Biomolecular condensate formation requires multivalent interactions and rapid turnover. Stress granules are condensates formed through RNA–protein interactions under stress, requiring the RNA-binding protein G3BP. Parker et al. show that G3BP1 is an RNA condenser and promotes initial RNA–RNA interactions but is dispensable for stability; instead, stability requires RNA–RNA interactions.

The authors tested in vitro models of RNA granules and found that granules persisted despite proteinase digestion of G3BP1 only after sufficient ageing, or time, to form RNA–RNA interactions. RNA denaturation solubilized, whereas crosslinking stabilized, granules. The authors also suggest that RNA–RNA interactions were intermolecular higher-order assemblies.