derives from ubiquitination signature dipeptidyl lysine 114.04293060302734375 114.09999847412109375 242.1378936767578125 242.279998779296875 A protein modification that crosslinks the N6-amino of a peptidyl lysine with the carboxyl of glycylglycine, the two glycine residues left after tryptic digestion of ubiquitin. C 10 H 18 N 4 O 3 C 4 H 6 N 2 O 2 GlyGly K MOD:00492 N6-(glycylglycyl)lysine N6-glycylglycyl-L-lysine PSI-MOD Unimod:121 artifact glyglyk ubiquitinylation residue ubiquitinylated lysine N6-acylated L-lysine crosslinked glycine residue crosslinked L-lysine residue