Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.30.273748v1?rss=1 Authors: Kaur, T., Raju, M., Alshareedah, I., Davis, R. B., Potoyan, D. A., Banerjee, P. R. Abstract: Multivalent protein-protein and protein-RNA interactions are the drivers of biological phase separation. Bio-condensates typically contain a dense network of multiple proteins and RNAs, yet the role of overlapping molecular interactions in regulating the condensate composition and structure is not well understood. Employing a ternary system comprising of a prion-like polypeptide (PLD), arginine-rich polypeptide (RLD), and RNA, here we show that competition between the PLD and RNA for a single shared partner, the RLD, leads to PLD-RLD demixing and spontaneous formation of biphasic condensates. Combining experiments with simulations, we show that the topology of coexisting condensates is regulated via mixture composition and the nature of protein-protein and protein-RNA interactions, giving rise to a diverse set of multiphasic patterns including completely separated, partially and completely engulfed droplet morphologies, and Janus droplets. Our findings provide a minimal set of physical rules that govern the composition and spatial organization of multicomponent and multiphasic bio-condensates. Copy rights belong to original authors. Visit the link for more info