関連する実験動画
Updated: May 20, 2026

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Xenopus laevis as a Model to Identify Translation Impairment
Published on: September 27, 2015
レウシン-tRNAがCUGで起動すると,MHCクラスIによるタンパク質合成とプレゼンテーションのためのコードンが開始されます
Shelley R Starck1, Vivian Jiang, Mariana Pavon-Eternod
1Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
まとめ
細胞は,tRNAベースのユニークなメカニズムを使用して,非正規のスタートコドンからタンパク質合成を開始します. このプロセスは,細胞毒性T細胞による効果的な免疫監視に不可欠な新しいペプチドの生成を可能にします.
科学分野:
- 分子生物学は分子生物学である.
- 免疫学 免疫学とは
- 細胞生物学 細胞生物学
背景:
- 効果的な免疫監視は,MHCクラスI分子を介して新たに合成されたポリペプチドを提示する細胞毒性T細胞に依存しています.
- タンパク質合成は通常,AUGスタートコドンから開始されますが,AUG以外のイニシアチブも,異なる翻訳メカニズムを経由して発生します.
研究 の 目的:
- 非AUGのスタートコドン,特にCUGでの翻訳開始の基礎となる生化学的メカニズムを調査する.
- 移転RNA (tRNA) と非AUG誘発タンパク質合成における誘発因子の役割を決定する.
主な方法:
- リボソーム初期化複合体の生化学分析.
- CUGとAUGのコドンでの翻訳開始の調査.
- 特定のtRNAおよびエウカリオットのイニシアーション因子に対する要求の評価.
主要な成果:
- 細胞は,延長型ルシン結合tRNA (Leu-tRNA) を利用して,暗号的なCUGスタートコドンで翻訳を開始します.
- このCUG/Leu-tRNAのイニシアチブは,正規のAUG/Met-tRNA経路とは独立しています.
- このプロセスは,エウカリオットのイニシアーション因子2A.の表現を必要とします.
結論:
- tRNAベースの翻訳開始メカニズムは,AUGが誘発しないタンパク質合成を可能にします.
- この代替翻訳経路は,MHCクラスIプレゼンテーションのためのペプチドの供給に寄与する.
- この発見は,タンパク質合成とその免疫監視における役割についての理解を広げています.
関連する概念動画
Initiation 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...
Initiation 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...
Leaky 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...
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...
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...
From DNA to Protein
The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of mRNAs, which in turn specify the sequence of amino acids making up all proteins. The decoding of one molecule to another is performed by specific proteins and RNAs. Because the information stored in DNA is so central to cellular function, it makes intuitive sense that the cell would make mRNA copies of this information for protein synthesis...

