Interplay between membranes and biomolecular condensates in the regulation of membrane-associated cellular processes

Liquid‒liquid phase separation (LLPS) has emerged as a key mechanism for organizing cellular spaces independent of membranes. Biomolecular condensates, which assemble through LLPS, exhibit distinctive liquid droplet-like behavior and can exchange constituents with their surroundings. The regulation of condensate phases, including transitions from a liquid state to gel or irreversible aggregates, is important for their physiological functions and for controlling pathological progression, as observed in neurodegenerative diseases and cancer. While early studies on biomolecular condensates focused primarily on those in fluidic environments such as the cytosol, recent discoveries have revealed their existence in close proximity to, on, or even comprising membranes. The aim of this review is to provide an overview of the properties of membrane-associated condensates in a cellular context and their biological functions in relation to membranes.