The STRING database in 2021: customizable protein–protein networks, and functional characterization of user-uploaded gene/measurement sets

This update paper describes the STRING database, which aims to integrate all known and predicted associations between proteins, including both physical interactions and broader functional associations that are prized for their versatility, specificity, and adaptability. To achieve this, STRING collects and scores evidence from several sources: automated text-mining of the scientific literature, databases of interaction experiments and annotated complexes and pathways, computational interaction predictions from co-expression and from conserved genomic context, and systematic transfers of interaction evidence from one organism to another.

STRING aims for wide coverage, with the upcoming version 11.5 containing more than 14,000 organisms. The authors describe changes to the text-mining system, a new scoring mode for physical interactions, and extensive user-interface features for customizing, extending, and sharing protein networks. They also explain how to query STRING with genome-wide experimental data, including automated detection of enriched functionalities and potential biases in the user's query data, broadening the resource's usefulness for interpreting high-throughput measurements.