Organellar Proteomics: Tissue Specificity, Absolute Quantity, PosttranslationalModifications and Protein-Protein Interactions

Organellar proteomics combines subcellular fractionation and mass spectrometry-based protein identifications. In the past decades, organellar proteomic analysis has been carried out for virtually every subcellular compartment in mammalian cells and tissues [1-4]. While conventional biochemical and biophysical approaches study the structures and functions of individual proteins, mass spectrometrybased proteomic studies allow us to understand the entire proteome or sub proteome systematically by: (i) Identifying proteins present in each subcellular organelle; (ii) Quantifying their expression levels; and (iii) Characterizing their posttranslational modifications and proteinprotein interactions. All of the above determines the protein’s function and activity.