Labeling strategies in mass spectrometry-based protein quantitation.

Mass spectrometry-based techniques for relative and absolute protein quantitation have advanced greatly over the past decade. New measurement strategies and improvements to existing methodologies have expanded the utility of mass spectrometry-based characterization of protein expression profiles, in particular by targeting a diverse array of chemical functionality (e.g. post-translational modifications, specific amino acid residues, etc.) by selective stable isotope incorporation. This article focuses on current trends in stable isotope labeling for protein quantitation using enzymatic, metabolic, and chemical derivatization techniques. Furthermore, new advances in phosphoproteomic labeling and lanthanide-based labeling methods are described.