ABSTRACT
O Stable Isotope Coding Using Proteolysis ........... 267 13.3 Analysis and Quantification of Post-Translational Modifications Using
Isotope Coding ............................................................................................. 268 13.3.1 Phosphorylation................................................................................ 269 13.3.2 Glycosylation ................................................................................... 273
13.4 Absolute Quantification Using Internal Stable Isotope-Coded Standards..... 275 13.5 Isobaric Tags for Absolute and Relative Quantification.............................. 276 13.6 Conclusion.................................................................................................... 277 13.7 Future Prospects........................................................................................... 278 Acknowledgments.................................................................................................. 278 References.............................................................................................................. 279
Proteome analysis has increasingly relied on mass spectrometry (MS) to identify and elucidate protein function because it is has proven to be an effective and versatile analytical tool for protein characterization. In addition to detecting and enumerating the proteins expressed in an organism, the quantification of differences in the protein profiles of cells, tissues, or body fluids of different origins or states is increasingly being recognized as a key objective of mass spectrometry-based proteomics research. Such differential analysis of protein expression provides a more accurate and comprehensive view of the dynamic changes that occur within a cell under different conditions, as compared to mRNA expression analysis using cDNA microarrays. This is because regulation of protein expression is not solely dependent upon regulation of the expression of genes coding for that protein, but also involves a number of post-translational modifications (PTMs) that play a more decisive role in cellular regulation.
