Puromycin reactivity does not accurately localize translation at the subcellular level

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.