Plane order parameter. Plane order parameter of the bilayer surface, SPOP, at the top leaflet (solid bars) and at the bottom leaflet (gray bars) of the lipid bilayer. The PG-1 β-sheet is located at the top leaflet of the lipid bilayer.
Jang et al. BMC Structural Biology 2007 7:21 doi:10.1186/1472-6807-7-21