Nanoscale Analysis of Glycolipid Distribution in the Cell Membrane

Biological membranes at ambient temperature show fluidity in two dimensions. Both proteins and lipids, however, do not necessarily distribute evenly but often have a biased distribution. Methods to visualize membrane lipids are limited compared to those for membrane proteins, and distribution of endogenous lipids has been difficult to analyze quantitatively. We recently developed a method to immobilize membrane lipids physically by combining quick freezing and freeze-fracture techniques, whereby we could observe their two-dimensional distribution at the nanoscale. The method has a high capture ratio, and the point pattern analyses can be applied to the result. This article mainly discussed the results obtained for gangliosides GM1 and GM3 and also referred to the results for phosphatidylinositol 4,5-bisphosphate.