Molecules of the ganglioside GM1 are randomly distributed in liquid-crystalline 1-palmitoyl-2-oleoyl phosphatidylcholine bilayers. This conclusion is based on a freeze-etch electron microscopic study using ferritin-conjugated cholera toxin and cholera toxin alone as ganglioside labels. The average number of GM1 molecules under a label is calculated by a novel method from the dependence of the fraction of bilayer area covered by the label on the mole fraction of GM1 in the bilayer.
Bibliographical noteFunding Information:
We wish to thank Dr. John Heuser of Washington University for preparing samples with his liquid-helium freezing device. We also wish to acknowledge the advice and helpful criticisms of Dr. IstvMa Sughr. This study was supported by U.S. Public Health Service grants GM-23573 and GM-26234.
- Cholera toxin
- Electron microscopy
- Ganglioside distribution
- Phospholipid bilayer