Membrane bending by protein phase separation

Cellular membranes take on an elaborate set of highly curved and bent shapes which are essential to diverse cellular functions from endocytosis to cell division. The prevailing view has been that membrane bending is driven by proteins with curved shapes, which assemble at the membrane surface to form solid scaffolds. In contrast, here we show that proteins which form liquid-like assemblies on membranes are also potent drivers of bending. These “liquid scaffolds” apply compressive stress to the membrane surface, generating a diverse and dynamic family of membrane shapes. These data, which come at a time when liquid-like protein assemblies are being identified throughout the cell, suggest that protein liquids may play an important role in shaping cellular membranes.