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Updated: Aug 21, 2026
Isolation of mRNAs Associated with Yeast Mitochondria to Study Mechanisms of Localized Translation
Published on: March 14, 2014
Isolation and identification of a protein binding to the localization element of Metallothionein-1 mRNA
I Mickleburgh1, B Burtle, D Nury
1Institute of Cell and Molecular Biosciences, University of Newcastle upon Tyne, UK.
Abstract:
mRNA localization provides a mechanism for localized protein synthesis. mRNAs encoding certain proteins, including c-MYC, c-FOS, MT-1 (Metallothionein-1) and vimentin, are localized around the nuclei of mammalian cells and are associated with the cytoskeleton. Targeting of these mRNAs to the perinuclear cytoplasm is mediated by elements within their 3'-UTRs (3'-untranslated regions), but many of the trans-acting proteins remain unidentified. UV cross-linking assays using radiolabelled transcripts indicated that a protein of approx. 50 kDa (from the Chinese-hamster ovary cell extracts) bound to the MT-1 3'-UTR sequence. Competition experiments using unlabelled mutant 3'-UTR RNAs revealed that the binding of this protein is specific to localization-positive mutants. Isolation of a 50 kDa protein was achieved by an RNA affinity-based method in which biotinylated MT-1 3'-UTR RNA was anchored to paramagnetic beads. Bound proteins were eluted and analysed by SDS/PAGE. The 50 kDa protein was extracted from the gel, subjected to trypsin digestion and identified by matrix-assisted laser-desorption/ionization-time-of-flight mass spectrometry as eukaryote elongation factor 1alpha.
Insights
Researchers identified a key protein involved in mRNA localization. Eukaryote elongation factor 1alpha binds to the Metallothionein-1 3'-untranslated region, directing mRNA to specific cellular locations for protein synthesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- mRNA localization is crucial for spatial control of protein synthesis in mammalian cells.
- Specific mRNAs, including Metallothionein-1 (MT-1), are targeted to the perinuclear cytoplasm via 3 -untranslated regions (3 -UTRs).
- The trans-acting factors mediating this mRNA targeting remain largely uncharacterized.
Purpose of the Study:
- To identify the trans-acting protein that binds to the MT-1 3 -UTR and mediates mRNA localization.
- To characterize the binding specificity of this protein to the MT-1 3 -UTR.
Main Methods:
- UV cross-linking assays with radiolabeled MT-1 3 -UTR RNA and Chinese hamster ovary cell extracts.
- Competition assays using unlabeled mutant 3 -UTR RNAs to assess binding specificity.
- RNA affinity purification using biotinylated MT-1 3 -UTR RNA immobilized on paramagnetic beads.
- Protein identification via SDS-PAGE, trypsin digestion, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS).
Main Results:
- A ~50 kDa protein was found to specifically bind to the MT-1 3 -UTR.
- Binding was confirmed to be sequence-specific, dependent on localization-positive elements within the 3 -UTR.
- The 50 kDa protein was isolated and identified as eukaryote elongation factor 1alpha (eEF1A).
Conclusions:
- Eukaryote elongation factor 1alpha is a trans-acting factor that binds to the MT-1 3 -UTR.
- This interaction plays a role in the perinuclear localization of MT-1 mRNA, contributing to localized protein synthesis.
- The identification of eEF1A provides a new molecular link in the pathway of mRNA localization and translational control.
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