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Related Concept Videos

Improving Translational Accuracy02:07

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 Translation02:33

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.
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Leaky Scanning02:28

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...
General Transcription Factors01:30

General Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...
Initiation of Translation02:33

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Translation in Prokaryotes

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...

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Xenopus laevis as a Model to Identify Translation Impairment
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Published on: September 27, 2015

Minimum requirements for the function of eukaryotic translation initiation factor 2.

F L Erickson1, J Nika, S Rippel

  • 1Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083-0688, USA.

Genetics
|May 3, 2001
PubMed
Summary

Increasing eukaryotic translation initiation factor 2 (eIF2) levels bypasses the need for eIF2B and eIF2alpha, suggesting the eIF2betagamma complex performs essential functions alone.

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Rapid In Vivo Fixation and Isolation of Translational Complexes from Eukaryotic Cells

Published on: December 25, 2021

Area of Science:

  • Molecular Biology
  • Protein Synthesis
  • Gene Regulation

Background:

  • Eukaryotic translation initiation factor 2 (eIF2) facilitates tRNA delivery to ribosomes.
  • eIF2B is the guanine nucleotide exchange factor essential for eIF2 function.
  • eIF2alpha kinase PKR can be lethal when overexpressed.

Purpose of the Study:

  • To investigate the essential functions of eIF2 subunits.
  • To explore conditions that bypass the requirement for eIF2B and eIF2alpha.
  • To understand the regulation of ternary complex levels.

Main Methods:

  • In vivo experiments manipulating eIF2 levels and initiator tRNA.
  • Utilizing a yeast model with specific eIF2 mutations (gcd11-K250R).
  • Assessing the effects of PKR overexpression.

Main Results:

  • Elevated wild-type eIF2 bypasses the need for eIF2B in vivo.
  • These conditions suppress lethal PKR overexpression.
  • Bypassing eIF2B also overcomes the requirement for the essential eIF2alpha gene (SUI2).
  • A specific eIF2 mutation (gcd11-K250R) enhances these effects.

Conclusions:

  • The eIF2betagamma complex can perform essential functions without eIF2alpha and eIF2B.
  • eIF2B and eIF2alpha may primarily regulate ternary complex levels.
  • This suggests a simplified model for translation initiation regulation.