概括
研究人员在Xenopus卵细胞中确定了一种下游元素,该元素对于处理人类U2前体RNA (pre-U2RNA) 至关重要. 这个元素决定了3'端的形成,这表明保留了RNA处理机制.
科学领域:
- 分子生物学分子生物学
- 处理RNA处理RNA处理
- 基因表达 基因表达
背景情况:
- U2小核RNA (snRNA) 对于结合体的功能至关重要.
- 对于snRNAs的3'端形成的精确机制尚未完全理解.
- 之前的研究表明,下游元素在RNA处理中的参与.
研究的目的:
- 研究在Xenopus卵细胞中合成的人类U2前体RNA (pre-U2RNA) 的3'端形成的要求.
- 为了确定负责U2 RNA前处理的特定序列元素.
- 为了比较U2 snRNA的处理机制与其他RNA分子,如基因组 mRNA.
主要方法:
- 在Xenopus卵细胞中微注射人类U2 snRNA基因.
- 使用分子生物学技术分析合成的U2RNA和前体形式.
- 位点定向的突变发生改变侧翼序列并识别功能元素.
- 序列分析以确定保存的图案.
主要成果:
- 奇诺普斯卵细胞产生成熟的U2 snRNA和前体 (U2 之前的RNA) 具有延伸的3'端.
- 在U2 3'-侧翼序列中,位于+16和+37之间的下游元素对于U2 RNA 3'-前端形成至关重要.
- 改变这个元素的距离或周围序列并不能阻止在特定区域内产生3'端.
- U2 snRNA的3'终端干环不需要进行前体处理.
- 在下游元素中确定了一个保存序列模式 (GTTTN0-3AAAPuNNAGA).
结论:
- 在Xenopus卵细胞中,人类前U2RNA的3'端形成取决于特定的下游序列元素.
- 这种处理机制似乎与基因素mRNA 3'末端形成的处理机制不同,但与其相关.
- 保存的序列元素表明,对于RNA聚合酶II转录的3'端处理,有一个共同的监管原则.
相关概念视频
RNA Splicing
Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...
pre-mRNA Processing
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 to it (7-Methyl guanosine). This 5’ cap helps the...
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 to it (7-Methyl guanosine). This 5’ cap helps the...
Ribosomal RNA Synthesis
Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Transfer 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...
Pre-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...
Nucleic Acid Structure
The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose's second carbon and a hydrogen on the deoxyribose's second carbon. The phosphate residue attaches to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms a 5′ to 3′ phosphodiester linkage.
DNA Structure
DNA has a double-helix structure. The...
DNA Structure
DNA has a double-helix structure. The...


