Isobaric tagging for relative and

Isobaric tags for relative and absolute quantitation of proteins in proteomic research Janus kinase c-Jun iV-terminal kinase... 

The technique of isobaric tag for relative and absolute quantification (iTRAQ) is based on covalently labeling the amines at N-termini and the side chains of peptides with isotope-coded tags after the proteins have been isolated form biological systems, denatured, and enzymatically digested. Here the isotope labeling is carried out at a much later stage than in both SILAC and ICAT. iTRAQ is an MS/MS technique that uses CID-derived ions for both the identification and quantification of proteins. 

Some popular quantitative methods in proteomics are based on derivatization with agents containing a stable isotope. In this respect, isotope-coded affinity tags (ICAT) have been widely used [121], as have isobaric tags for relative and absolute quantitation (iTRAQ) [122]. 

Isobaric Tags for Relative and Absolute Quantitation represents recent technology advancement, where four specific reagents label peptides in up to four samples. While the labeled peptides have the same mass, each label fragments into a different sized, characteristic tag that can be identified, and quantified in the tandem mass spectra In Arabidopsis iTRAQ has been used to map the organellarproteomes [123]. Another study applied iTRAQ to describe early changes to the phosphoproteome oiArabidopsis during defense response [124]. 

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