外弦连接起来，将内含子释放到出

5、发端，新释放的内含子的形状像套索(lariat)。step 23360 The oh The 5 exon attacks The phosphor yl group at The 3 splice site . as a consequence，The 5 and 3 exons are joined and The intron is libenceTrans-splicing:最初位于两个不同RNA分子中的外弦，连接到相同的mRNA，Figure 13-5，Not a lariat，标准剪接：套索结构反向剪接：Y型分支结构，Topic 2 the Spliat2 . 1 RNA spli

6、cing is carried out by a large complex called splice osome(RNA拼接是由称为剪接的大复合体完成的)The above described splicing of introns from prommany functions of the splice osome are carried out by its RNA components(分离器的大部分功能是由RNA而不是蛋白质完成的)，the five rnas (u1，us 100-300 nas)the complexes of sn RNA And proteins are

7、called small nuclear rie小核心糖蛋白，RNA-蛋白质复合物)the splice osome is the largest sn RNP，And the exact makebringing those sites togg 3。catalyzing(或helping to catalyze)the RNA cleavage催化剂(或催化剂)RNA剪接和连接反应RNA-RNA，RNA-protein and protein-protein Intel牙齿效应将5剪接位点和支点拉在一起。这种相互作用促进了剪接反应，并提供了准确性。一些没有RNA的蛋白质也参与了剪接反应U2

8、AF，识别聚嘧啶区和3剪接位点，并帮助在剪接反应开始阶段将支点结合蛋白(BBP)结合到支点上。BBP将替换为U2 snRNP，杠杆将替换。RNA-RNA interactions between different SNR NPS、and between SNR NPS and pre-mrna、topic 3 splicing pathways(剥离过程)，3.-初始(e)复合体，Assembly step 2:组装第二阶段U2 binds to the branch site，And then a complex is formed . 2 . the base-pairing betwe

9、en the U2 And，在assembly step 2:第二阶段U2AF的帮助下，U2 snRNP将BBP合并到分支点以形成a复合体。U2 snRNA和成对的分叉组合形成双螺旋RNA。由于杠杆中的腺苷酸不配对，所以单碱挤出的腺苷酸不配对，可以与5结部位，Figure 13-8，E Complex，A Complex，Figure 13-6B，Assembly反应。U5和U6 form the tri-sn RNP particle . 2 . with the entry of the tri-sn RNP，the A Complex is converted into the B Complex . A Complex通过了，牙齿三茄子SNRand U6 replaces it at the 5 splice site . U4 is released from the complex，allowing U6 to interact with U2(figure 13-6c)。this as U6与相同的区域配对。U4离开切割体