Why do I see a second, larger band with my Histone H2A.X antibody?

Histones have numerous post-translational modifications (PTMs), which can cause the protein to run at a different rate during electrophoresis. The upper band that migrates at ~25-27 kDa is likely phosphorylated histone H2A.X which also contains additional PTMs, such as ubiquitination. We believe this to be the case as the signal of the phosphorylated histone H2A.X band at 15 kDa and the upper band at 25-27kDa both increase in signal strength upon UV treatment. In addition, the 25-27kDa upper band can be seen with our total histone H2A antibodies (#7631, #2595, #50722), in both untreated and treated samples, indicating that it is specific to histone H2A.

Last updated: February 27, 2024