Erasable Western Blots

Western blotting (reviewed in 1-3; see also this vol., Chapter 24 ) refers to formation and detection of an antibody-antigen complex between an antibody and a polypeptide that is immobilized on derivatized paper. Most commonly, polypeptides in a complex mixture are separated by electrophoresis through polyacrylamide gels in the presence of sodium dodecylsulfate (SDS), electrophoretically transferred to thin sheets of nitrocellulose or nylon, and reacted sequentially with one or more antibody-containing solutions. This sequence of manipulations can be utilized to determine whether a polypeptide recognized by a specific antiserum is present in a particular biological sample (cell type, subcellular fraction, or biological fluid), to follow the purification of the polypeptide, or to assess the location of epitopes within the polypeptide during chemical or enzymatic degradation. Alternatively, the same series of manipulations can be utilized to determine whether antibodies that recognize a particular polypeptide are detectable in a sample of biological fluid. Since Western blotting takes advantage of the power of electrophoresis for separating complex mixtures of polypeptides, it is possible to derive large amounts of information from this technique without necessarily purifying the antigen being studied.