b'Protein quantitationWe offer reagents and kits for both discovery and targeted proteomics applications (Table 1). Discovery proteomics utilizes techniques such as SILAC and isobaric mass tagging that allow the user to look at global protein expression levels. In contrast, targeted proteomics utilizes selected or multiple reaction monitoring (SRM/MRM), which are methods of absolute quantitation (also termed AQUA), in which a complex sample is spiked with a stable isotope-labeled peptide that acts as internal standard for a specific subset of proteins.Table 1. Choose the right protein quantitation reagent for mass spectrometry.SureQuant SILAC TMT TMTpro Peptides for SRM targeted assaysApplication type Discovery quantitation Targeted quantitationAmine-, cysteine-,Amine-reactive Labeling method Metabolic and carbonyl- mass tags Spike-in standard Spike-in standardreactive mass tagsCulturedCulturedCulturedCultured Sample type Culturedmammalian cells; mammalian cells; mammalian cells; mammalian cells;mammalian cells tissue; tissue; tissue; tissue;biofluids biofluids biofluids biofluidsDigestion protocol In-gel In solution In solution In solution In solutionMS 2(6-plex) 3Quantitation mode MS 1 MS 3(10-plex) MS 3(16-plex) MS 1 MS 1MS 3(11-plex) MS(18-plex)Multiplex options 2-plex, 3-plex,2-plex, 6-plex,16-plex, 18-plex Samples notSamples not 4-plex 10-plex, 11-plex combined combinedMass spectrometry thermofisher.com/proteinbiology 89'