About half of all cellular proteins assemble either permanently
or transiently with other proteins into protein complexes.
We will provide an overview on experimental methods for
detecting such interactions and then introduce bioinformatics
methods for mining such interaction networks.
Importantly, interacting proteins are likely to share common
functions and are likely to be co-expressed. Thus, knowledge on
interaction partners is useful for annotating functions of
unknown proteins and to infer regulatory mechanisms.
Turned around, transcription factors often function in
combination with other transcription factors and partner
proteins to turn on/off expression of their target genes.
In summary, considering the complex protein interactome
helps in identification of functional and regulatory modules
in cells.