tRNAは,酵母菌の核とサイトゾールの間を活発にシャトルします
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.
Science (New York, N.Y.)
|May 21, 2005
まとめ
トランスファーRNA (tRNA) は以前は,核を1回だけ退去すると考えられていた. 酵母菌における新しい研究は,tRNAが細胞核に再び侵入し,細胞間をシャトルで移動することを示しています.
科学分野:
- 分子生物学は分子生物学である.
- 細胞生物学 細胞生物学
- イースト遺伝学 イースト遺伝学
背景:
- 転送RNA (tRNA) は,タンパク質合成に不可欠な分子である.
- 以前は,tRNAは成熟後に核から細胞溶液に移動するだけだと理解されていました.
研究 の 目的:
- 酵母における核包膜の横断で成熟したtRNAの移動を調査する.
- tRNAが核とサイトゾール間の双方向輸送を示すかどうかを判断する.
主な方法:
- 酵母出口変異菌が成熟したtRNAを核に蓄積する分析.
- tRNA核インポートにおけるRanサイクルのエネルギー依存性と関与を評価する.
主要な成果:
- 成熟したtRNAは,特定の酵母輸出変異体の核内に蓄積することが観察されました.
- この核の蓄積は,活発な転写なしでも発生しました.
- 観測された輸入プロセスはエネルギーに依存しているが,Ranサイクルとは独立していた.
結論:
- 移転RNA (tRNA) は,酵母菌の核と細胞溶液の間に活発に移動する.
- この発見は,一方向的なtRNA輸出の以前のモデルに異議を唱える.
関連する概念動画
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...
02:26tRNA 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...
02:22Regulated 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...
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...
02:26tRNA 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...
02:22Regulated 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...