This special edition on Quantitative Mass Spectrometry in Proteomics focuses on some of the leading technologies that are currently used in state-of-the-art laboratories. In recent years, mass spectrometry-based proteomics has come a long way and seen a tremendous advancement to the point where quantitative measurements are no longer a distant goal, but have become routine to some of the leading labs. However, this is not a simple achievement, since it requires an interdisciplinary effort, starting from experimental design, to adequate sample preparation, to state-of-the-art technology, to bioinformatics and statistical analyses. The advancements and possibilities in quantitative proteomics have, in turn, changed the way, biological research can be done. Rather than focusing on a single protein, more ambitious goals are pursued and entire networks of proteins or protein complexes are interrogated in current proteomics experiments. While there are other techniques available, this special edition focuses on metabolically, chemically or enzymatically introduced mass tags and the quantitative study of protein-ligand interactions. The paper by Graham et al. introduces the commonly used stable isotope labeling by amino acids in cell culture (SILAC) technology to biologists and covers a broad range of applications, bioinformatics tools and potential problems that should be considered when using this technology. Noirel et al. introduce the chemical labeling technique iTRAQ. In a meta-analysis of the the current iTRAQ literature, they give advice to researchers on experimental design, biological and technical replicates and data analysis tools. This is followed by a paper by Boja that specifically introduces the iTRAQ technology with high collision dissociation that has become available in present-day Orbitrap technologies. The review by Hajkova et al. covers the recent developments of the proteolytic 18O labeling technique to improve the reliablity of the label, the use of computational tools to quantify peptide and protein ratios, and a new strategy to compare a large number of samples. Finally, Sharon and Robinson describe how they use mass spectrometry to determine the composition, stoichiometry, subunit interactions, and architectural organization of non-covalent protein complexes. This issue is aimed at both mass spectrometry practitioners who want to familiarize themselves with the current state-of-theart as well as biologists who contemplate the pros and cons of the current proteomics technologies. We certainly hope that it will stimulate further research in the exciting area of quantitative mass spectrometry.
Current Proteomics research in the emerging field of proteomics is growing at an extremely rapid rate. The principal aim of Current Proteomics is to publish well-timed review articles in this fast-expanding area on topics relevant and significant to the development of proteomics. Current Proteomics is an essential journal for everyone involved in proteomics and related fields in both academia and industry.