Western blotting combines gel electrophoresis with use of a membrane to separate and identify target proteins using antibodies. Proteins are separated into bands using electrophoresis, and are then transferred to a membrane using filter-paper capillary action or an electroblotting technique. The effectiveness of the transfer can be checked by means of a stain – typically Ponceau S.
The membrane is then blocked from further protein interaction with diluted bovine serum albumin or non-fat milk solution. This ensures the antibodies bind only to the proteins, and not to the membrane substrate. False positives and fuzzy results are thus minimized, giving coherent and repeatable results.
The next stage is to incubate the membrane with a diluted primary antibody solution - typically 0.5 to 5.0 mcg/mL. The membrane is rinsed to remove any unbound protein, and exposed to a secondary...