Approaches for systematic proteome exploration

With the completion of the human genome project (HUGO) during recent years, gene function, protein abundance and expression patterns in tissues and cell types have emerged as central areas for the scientific community. A mapped human proteome will extend the value of the genome sequence and large-scale efforts aiming at elucidating protein localization, abundance and function are invaluable for biomarker and drug discovery. This research area, termed proteomics, is more demanding than any genome sequencing effort and to perform this on a wide scale is a highly diverse task. Therefore, the proteomics field employs a range of methods to examine different aspects of proteomics including protein localization, protein–protein interactions, posttranslational modifications and alteration of protein composition (e.g. differential expression) in tissues and body fluids. Here, some of the most commonly used methods, including chromatographic separations together with mass spectrometry and a number of affinity proteomics concepts are discussed and exemplified.