Cellular liquid–liquid phase separation: Concept, functions, regulations, and detections

Liquid–liquid phase separation is a multicomponent system separated into phases with different compositions and structures. It has been identified and explored in organisms after being introduced from the thermodynamic field. Condensate, the product of phase separation, exists in different scales of cellular structures, such as nucleolus, stress granules, and other organelles in nuclei or cytoplasm. And also play critical roles in different cellular behaviors. Here, we review the concept, thermodynamical and biochemical principles of phase separation. We summarized the main functions including the adjustment of biochemical reaction rates, the regulation of macromolecule folding state, subcellular structural support, the mediation of subcellular location, and intimately linked to different kinds of diseases, such as cancer and neurodegeneration. Advanced detection methods to investigate phase separation are collected and analyzed. We conclude with the discussion of anxiety of phase separation, and thought about how progress can be made to develop precise detection methods and disclose the potential application of condensates.