asialo-gm1-ganglioside and 1-2-oleoylphosphatidylcholine

Multilamellar liposomes composed of 1:1 dielaidoylphosphatidylcholine: dipalmitoylphosphatidylcholine at 20 degrees C contain laterally separated gel and liquid-crystalline phases that can be identified by electron microscopy in freeze-etch replicas on the basis of their distinctive morphology. Visualization of marker proteins that specifically bind to glycosphingolipids included in these liposomes has revealed that, at 1 mol % or less, the ganglioside GM1 and the neutral asialo-GM1 derived from it are localized within the gel-phase regions exclusively. Increasing the mole fraction of the glycosphingolipids results in the appearance of marker in the fluid-phase regions. Another neutral glycosphingolipid, Forssman, does not display a phase preference and is found in both phases at a low mole percent. The phase preference of these three glycosphingolipids depends primarily upon interactions between the hydrophobic moieties of these molecules and the matrix phosphatidylcholines.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Cholera Toxin; Freeze Etching; G(M1) Ganglioside; Gels; Glycosphingolipids; Kinetics; Lipid Bilayers; Microscopy, Electron; Phosphatidylcholines