When Separation Strengthens Ties

Phase separation underlies functional compartmentalization in living systems. Two recent studies ( Beutel et al. and Schwayer et al. ) show that zonula occludens (ZO) proteins of tight junctions (TJs) condense into compartments within the cytoplasm that display liquid properties. This ability to condense predicts normal TJ assembly and epithelial barrier function which are essential for vertebrate embryogenesis.