《分子生物学》课程PPT教学课件（讲义）lect3 RNA PoSttranscriptional Procession 转录后加工

RNA PoSttranscriptional Procession 转录后加工

RNA Posttranscriptional Procession 转录后加工

Classes of rna Pre-RNA, EARNA: The primary transcript has the same organization as the gene hnrNA, heterogeneous nuclear RNA,核内不均一RNA: Eucaryotic RNa Pol Ii transcribes a variety of different genes SnRNA, small nuclear rna,核内小RNA: is any one of many small RNA species confined to the nucleus: several of the snrNas are involved in splicing or other rna processing reactions SCRNA, small cytoplasmic rna,胞内小RNA: several molecules present in the cytoplasm and(sometimes ) nucleus ·rRNA, ribosomal rna,核糖体RNA: Serve as components of ribosomes tRNA: transfer RNA, #ERNA: carrying an amino acid; the covalent linkage is between the nh2 group of the amino acid and either the 3-or 2-oh group of the terminal base of the trNA mRNA, messager RNA, ERNA: carries genetic message from the chromosome to the ribosomes

Classes of RNA • Pre-RNA, 前体RNA: The primary transcript has the same organization as the gene • hnRNA, heterogeneous nuclear RNA, 核内不均一RNA: Eucaryotic RNA Pol II transcribes a variety of different genes • snRNA, small nuclear RNA, 核内小RNA: is any one of many small RNA species confined to the nucleus; several of the snRNAs are involved in splicing or other RNA processing reactions • scRNA, small cytoplasmic RNA, 胞内小RNA: several molecules present in the cytoplasm and (sometimes) nucleus • rRNA, ribosomal RNA, 核糖体RNA: Serve as components of ribosomes • tRNA: transfer RNA, 转移RNA: carrying an amino acid; the covalent linkage is between the NH2 group of the amino acid and either the 3´- or 2´-OH group of the terminal base of the tRNA t • mRNA, messager RNA, 信使RNA: carries genetic message from the chromosome to the ribosomes

Function of rna Class Function Position hnRNa 成熟mRNA的前体 核内 SRNA 参与 hnRNA的剪接、转运 核内 SCRNA 蛋白质内质网定位合成的信胞内 号识别体的组成成分 rRNA 核蛋白体组成成分 trNa 转运氨基酸 mRNA 蛋白质合成模板

Function of RNA Class Function Position hnRNA 成熟mRNA的前体 核内 snRNA 参与hnRNA的剪接、转运 核内 scRNA 蛋白质内质网定位合成的信 号识别体的组成成分 胞内 rRNA 核蛋白体组成成分 tRNA 转运氨基酸 mRNA 蛋白质合成模板

Types of RNa processing A) Cutting and trimming to generate ends rRNA, tRNa and mrNA B)Covalent modification Add a cap and a poly a tail to mRNA Add a methyl group to 2 -oh of ribose in mRNA and rrNA Extensive changes of bases in trNa C) Splicing pre-rRnA, pre-mRNA, pre-trna by different mechanisms

Types of RNA processing • A) Cutting and trimming to generate ends: – rRNA, tRNA and mRNA • B) Covalent modification: – Add a cap and a polyA tail to mRNA – Add a methyl group to 2’-OH of ribose in mRNA and rRNA – Extensive changes of bases in tRNA • C) Splicing – pre-rRNA, pre-mRNA, pre-tRNA by different mechanisms

The long and winding START RNA TRANSCRIPTION POSSIBLE RNA road ATTENUATION transcript CAPPING aborts SPLICING AND nonfunctional 3′- END CLEAVAGE mRNA sequences POSSIBLE RNA EDITING retention and NUCLEAR EXPORT degradation in nucleus SPATIAL LOCALIZATION IN CYTOPLASM START translation TRANSLATION blocked POSSIBLE TRANSLATIONAL RECODING POSSIBLE RNA RNA degraded STABILIZATION CONTINUED PROTEIN SYNTHESIS Figure 7-87. Molecular biology of the cell, 4th edition

The Long and Winding Road…

Eukaryotic and prokaryotic mrNAs Have major differences-I procaryotic mRNA coding noncoding sequence sequence ⊙PP protein a proteinβ proteinγ eucaryotic mRNA coding noncoding sequence sequence 团 5′ AAAAA150-250 3 5 (A) protein Figure 6-22 part 1 of 2. Molecular Biology of the Cell, 4th Edition

Eukaryotic and Prokaryotic mRNAs Have Major Differences - I

Eukaryotic and prokaryotic MrNAs Have maior differences -ll 5′ end of 7-methylguanosine primary transcript HO OH c!H2⊙CH2 OF 5′-to-5′ (B) triphosphate bridg CH H OH Figure 6-22 part 2 of 2. Molecular Biology of the Cell, 4th Edition

Eukaryotic and Prokaryotic mRNAs Have Major Differences - II

Ribosome核糖体 原核生物核糖体 真核生物核糖体 70sM27×10° 80sM4.2x10 A supramolecular complex of rRNAS and proteins, the BOS site of protein synthesis Have two subunit In eukaryotes binding in M.18×105 M28×10° RER: in prokaryotes SSTRNA 5S TRNA 28S RNA 28S TRNA 5.88 tRNA binding in mRNA 6种蛋白质 19种蛋白质 M.0.9×10° M.1.4×10 16S rRNA 18SrRNA 21种蛋白质 3种蛋白质

Ribosome核糖体 • A supramolecular complex of rRNAs and proteins, the site of protein synthesis • Have two subunit • In eukaryotes, binding in RER; in prokaryotes, binding in mRNA

rrna processing in prokaryotes Seven different operons for rRNA rrn dispersed bought out the genome Each operons transcript a 30S( 6000bp) primary transcript Each primary transcript contains one copy of 5s, 16S and 23S rRNA, together with some tRNA sequence Rnase lll is involved in rRNa processing

一、rRNA processing in prokaryotes • Seven different operons for rRNA rrn dispersed thought out the genome • Each operons transcript a 30S(~6000bp) primary transcript • Each primary transcript contains one copy of 5S,16S and 23S rRNA, together with some tRNA sequence • Rnase III is involved in rRNA processing

Rnase in e coli E.cli中含有的小分子核酸酶 酶 基因 底物 功能 RNasep A tRNA5′端 内切 Rnase rnpB RnaseBN tRNA3′端 外切 Rnase rnd tRNA3′端 外切 Rnase tRNA3′CCA外切 Rnaselll rRNA和mRNA 内切 Naser rRNA和mRNA外切 Rnase rne 5s rrNA 内切 Rnase I n 大部分RNA 内切 RnaseⅡ b RNA 外切 多核苷酸磷酸化酶pp RNA 外切 Rnaseh rn h RNA-DNA杂合链内切

Rnase in E.coli • E.coli中含有的小分子核酸酶 酶 基因 底物 功能 RNaseP rnpA tRNA 5′端 内切 RnaseO rnpB RnaseBN ? tRNA 3′端 外切 RnaseD rnd tRNA 3′端 外切 RnaseT ? tRNA 3′CCA 外切 RnaseⅢ rnc rRNA和mRNA 内切 RnaseR ? rRNA和mRNA 外切 RnaseE rne 5S rRNA 内切 RnaseⅠ rna 大部分RNA 内切 RnaseⅡ rnb RNA 外切 多核苷酸磷酸化酶 pnp RNA 外切 RnaseH rnh RNA-DNA杂合链 内切