Quantifying small molecule-induced changes in cellular protein expression and posttranslational modifications using isobaric mass tags.

Proteomics enables the comprehensive analysis of cellular perturbations induced by bioactive small molecules and contributes to our understanding of the mechanisms by which drugs elicit their activity in disease situations. Here we describe a quantitative proteomics approach to study dose-dependent changes in protein expression and posttranslational protein modifications in human promyelocytic leukemia cells in response to inhibition of histone deacetylases by Vorinostat. The method employs isobaric mass tags (tandem mass tags, TMT) to enable the multiplexed quantitative analysis of up to six samples and antibodies directed against acetylated lysine residues for immunoenrichment of TMT-encoded acetylated peptides.