Fig. 4.
Validation of the K114 methylated site on protein CDC5Lfrom K562 cells. A, The tandem mass spectrum of the synthetic propionyl-methylated peptide LANTQGKpr+me1KprAKprR (bottom) showed a pattern that was almost identical to the pattern derived from its in vivo counterpart from K562 cells (top). B, Tandem mass spectra of in vivo-derived peptide LANTQGKme1K (top) and its synthetic counterpart peptide (bottom). Some y-ions and b-ions have a 4-Da difference between the in vivo-derived and synthetic peptides because of the isotopic labeling.