 Epsin causes a strong degree of membrane curvature and tubulation, even fragmentation of membranes with a high PtdIns(4,5)P2 content.Epsin binding to membranes facilitates their deformation by insertion of the N-terminal helix into the inner leaflet of the bilayer, pushing the head groups apart.This would reduce the energy needed to curve the membrane into a vesicle, making it easier for the clathrin cage to fix and stabilise the curved membrane.