Biomolecular condensation partitions cellular contents and has important roles in stress responses, maintaining homeostasis, development and disease. Many nuclear and cytoplasmic condensates are rich in RNA and RNA-binding proteins (RBPs), which undergo liquid–liquid phase separation (LLPS). Whereas the role of RBPs in condensates has been well studied, less attention has been paid to the contribution of RNA to LLPS. In this Review, we discuss the role of RNA in biomolecular condensation and highlight considerations for designing condensate reconstitution experiments. We focus on RNA properties such as composition, length, structure, modifications and expression level. These properties can modulate the biophysical features of native condensates, including their size, shape, viscosity, liquidity, surface tension and composition. We also discuss the role of RNA–protein condensates in development, disease and homeostasis, emphasizing how their properties and function can be determined by RNA. Finally, we discuss the multifaceted cellular functions of biomolecular condensates, including cell compartmentalization through RNA transport and localization, supporting catalytic processes, storage and inheritance of specific molecules, and buffering noise and responding to stress.

生物分子缩合划分细胞内容物，在应激反应、维持体内平衡、发育和疾病中具有重要作用。许多核和细胞质凝聚物富含 RNA 和 RNA 结合蛋白 (RBP)，它们会经历液-液相分离 (LLPS)。尽管 RBP 在冷凝物中的作用已得到充分研究，但人们很少关注 RNA 对 LLPS 的贡献。在这篇综述中，我们讨论了 RNA 在生物分子凝聚中的作用，并强调了设计凝聚物重构实验的注意事项。我们专注于 RNA 特性，如组成、长度、结构、修饰和表达水平。这些特性可以调节天然缩合物的生物物理特征，包括它们的尺寸、形状、粘度、流动性、表面张力和成分。我们还讨论了 RNA-蛋白质缩合物在发育、疾病和体内平衡中的作用，强调它们的特性和功能如何由 RNA 决定。最后，我们讨论了生物分子凝聚物的多方面细胞功能，包括通过 RNA 运输和定位进行细胞区室化、支持催化过程、特定分子的存储和遗传、缓冲噪音和响应压力。