Proteomic analysis of organ‐specific post‐translational lysine‐acetylation and ‐methylation in mice by use of anti‐acetyllysine and ‐methyllysine mouse monoclonal antibodies

Post-translational lysine-acetylation and -methylation are two major PTMs of lysine residues in proteins. Recently, we established pan-reactive anti-acetyllysine mouse mAbs, which can bind to Nepsilon-acetylated lysine residues in various contexts of amino acid sequences. In the present study, we established pan-reactive anti-methyllysine mouse mAbs comparable to the anti-acetyllysine ones. By using these anti-acetyllysine and -methyllysine antibodies, we found that the pattern of lysine-acetylated and -methylated proteins in mouse organs showed extreme variation from organ to organ. We selected brain and skeletal muscle as model cases to be further analyzed by 2-DE followed by Western blotting. In brain, alpha-tubulin at its basal level was found to be extremely acetylated; and alpha-enolase was shown to be a newly recognized possibly acetylated protein. NF-L protein, Hsc70, alpha-tubulin fragments, beta-actin, and brain-type creatine kinase were identified as putative lysine-methylated proteins in mouse brain. In skeletal muscle, lysine-methylation of alpha-actin and both lysine-acetylation and -methylation of muscle-type creatine kinase were found as novel putative lysine-modified proteins. The approach presented here might be useful to find novel disease markers and/or drug target molecules that would not be noticed by use of the traditional proteomic approach only.