Theory of rheology and aging of protein condensates

The material properties of biological condensates are deemed to play essential roles in cellular functions. The quantitative studies of condensates' rheology, however, became available very recently. The study shows the glass-like behavior of the protein condensates. In this study, we develop a rheological model of biological condensates which shows the experimentally observed features. Starting from physical pictures for the diffusion and stochastic binding of proteins inside condensates, we obtain the constitutive equation for the material property of protein condensates showing aging behavior. We elucidate how aging manifests in the experimental observations in microrheology, both in active and passive rheology. To understand the condensates' aging behavior, we also develop a novel method to characterize the time-dependent rheological properties of aging materials.