Fig. 8

PI(3,4)P₂/PI(4,5)P₂ headgroup facilitates specific membrane targeting. a Membrane association analyses with liposomes supplemented with indicated lipids. The ratio of ORP-ORD and indicated lipid is 1:5. The last two lanes are from a separate experiment. b Kinetic analyses of DHE extraction in the absence or presence of PI(3,4)P₂ (mean ± s.e.m., n = 3). c Representative time traces of DHE extraction by ORP1-ORD (1.5 μM). d Structure of ORP1-ORD in complex with PI(4,5)P₂. The PI(4,5)P₂ ligand is highlighted as cyan stick. e Close-up view of PI(4,5)P₂ headgroup binding at the tunnel entrance of ORP1-ORD (Mol A). f, g Effects of tunnel entrance mutations on the bound fraction of ORP1-ORD with PI(3,4)P₂-containing liposomes (f) and the initial rates of PI(3,4)P₂-dependent DHE transport with both lipids embedded in the donor liposomes (g). (For all bar graphs, data are shown as mean ± s.e.m. (error bar), n = 3.)