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Updated: Jul 24, 2026
10:37
Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
Published on: May 10, 2018
Facile characterization of translation initiation via nonsense codon suppression
A V Karginov1, M Lodder, S M Hecht
1Department of Chemistry and Department of Biology, University of Virginia, Charlottesville, VA 22901, USA.
Nucleic Acids Research
|August 24, 1999
Summary
Researchers developed a novel in vitro method to track protein translation initiation in eukaryotes. This strategy uses fluorescent amino acids to monitor translation efficiency at AUG codons, aiding in the study of gene expression mechanisms.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Understanding translation initiation is crucial for controlling gene expression.
- Current methods for studying translation initiation efficiency have limitations.
- Eukaryotic translation initiation is a complex process involving multiple factors.
Purpose of the Study:
- To develop a novel strategy for studying the mechanism of translation initiation in eukaryotes.
- To monitor translation initiation efficiency at an AUG codon in different contexts.
- To characterize the translation initiation process using fluorescence measurements.
Main Methods:
- Developed an in vitro translation system.
- Incorporated a non-natural fluorescent amino acid into a protein using a suppressor tRNAPheCUA.
- Analyzed translation initiation efficiency using fluorescence measurements of mRNA constructs in rabbit reticulocyte lysate.
Main Results:
- Successfully incorporated a non-natural fluorescent amino acid into proteins.
- Demonstrated the ability to monitor translation initiation efficiency at AUG codons.
- Observed differences in translation initiation position and efficiency based on mRNA constructs.
Conclusions:
- The developed strategy provides a new method for studying eukaryotic translation initiation.
- Fluorescence measurements can effectively characterize the translation initiation process.
- This approach allows for the analysis of translation initiation in different sequence contexts.
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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...
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02:33Initiation 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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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...
02:27Nonsense-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,...
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