Figure 7. The ubiquitin remnant profiling technique for proteome-wide profiling of ubiquitination sites.

Proteins extracted from cell lysates or tissues are digested with trypsin. The ubiquitin remnant-containing peptides are immunoprecipitated using anti-diglycyl lysine antibodies and analyzed by tandem MS. The presence of the diglycine remnant on lysine residues can be identified by the 114.04 Da change in the monoisotopic mass between the modified and non-modified y-ions or b-ions.