Matthias Mann, Director at the MPI of Biochemistry, has developed a mass spectrometric method to rapidly analyze the protein content of a cell. To this end, Mann and his team in the department “Proteomics and Signal Transduction” developed a special Electrospray procedure to separate the respective protein molecules. These developments have led to the first identification and quantification of the proteome in yeast (about 4400 proteins), which is an important model system.