Quantitative Mass Spectrometry: Elucidation of the Transduction Cascade Triggered by B cell Receptors

Mass Spectrometry and Proteomics The above definition presents a challenge to modern mass spectrometry, as the proteome of a cell is not constant, but rather is regulated dynamically. For example, different proteins with different numbers of copies are present during the different stages of cell development, differentiation and proliferation, as well as in the individual subcellular processes. Bioanalytical mass spectrometry allows the fast and reliable identification and quantification of proteins as well as the analysis of protein modifications. The development of so-called soft ionisation methods, such as Matrix-Assisted Laser/Desorption Ionisation (MALDI) and Electrospray Ionisation (ESI), has made possible the ionisation of entire proteins and protein fragments (termed peptides) in the gas phase. The increasing number of sequenced genomes provides in silico information about the molecular weight and the amino acid sequence of proteins and in this way allows comparison with the masses obtained by mass-spectrometry measurements.