Photoreactive probes for high resolution mapping of membrane proteins

The preparation and characterization of a novel series of radioactively labeled membrane probes is described. These probes are carbohydrate derivatives of fatty acids which contain a photosensitive azide moiety at a specified distance along the alkyl chain. The function of the carbohydrate group is to restrict the azide function to the outer surface monolayer of sealed membrane systems. The azide probes have been used in several well-characterized membrane systems including erythrocyte ghosts, membrane-enveloped viruses, and artificial vesicles. Upon activation, the probes attach to integral proteins to form a stable, covalent complex which may be extracted and identified. The activation protocol is outlined and some of the preliminary results are discussed.