Figure 3.

Combination of metabolically and chemically labeled stable isotopes to increase the sample multiplexing capabilities using a triplex SILAC and 6-plex TMT simultaneously. (A) Metabolic labels provide intact mass differences distinguishable in an MS1 scan of intact peptide ions. Upon isolation and fragmentation of the light, medium, and heavy versions of a peptide, the isobaric labels provide separate multiplexed quantitative measurements for each in the MS/MS spectra. (B) Structure of the novel TMT tags. Reproduced with permission from ref 37. Copyright 2012 American Association for the Advancement of Science.