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Updated: May 24, 2025

Quantitative Immunofluorescence to Measure Global Localized Translation
Published on: August 22, 2017
A subcellular map of translational machinery composition and regulation at the single-molecule level
Zijian Zhang1,2, Adele Xu2, Yunhao Bai3,4
1Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford, CA, USA.
Abstract:
Millions of ribosomes are packed within mammalian cells, yet we lack tools to visualize them in toto and characterize their subcellular composition. In this study, we present ribosome expansion microscopy (RiboExM) to visualize individual ribosomes and an optogenetic proximity-labeling technique (ALIBi) to probe their composition. We generated a super-resolution ribosomal map, revealing subcellular translational hotspots and enrichment of 60S subunits near polysomes at the endoplasmic reticulum (ER). We found that Lsg1 tethers 60S to the ER and regulates translation of select proteins. Additionally, we discovered ribosome heterogeneity at mitochondria guiding translation of metabolism-related transcripts. Lastly, we visualized ribosomes in neurons, revealing a dynamic switch between monosomes and polysomes in neuronal translation. Together, these approaches enable exploration of ribosomal localization and composition at unprecedented resolution.
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