Cell Surface Protein Biotinylation for SDS-PAGE Analysis

Proteins expressed at the cell surface play important roles in physiology and represent valuable targets for new therapeutic agents. Indeed, the so-called druggable proteome consists, for about two thirds, of proteins that are either integral to or associated with the cell membrane. In spite of its importance, however, a complete characterization of the cell surface proteome has remained elusive because of the difficulty to efficiently purify these proteins from other contaminants. Methods exploiting the strong interaction between biotin and streptavidin have paved the way for the most significant advances in this field. The present chapter focuses on techniques for cell surface biotinylation with commercially available reagents and capture by avidin affinity chromatography and release of the biotinylated surface proteins for downstream analysis by electrophoretic methods.