Schematic representation visualizing the major findings of the study. The study reveals the presence of distributed nanocores within the mobile, liquid droplet-like phase of SGs. The two RBPs, G3BP1 (green arrows) and IMP1 (red arrows), exhibit markedly different SG–cytosol interconversion dynamics. Within granules, both RBPs exhibit alternating binding in the nanocores and liquid droplet-like diffusion in the mobile phase.