Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting analyses via colored stacking gels

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is a standard method for protein analysis. However, the stacking gel employed for the standard SDS-PAGE is transparent and indistinct. Therefore, loading samples into stacking gel wells can be challenging. Accordingly, an acidic dye (tartrazine, brilliant blue FCF, or new coccine), which allowed easy visualization of the stacking gel wells and straightforward sample loading into these wells, was added to the SDS-PAGE stacking gel to resolve this issue. Moreover, the performance of these gels was comparable to that of non-colored standard gels. Thus, researchers worldwide could adopt this simple method for protein analysis.