Intrinsically disordered regions and RNA binding domains contribute to protein enrichment in biomolecular condensates in oocytes.

Proteins containing both intrinsically disordered regions (IDRs) and RNA binding domains (RBDs) can phase separate , forming bodies similar to cellular biomolecular condensates. However, how IDR and RBD domains contribute to recruitment of proteins to biomolecular condensates remains poorly understood. Here, we analyzed the roles of IDRs and RBDs in L-bodies, biomolecular condensates present in oocytes. We show that a cytoplasmic isoform of hnRNPAB, which contains two RBDs and an IDR, is highly enriched in L-bodies. While both of these domains contribute to hnRNPAB self-association and phase separation and mediate enrichment into L-bodies in oocytes, neither the RBDs nor the IDR replicate the localization of full-length hnRNPAB. Our results suggest a model where the additive effects of the IDR and RBDs regulate hnRNPAB partitioning into L-bodies. This model likely has widespread applications as proteins containing RBD and IDR domains are common biomolecular condensate residents.