STRING is a database of known and predicted protein interactions.
The interactions include direct (physical) and indirect (functional) associations; they are derived from four sources:
- Genomic Context
- High-throughput Experiments
- (Conserved) Coexpression
- Previous Knowledge
STRING quantitatively integrates interaction data from these sources for a large number of organisms, and transfers information between these organisms where applicable.
Further information about the STRING API can be found in the help section.
There are 2 sister projects that built on STRING data, namely STITCH (http://stitch.embl.de/) and eggNOG (http://eggnog.embl.de/version_4.0.beta/).