TMTiTRAQ

TMTiTRAQ is a term occasionally used to describe an integrated or hybrid approach that draws on the principles of two major isobaric labeling strategies in quantitative proteomics: Tandem Mass Tags (TMT) and isobaric tags for relative and absolute quantitation (iTRAQ). It is not a standardized or universally adopted technique, and in practice the phrase often denotes experimental designs that combine elements of TMT- and iTRAQ-based workflows rather than a single, widely validated method.

Background and principle

Both TMT and iTRAQ reagents label peptides at primary amine groups, producing isobaric labeled species that appear as a single peak in MS1. Upon tandem mass spectrometry (MS/MS or MS3), reporter ions are released whose intensities reflect relative peptide abundance across samples. TMT variants generally offer higher multiplexing potential (for example, 10-plex or 16-plex with TMTpro) compared with traditional iTRAQ (commonly 4-plex or 8-plex). A supposed TMTiTRAQ approach would rely on the same isobaric-labeling concept to enable multiplexed quantification across multiple samples, potentially through a design that leverages both tag families within a study.

Applications and considerations

The intended applications mirror those of standard isobaric labeling workflows: large-scale quantitative proteomics, including comparative proteome profiling, phosphoproteomics, and cross-condition analyses. However, combining TMT and iTRAQ within a single experiment is not a routine practice due to differing chemistries, reporter-ion masses, and data-processing considerations. In such proposals, careful experimental design and cross-normalization are required, and data analysis must account for potential inter-tag variability and interference. Cost and instrument requirements, such as high-resolution MS and appropriate MS3 strategies to mitigate ratio compression, remain factors.

See also

Tandem Mass Tags (TMT), isobaric tags for relative and absolute quantitation (iTRAQ), quantitative proteomics, mass spectrometry.