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A cellular protein that binds to the 5'-noncoding region of poliovirus RNA: implications for internal translation
K Meerovitch1, J Pelletier, N Sonenberg
1Department of Biochemistry, McGill University, Montréal, Canada.
Abstract:
Initiation of translation on poliovirus mRNA occurs by internal binding of ribosomes to a region within the 5'-noncoding portion of the mRNA. The mechanistic details and trans-acting factors involved in this event are not understood fully. We used a mobility-shift electrophoresis assay to identify a specific RNA-protein complex, which can form between an RNA fragment that contains nucleotides 559-624 of the poliovirus 5' UTR (untranslated region) and a component or components of a HeLa cell extract. Complex formation was reduced greatly in a reticulocyte lysate or a wheat-germ extract. A 52-kD polypeptide (p52) has been identified as part of the protein-RNA complex by use of an UV cross-linking assay. This polypeptide apparently is not a known translation initiation or elongation factor. The possible involvement of p52 in translation initiation of poliovirus protein synthesis is discussed.
Insights
Researchers identified a specific protein complex involved in poliovirus translation initiation. This complex, containing a 52-kD polypeptide (p52), binds to the poliovirus 5
Area of Science:
- Molecular Biology
- Virology
- Protein Synthesis
Background:
- Poliovirus mRNA translation initiation involves internal ribosome binding to the 5'-untranslated region (UTR).
- The precise mechanisms and protein factors governing this internal binding are not fully elucidated.
Purpose of the Study:
- To identify specific RNA-protein interactions and trans-acting factors involved in poliovirus translation initiation.
- To characterize the protein component(s) interacting with the poliovirus 5' UTR.
Main Methods:
- Mobility-shift electrophoresis assay to detect RNA-protein complex formation.
- UV cross-linking assay to identify and characterize the protein component of the complex.
- Comparative analysis of complex formation in different cellular extracts (HeLa, reticulocyte lysate, wheat-germ).
Main Results:
- A specific RNA-protein complex was identified between a poliovirus 5' UTR fragment (nucleotides 559-624) and HeLa cell extract components.
- Complex formation was significantly reduced in reticulocyte lysate and wheat-germ extracts, suggesting cell-specific factors.
- A 52-kD polypeptide (p52) was identified as a component of this RNA-protein complex.
Conclusions:
- The 52-kD polypeptide (p52) is a potential trans-acting factor involved in poliovirus translation initiation.
- p52 does not appear to be a known translation initiation or elongation factor, indicating a novel role.
- Further investigation is warranted to confirm the functional involvement of p52 in poliovirus protein synthesis.