相关实验视频
Updated: Jul 19, 2026
09:16
Eukaryotic Polyribosome Profile Analysis
Published on: June 15, 2010
概括
来自像reovirus和VSV这样的病毒的信使RNA (mRNA) 获得了特定的5'帽结构,m-7-G. 这种甲基化帽子对于刺激无细胞系统中的蛋白质合成至关重要.
科学领域:
- 分子生物学分子生物学
- 病毒学 病毒学
- 生物化学 生物化学
背景情况:
- 传递 RNA (mRNA) 在蛋白质合成中起着至关重要的作用.
- mRNA的5端结构可以影响其翻译效率.
- 在病毒和细胞mRNA中观察到特定的修改,如甲基化.
研究的目的:
- 为了调查reovirus和VSVmRNAs的特定甲基化.
- 确定5端m-7-G结构在mRNA翻译中的作用.
- 分析脱帽对蛋白质合成的影响.
主要方法:
- 用小麦胚芽和小鼠L细胞的蛋白质合成提取物进行非甲基化reovirus和VSVmRNA的酶性甲基化.
- 五端盖结构的表征为m-7-G(5 ') p p p p ((5 ') N.
- 在体外蛋白质合成测试中使用甲基化和脱盖的mRNAs.
- 贝塔消除反应以去除5-终端m-7-G盖.
主要成果:
- 没有甲基化的reovirus和VSVmRNA被特别甲基化,形成m-7-G(5 ') p p p p p ((5 ') N帽结构.
- 还发现网细胞mRNA含有5-终端m-7-G帽.
- 具有5端m-7-G盖的MRNA在体外显著刺激了蛋白质合成.
- 通过β消除去除m-7-G盖的移除取消了mRNA翻译.
结论:
- 五端的m-7-G帽结构是专门添加到病毒mRNAs.
- 这种甲基化盖对于从这些mRNA中启动蛋白质合成至关重要.
- 该m-7-G帽作为mRNA翻译的关键调节元素.
相关概念视频
02:36Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
02:33Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
02:28Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
01:35Pre-mRNA Processing: Modification of pre-mRNA Ends
In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA to distinguish it from mature mRNA.
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...
02:36Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
02:33Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...