Fig. 3.

 A deep proteomic workflow of TMT-LC/LC-MS/MS. The 16-plex TMT reagents are represented by different colors, which react with amine groups at peptide N-termini and lysine residues. In addition to the amine-reactive group, the isobaric TMT reagents also contain a reporter ion group and a balance group. The mass difference in the reporter group is offset by the balance group, enabling isobaric labeling and pooling. The pooled peptides are fractionated by LC/LC, and identified as mixed, isobaric precursor ions. After fragmentation, the TMT tags are cleaved between the reporter and balance groups, generating reporter ions for quantification