関連する実験動画

Updated: Jul 14, 2026

Eukaryotic Polyribosome Profile Analysis

Published on: June 15, 2010

酵母eIF-2β遺伝子のZn(II) 指モチーフの変異は,スキャンプロセス中にリボソームの開始部位の選択を変化させます

T F Donahue¹, A M Cigan, E K Pabich

¹Department of Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611.

|August 26, 1988

まとめ

酵母翻訳開始因子eIF-2βサブユニット (SUI3) の変異により,標準的なAUGスタートコドンなしで遺伝子発現が可能になります. この発見は,スタートコドン認識におけるスキャンリボソームの役割を強調しています.

科学分野:

分子生物学は分子生物学である.
遺伝学遺伝学とは
バイオケミストリーバイオケミストリー

背景:

HIS4遺伝子の変異は,タンパク質合成の正常な開始を阻害する.
これらの変異の抑制剤を特定することで,翻訳機構の重要な構成要素を明らかにすることができます.

研究の目的:

イーストにおけるイニシアターコドン変異を抑制する遺伝子を特定し,特徴づけること.
トランスレーション開始における特定された遺伝子の役割を明らかにする.

主な方法:

HIS4イニシアターコドン変異体の抑制剤の遺伝子スクリーニング.
抑制遺伝子の分子および生化学的特徴.
酵母とヒトの遺伝子のタンパク質配列分析と比較.

主要な成果:

3つの遺伝子 (sui1, sui2, SUI3) が抑制剤として特定されました.
SUI3は,真核細胞の翻訳開始因子2 (eIF-2) のβサブユニットをコードする.
SUI3の変異は,保存された Zn(II) 指モチーフに影響し,AUG以外のコードン (UUG) でイニシアチブを可能にします.

結論:

eIF-2のβサブユニットは,翻訳中のスタートコドン認識において重要な役割を果たします.
eIF-2内の核酸結合ドメインは,リボソームスキャンプロセスに関与しています.
これらの発見は,タンパク質合成の開始の基本的メカニズムについての理解を深める.

さらに関連する動画

Xenopus laevis as a Model to Identify Translation Impairment

Xenopus laevis as a Model to Identify Translation Impairment

Published on: September 27, 2015

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs

Published on: May 10, 2018

関連する概念動画

Improving Translational Accuracy

Improving Translational Accuracy

Base complementarity between the three base pairs of mRNA codon and the tRNA anticodon is not a failsafe mechanism. Inaccuracies can range from a single mismatch to no correct base pairing at all. The free energy difference between the correct and nearly correct base pairs can be as small as 3 kcal/ mol. With complementarity being the only proofreading step, the estimated error frequency would be one wrong amino acid in every 100 amino acids incorporated. However, error frequencies observed in...

Initiation of Translation

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...

Nonsense-mediated mRNA Decay

Nonsense-mediated mRNA Decay

The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...

Riboswitches

Riboswitches

Riboswitches are non-coding mRNA domains that regulate the transcription and translation of downstream genes without the help of proteins. Riboswitches bind directly to a metabolite and can form unique stem-loop or hairpin structures in response to the amount of the metabolite present. They have two distinct regions – a metabolite-binding aptamer and an expression platform.
The aptamer has high specificity for a particular metabolite which allows riboswitches to specifically regulate...

Leaky Scanning

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...

Mismatch Repair

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...