Translation landscape of stress granules.

Stress granules, cytoplasmic assemblies of RNA binding proteins and messenger RNAs formed during cellular stress, are implicated in translational control. However, their exact functions remain elusive. Here, we used cryogenic correlative light and electron microscopy to visualize stress granules in their native environment and reconstructed them in three dimensions using tomography. This approach provided the first quantitative and spatial analysis of the translational machinery within stress granules. Our findings suggest that stress granules have a limited impact on global translation regulation but serve to protect small ribosomal subunits and preinitiation complexes from degradation. Numerical simulations based on a phase-field model accurately reproduced the spatial distribution of ribosomal components inside and outside the stress granules, shedding light on the thermodynamic principles governing this process.