The ENTH domain is a membrane binding domain which is found in members of the epsin protein family. In epsin-1 it shows specificity for the membrane glycophospholipid phosphatidylinositol-4,5-bisphosphate (pi-4,5-bp), however not all ENTH domains bind to this molecule. Binding causes tubulation of liposomes and in vivo this membrane-binding function is normally coordinated with clathrin polymerisation.
When pi-4,5-bp binds to the domain an additional helix folds around the headgroup (helix 0) and thus the lipid headgroup gets buried in a pocket. The outer surface of this new helix is hydrophobic and inserts into the membrane like a wedge and helps to drive membrane curvature.
Ford, M.G.J., Mills, I.G., Peter, B.J., Vallis, Y., Praefcke, G.J.K., Evans, P.R. and McMahon, H.T. (2002) Curvature of clathrin-coated pits driven by epsin. Nature 419, 361-366. pubmed