G3BP–Caprin1–USP10 complexes mediate stress granule condensation and associate with 40S subunits

Cells lacking both G3BP1 and G3BP2 cannot form stress granules in response to certain stressors.

• G3BP1 and G3BP2 are essential for stress granule formation in response to eukaryotic initiation factor 2α phosphorylation or eIF4A inhibition.
• Cells can still form stress granules when exposed to severe heat or osmotic stress, indicating alternative pathways for granule assembly.
• Phosphomimetic G3BP1-S149E does not facilitate stress granule formation, while G3BP1-F33W can rescue it despite not binding to certain partner proteins.
• Binding of Caprin1 to G3BP promotes stress granule formation, whereas binding of USP10 inhibits it.
• G3BP interacts with ribosomal subunits, and this interaction is crucial for its role in stress granule formation.

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