Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

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

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Activation of the mRNA Decay-Associated DEAD-Box ATPase Dhh1 Requires Deadenylation and Decapping Factors.

bioRxiv : the preprint server for biology·2026
Same author

Structural insights into the recruitment of viral type 2 IRES to ribosomal preinitiation complex for protein synthesis.

eLife·2026
Same author

Temperate phages enhance bacterial host fitness via RNA-guided flagellar remodelling.

Nature microbiology·2026
Same author

Suppression of upstream ORF translation is not a widespread mechanism of translational stimulation by yeast helicase Ded1.

Nucleic acids research·2026
Same author

Suppression of upstream ORF translation is not a widespread mechanism of translational stimulation by yeast helicase Ded1.

bioRxiv : the preprint server for biology·2026
Same author

Novel insights into the assembly of the yeast translation initiation multifactor complex: The critical role of eIF5.

Protein science : a publication of the Protein Society·2026

Related Experiment Video

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

13.4K

Structural changes enable start codon recognition by the eukaryotic translation initiation complex.

Tanweer Hussain1, Jose L Llácer1, Israel S Fernández1

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

Cell
|November 24, 2014
PubMed
Summary

Eukaryotic translation initiation involves the initiator tRNA adopting a POUT conformation for mRNA scanning. Upon AUG recognition, it isomerizes to a PIN state, stabilizing the codon-anticodon duplex and facilitating start codon recognition.

More Related Videos

Xenopus laevis as a Model to Identify Translation Impairment
10:24

Xenopus laevis as a Model to Identify Translation Impairment

Published on: September 27, 2015

11.2K
Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
10:59

Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Published on: May 19, 2014

19.0K

Related Experiment Videos

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

13.4K
Xenopus laevis as a Model to Identify Translation Impairment
10:24

Xenopus laevis as a Model to Identify Translation Impairment

Published on: September 27, 2015

11.2K
Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
10:59

Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Published on: May 19, 2014

19.0K

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • Eukaryotic translation initiation is a complex process involving multiple protein factors and the 40S ribosomal subunit.
  • The initiator tRNA initially binds in a non-canonical POUT conformation, allowing for mRNA scanning.
  • Start codon recognition triggers a conformational change to the PIN state, which is crucial for translation.

Purpose of the Study:

  • To elucidate the structural basis of the PIN state during eukaryotic translation initiation.
  • To visualize the yeast preinitiation complex with initiator tRNA in the PIN state using cryo-electron microscopy.
  • To understand the role of initiation factors in stabilizing the start codon recognition complex.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) reconstruction of a yeast preinitiation complex.
  • High-resolution structural analysis (4.0 Å resolution).

Main Results:

  • A cryo-EM structure of the yeast preinitiation complex with initiator tRNA in the PIN state was determined.
  • The N-terminal tail of eukaryotic initiation factor 1A (eIF1A) stabilizes the codon-anticodon duplex.
  • Conformational changes in eukaryotic initiation factor 1 (eIF1) and eukaryotic initiation factor 2 (eIF2) were observed, facilitating eIF1 release and start codon recognition.
  • mRNA interacts with eIF2?, eIF1A, and ribosomal elements, enabling context nucleotide recognition.

Conclusions:

  • The PIN state is stabilized by interactions involving eIF1A and key ribosomal elements.
  • Structural rearrangements in eIF1 and eIF2 are critical for the transition from scanning to start codon recognition.
  • The structure provides insights into how the ribosome recognizes the AUG start codon and its surrounding context during translation initiation.