Résumé
A good loading control is critical for accurate comparison of tissue protein levels in aged and young tissue. After reviewing the literature we discovered that the housekeeping proteins commonly used in Western analysis had significant drawbacks. The purpose of this study was to evaluate the linearity and reproducibility of common housekeeping proteins tubulin, actin and GAPDH compared to measures of total protein staining using Direct Blue and Stain Free gels. We found that measurements of total protein staining were superior to housekeeping proteins both in linearity and reproducibility in young and old mouse, liver, heart, and brain. Among the total protein staining methods, the Stain Free method was superior to Direct Blue, in terms of lower variability and higher accuracy in all tissues, at both ages.