Covalent labeling of protein with biotin (biotinylation) is a versatile technique which enables the capture and analysis of labeled protein with streptavidin-coated beads. It is particularly useful for detecting and quantifying the cell-surface expression of membrane proteins and widely used to analyze protein trafficking and the effect of mutations (particularly those which render the protein nonfunctional) on cell-surface expression. Here I describe the procedure for biotinylation and capture of cell-surface rat P2X2 receptors expressed in mammalian cells, and outline the steps in data analysis required to measure the proportion of cell-surface expressed protein of single point mutants relative to a wild-type control.
Keywords: Biotinylation; Cell-surface; Crosslinking; Membrane protein; P2X; Protein expression; Western blot.