Quantitative analysis of complex protein mixtures using isotope-coded
affinity tags
Steven P. Gygi1, 4, Beate Rist1, 4, Scott A. Gerber2, Frantisek Turecek2, Michael H. Gelb2, 3
& Ruedi Aebersold1
1
Department of Molecular Biotechnology, University of
Washington, Box 357730, Seattle WA
98195-7730.
2
Department of Chemistry, University of Washington,
Box 357730, Seattle WA 98195-7730.
3
Department of Biochemistry, University of Washington
, Box 357730, Seattle WA
98195-7730.
4
These two authors contributed equally to this work.
Correspondence should be addressed to Ruedi Aebersold ruedi@u.washington.edugene expressionfunctional genomicsproteomicsprotein profilingmass spectrometry
We describe an approach for the accurate quantification and concurrent
sequence identification of the individual proteins within complex mixtures.
The method is based on a class of new chemical reagents termed isotope-coded
affinity tags (ICATs) and tandem mass spectrometry. Using this strategy, we
compared protein expression in the yeast Saccharomyces cerevisiae,
using either ethanol or galactose as a carbon source. The measured differences
in protein expression correlated with known yeast metabolic function under
glucose-repressed conditions. The method is redundant if multiple cysteinyl
residues are present, and the relative quantification is highly accurate because
it is based on stable isotope dilution techniques. The ICAT approach should
provide a widely applicable means to compare quantitatively global protein
expression in cells and tissues.
