NCBI Biosystems (www.ncbi.nlm.nih.gov/biosystems/) is a new database within Entrez that collects together molecules that interact in a biological system, such as a biochemical pathway or disease. Currently, Biosystems receives data from two sources: the Kyoto Encyclopedia of Genes and Genomes (2–4) and the EcoCyc subset of the BioCyc database (5). These source databases provide diagrams of pathways that display the various components with their substrates and products, as well as links to relevant literature. In addition to being linked to such literature in PubMed, each component within a Biosystem record is also linked to the corresponding records in Entrez Gene and Protein, while the substrates and products are linked to records in PubChem (see below) so that the Biosystem record centralizes NCBI data related to the pathway, greatly facilitating computation on such systems.
