Asymmetric bilayers displaying Man 9 GlcNAc 2 -DPPE were supported on a gel phase DPPE monolayer (43 Å 2 per lipid). The DPPE was in turn supported on a mica sheet that was affixed to a hemicylindrical, silica disk. The outer layer contains 5 mol % of Man 9 GlcNAc 2 -DPPE mixed with DTPC (fluid, T m < 21°C) ( Figure 1C ) and was transferred by LangmuirÀBlodgett deposition from a subphase of buffer A at 21°C at 65.4 ( 0.8 Å 2 per DTPC. These neoglycolipid/DTPC monolayers are in the fluid state at 21°C. The molar concentrations of DPPE, DTPC, and Man 9 GlcNAc 2 -DPPE in stock solutions were determined with the Bartlett phosphorus assay. 24 At 5 mol % Man 9 GlcNAc 2 -DPPE in the outer leaflet, the average area per neoglycolipid is 7.7 Â 10 16 glycolipid/m 2 .