Free cholesterol in mammalian cells resides mostly in the plasma membrane, where it plays an important role in cellular homeostasis. We synthesized a new fluorescent cholesterol analogue that retained an intact alkyl chain and the sterane backbone of cholesterol. The hydroxyl group of cholesterol was converted into an amino group that was covalently linked to the fluorophore tetramethylrhodamine to retain the ability to form hydrogen bonds with adjacent molecules. Incubating live MDCK (Madin-Darby canine kidney) cells with our fluorescent cholesterol analogue resulted in the generation of intense signals that were detected by microscopy at the plasma membrane. Incubation with the analogue exerted minimal, if any, influence on cell growth, indicating that it could serve as a useful tool for analyzing free cholesterol at the plasma membrane.
Keywords: Chemical probe; Detergent-resistant membrane; Live-cell imaging; Microscopy; Sterol.
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