Supported lipid bilayer

Supported lipid bilayers consisted of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC; Avanti Polar Lipids, Alabaster, AL) with a small admixture of Texas Red and BODIPY FL conjugated to DHPE lipids (Thermo Fisher Scientific, Waltham, MA) to provide fluorescent labels. The lipids were mixed in chloroform at a 1:3300 ratio (BODIPY FL DHPE:POPC) and a 1:1100 ratio (Texas Red DHPE:POPC) and dried under nitrogen flow. Dried lipids were mixed with PBS to form large unilamellar vesicles, which were then extruded to generate small unilamellar vesicles (SUVs) using a 100 nm filter and the NanoSizer MINI Liposome Extruder (T & T Scientific, Knoxville, TN) according to manufacturer instructions. Coverslips were cleaned by brief exposure to a butane flame, followed by ∼1 h of etching in 50/50 w/w KOH solution. The SUV solution was added to each coverslip for 15 min, followed by a wash with PBS to remove any free-floating SUVs.