Phospho-dependent phase separation of FMRP and CAPRIN1 recapitulates regulation of translation and deadenylation

Keeping RNA processing contained Biomolecular condensates that assemble by phase separation are involved in RNA processing. Posttranslational modifications in intrinsically disordered regions of proteins can regulate RNA processing by regulating phase separation. Kim et al. used nuclear magnetic resonance spectroscopy to characterize phase separation in a model system comprising the C-terminal disordered regions of the translational regulators FMRP and CAPRIN1 that repress translation by deadenylating mRNA. Interactions between the proteins involve specific sequences in FMRP and CAPRIN1, and the propensity for mRNA to partition into the condensates depends on the phosphorylation patterns in the disordered regions. This mechanism integrates signaling pathways with the regulation of RNA processing. Science , this issue p. 825