在酵母酵母中,tRNA在核和细胞质之间积极穿
Akira Takano1, Toshiya Endo, Tohru Yoshihisa
1Department of Chemistry, Graduate School of Science, Japan Science and Technology Corporation, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
概括
转移RNAs (tRNAs) 之前被认为只能离开核一次. 新的酵母研究表明tRNA可以重新进入细胞核,这表明它们在细胞区之间穿.
科学领域:
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
- 酵母遗传学 酵母遗传学
背景情况:
- 转移RNAs (tRNAs) 是蛋白质合成的重要分子.
- 以前,人们认为tRNAs只有在成熟后才能从核转移到细胞质中.
研究的目的:
- 为了研究成熟的tRNAs在酵母中穿过核外的运动.
- 为了确定tRNA是否表现出核与细胞核之间的双向传输.
主要方法:
- 对酵母出口突变菌在核中积累成熟的tRNA的分析.
- 评估Ran循环在tRNA核进口中的能源依赖性和参与.
主要成果:
- 观察到成熟的tRNAs在特定酵母出口突变的核中积累.
- 这种核积累甚至发生在没有活跃转录的情况下.
- 观察到的进口过程依赖能源,但独立于Ran循环.
结论:
- 转移RNAs (tRNAs) 在酵母菌中的细胞核和细胞质之间积极穿.
- 这一发现挑战了以前的单向tRNA出口模型.
相关概念视频
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...
tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
Regulated mRNA Transport
In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...
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...
tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
Regulated mRNA Transport
In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...


