The Interplay of Proteins
Unlike the genetic blueprint (genome), the protein equipment (proteome) of an organism is not the same for all cells. Even in one and the same cell, it changes very fast. Matthias Mann and his research department want to find out which proteins exist in a cell at a certain point of time.
Every cell type has its specific protein equipment. It changes continuously because proteins are formed, modified or degraded. But when are these proteins generated? This depends on the genes active at that point of time. They contain the information about the proteins that have to be produced. But not all modifications of proteins are visible on the genetic level: Many changes take place after the production of the protein, for example by the addition of a phosphate or an acetyl group. Matthias Mann and his colleagues discovered that such modifications have an influence on all areas of life of the cell. They now use this knowledge to investigate diseases such as cancer.
Protein equipment of cancer cells decoded
The scientists developed SILAC, a method to quantitatively compare different cell phases and thus analyze the interplay of the proteins. Cells are “fed” with labeled amino acids, which they integrate into their proteins. A comparison with “unlabeled” cells shows changes and modifications. In doing so, Mann was able to identify more than 10,000 proteins of cancer cells and could demonstrate how they change over time.
Switching from an ordinary car to a race car
During mass spectrometry, protein samples are positively charged via electro spray and then pulled through an electric field. Afterwards, the mass spectrometer separates the components according to their size and charge. Using MaxQuant, a software developed in the department, the scientists are able to interpret and to analyze the protein components much faster and more accurately than with previous methods.