IRSp53 senses negative membrane curvature and phase separates along membrane tubules

摘要: BAR domain proteins contribute to membrane deformation in diverse cellular processes. The inverted-BAR (I-BAR) protein IRSp53, for instance, is found on the inner leaflet of tubular filopodia; however its role formation these structures incompletely understood. Here we develop an original assay which are encapsulated giant unilamellar vesicles connected nanotubes. Our results demonstrate that I-BAR dimers sense negative curvature. Experiment and theory reveal displays a non-monotonic sorting with curvature, expands tube at high imposed tension while constricting it low tension. Strikingly, density tension, protein-rich domains appear along tube. This peculiar behaviour due shallow intrinsic curvature dimers. It allows constriction weakly curved membranes coupled local enrichment biologically relevant conditions. might explain how IRSp53 contributes vivo initiation filopodia.