In Western blotting, proteins are separated by their size using which technique?

In Western blotting, proteins are separated by their size utilizing gel electrophoresis. This technique involves the application of an electric field to a gel matrix, typically made of polyacrylamide. As the proteins migrate through the gel, smaller proteins move more easily and thus travel further than larger ones. This size-based separation is crucial for the subsequent analysis in the Western blotting process, where specific proteins are identified using antibodies.

Using gel electrophoresis allows researchers to assess protein expression levels, post-translational modifications, and protein interactions through size separation, making it a foundational step in the Western blotting technique. The combination of size and the use of antibodies for detection enables accurate characterization of proteins within a sample.