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Initiation of Translation02:33

Initiation of Translation

40.8K
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...
40.8K
Initiation of Translation02:33

Initiation of Translation

8.8K
8.8K
Leaky Scanning02:28

Leaky Scanning

5.9K
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...
5.9K
Translation in Prokaryotes01:29

Translation in Prokaryotes

2.7K
Prokaryote translation is a complex, highly coordinated process that converts genetic information from mRNA into functional proteins. It involves three stages: initiation, elongation, and termination, each facilitated by specific molecular components.Initiation of TranslationThe process begins with the assembly of the ribosomal subunits and initiation factors on the mRNA. In bacteria, the 30S ribosomal subunit recognizes the Shine-Dalgarno sequence in the mRNA, a conserved region upstream of...
2.7K
Improving Translational Accuracy02:07

Improving Translational Accuracy

15.7K
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...
15.7K
pre-mRNA Processing02:01

pre-mRNA Processing

59.1K
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...
59.1K

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関連する実験動画

Updated: Apr 20, 2026

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
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Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs

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構造的な変化により,真核細胞の翻訳開始複合体によるスタートコドンの認識が可能になります.

Tanweer Hussain1, Jose L Llácer1, Israel S Fernández1

  • 1MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.

Cell
|November 24, 2014
PubMed
まとめ

ユカリオットトランスレーション開始は,イニシアターtRNAがmRNAスキャンのためにPOUTコンフォームを採用することを含む. AUGが認識されると,PIN状態にイソメリズされ,コドン-アンチコドン複合体を安定させ,スタートコドン認識を容易にする.

さらに関連する動画

Xenopus laevis as a Model to Identify Translation Impairment
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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Published on: May 19, 2014

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関連する実験動画

Last Updated: Apr 20, 2026

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
10:37

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs

Published on: May 10, 2018

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Xenopus laevis as a Model to Identify Translation Impairment
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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
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科学分野:

  • 分子生物学は分子生物学である.
  • 構造生物学 構造生物学とは
  • バイオケミストリー バイオケミストリー

背景:

  • ユカリオットトランスレーションの開始は,複数のタンパク質因子と40Sリボソームサブユニットを含む複雑なプロセスです.
  • イニシエーターtRNAは,最初に非正規のPOUTコンフォームに結合し,mRNAスキャンを可能にします.
  • スタートコドン認識は,PIN状態の構成的変化を誘発し,これは翻訳に不可欠です.

研究 の 目的:

  • ユカリオットの翻訳開始時のPIN状態の構造的基礎を解明する.
  • クリオ電子顕微鏡を用いて,PIN状態のイニシアターtRNAと酵母前始動複合体を視覚化します.
  • スタートコドン認識複合体の安定化における開始因子の役割を理解する.

主な方法:

  • クリオ電子顕微鏡 (cryo-EM) による酵母前始動複合体の再構築.
  • 高解像度構造分析 (4.0 Å 解像度).

主要な成果:

  • PIN状態のイニシアターtRNAを持つ酵母前始動複合体の冷凍-EM構造が決定されました.
  • ユカリオット始動因子1A (eIF1A) のN端尾は,コドン-アンチコドン複合体を安定させる.
  • ユカリオット開始因子1 (eIF1) とユカリオット開始因子2 (eIF2) の形状の変化が観察され,eIF1の放出とコドン認識の開始を促進しました.
  • mRNAは,eIF2?,eIF1A,およびリボソームの要素と相互作用し,コンテキスト・ヌクレオチドの認識を可能にします.

結論:

  • PIN状態は,eIF1Aと主要なリボソーム要素を含む相互作用によって安定化されます.
  • eIF1とeIF2の構造的再編成は,スキャンからコドン認識への移行に不可欠です.
  • この構造は,リボソームがAUGスタートコドンとその周囲の文脈を翻訳開始時にどのように認識するかについての洞察を提供します.