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 Nϵ‐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, α‐tubulin at its basal level was found to be extremely acetylated; and α‐enolase was shown to be a newly recognized possibly acetylated protein. NF‐L protein, Hsc70, α‐tubulin fragments, β‐actin, and brain‐type creatine kinase were identified as putative lysine‐methylated proteins in mouse brain. In skeletal muscle, lysine‐methylation of α‐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.