Using lipid binding proteins and advanced microscopy to study lipid domains.

Sphingomyelin is postulated to form clusters with glycosphingolipids, cholesterol and other sphingomyelin molecules in biomembranes through hydrophobic interaction and hydrogen bonds. These clusters form submicron size lipid domains. Proteins that selectively binds sphingomyelin and/or cholesterol are useful to visualize the lipid domains. Due to their small size, visualization of lipid domains requires advanced microscopy techniques in addition to lipid binding proteins. This Chapter describes the method to characterize plasma membrane sphingomyelin-rich and cholesterol-rich lipid domains by quantitative microscopy. This Chapter also compares different permeabilization methods to visualize intracellular lipid domains.