The Isotope-Coded Affinity Tag Method for Quantitative Protein Profile Comparison and Relative Quantitation of Cysteine Redox Modifications

What is it about?

The isotope‐coded affinity tag (ICAT) technique has been applied to measure pairwise changes in protein expression through differential stable isotopic labeling of proteins or peptides followed by identification and quantification using a mass spectrometer.

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Why is it important?

Changes in protein expression are observed when the identical peptide from each of two biological conditions is identified and a difference is detected in the measurements comparing the peptide labeled with the heavy isotope to the one with a normal isotopic distribution. This approach allows the simultaneous comparison of the expression of many proteins between two different biological states (e.g., yeast grown on galactose versus glucose, or normal versus cancer cells). Due to the cysteine‐specificity of the ICAT reagents, the ICAT technique has also been applied to perform relative quantitation of cysteine redox modifications such as oxidation and nitrosylation.

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