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Updated: Dec 10, 2025
Quantitative Immunofluorescence to Measure Global Localized Translation
Published on: August 22, 2017
Puromycin reactivity does not accurately localize translation at the subcellular level
Syed Usman Enam1,2, Boris Zinshteyn1,2, Daniel H Goldman1,2
1Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States.
Abstract:
Puromycin is a tyrosyl-tRNA mimic that blocks translation by labeling and releasing elongating polypeptide chains from translating ribosomes. Puromycin has been used in molecular biology research for decades as a translation inhibitor. The development of puromycin antibodies and derivatized puromycin analogs has enabled the quantification of active translation in bulk and single-cell assays. More recently, in vivo puromycylation assays have become popular tools for localizing translating ribosomes in cells. These assays often use elongation inhibitors to purportedly inhibit the release of puromycin-labeled nascent peptides from ribosomes. Using in vitro and in vivo experiments in various eukaryotic systems, we demonstrate that, even in the presence of elongation inhibitors, puromycylated peptides are released and diffuse away from ribosomes. Puromycylation assays reveal subcellular sites, such as nuclei, where puromycylated peptides accumulate post-release and which do not necessarily coincide with sites of active translation. Our findings urge caution when interpreting puromycylation assays in vivo.
Insights
Puromycin assays, used to track protein synthesis, may mislead researchers. Puromycylated peptides are released from ribosomes and can accumulate in areas without active translation, requiring caution in interpretation.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Puromycin is a translation inhibitor and tyrosyl-tRNA mimic.
- Puromycin assays quantify active translation and localize translating ribosomes.
- Current in vivo assays often use elongation inhibitors to prevent peptide release.
Purpose of the Study:
- To investigate the release and localization of puromycin-labeled peptides in vivo.
- To evaluate the accuracy of in vivo puromycylation assays for identifying sites of active translation.
Main Methods:
- In vitro and in vivo experiments in eukaryotic systems.
- Puromycylation assays with and without elongation inhibitors.
- Analysis of puromycylated peptide localization within cells.
Main Results:
- Puromycylated peptides are released from ribosomes even with elongation inhibitors present.
- Released peptides diffuse and can accumulate in subcellular locations, such as nuclei.
- These accumulation sites do not always correlate with active translation sites.
Conclusions:
- Puromycylation assays may misrepresent the sites of active translation due to peptide diffusion post-release.
- Caution is advised when interpreting in vivo puromycylation assay results.
- Findings highlight the need for re-evaluation of puromycylation assay interpretation in cellular localization studies.
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