Imaging the Lipid and Cholesterol Distribution within the Plasma Membranes of Intact Cells with High-Resolution Imaging Mass Spectrometry

Domains enriched with cholesterol and sphingolipids, often referred to as lipid rafts, are believed to be present in the plasma membrane and correlate important cellular functions. Characterizing the sizes, shapes, and precise compositions of these membrane domains is especially challenging due to the lack of methods to acquire chemically specific information with high lateral resolution. Here we use a combination of stable isotope labeling and high resolution imaging mass spectrometry to chemically image the sphingolipid and cholesterol distribution within the plasma membrane with at least 100-nm-lateral resolution. Statistical methods are used to quantitatively assess the presence of cholesterol and sphingolipid-enriched domains in the plasma membrane.