Thousands of experiments focusing on the dynamics of single proteins and their closest interacting partners have provided valuable but fragmented views of the cell. Meanwhile, quantitative proteomics continues to build increasingly comprehensive but static inventories. To get a complete picture of the cell, one needs to characterize the dynamics and interactions of the entire proteome.
To address this, Matthias Mann of the Max Planck Institute for Biochemistry in Germany developed a method that combines large-scale quantitative proteomics with a technique for time-labeling cell cultures. First used to deduce tyrosine phosphorylation in growth factor signaling1 and later to describe the activity of a cellular substructure, the nucleolus,2 the method has helped map the in vivo phosphoproteome3 as well as the network of interactions in the nucleolus.4 Used in conjunction with traditional microscopy, it is providing a more complete view of the dramatic changes in protein composition in response to metabolic stimuli. ...
