[Dictionary] Reactome

A free, open-access, manually curated database of human biological pathways, built on a reaction-based data model: the core unit is a single reaction, and entities (proteins, complexes, nucleic acids, small molecules) participating in that reaction connect into a network of reactions that together form a pathway. Content is authored by PhD-level biologists and passes a structured peer-review process before publication -- a pathway is not 'in Reactome' merely because a contributor drafted it, but only once it has cleared that editorial review. Maintained collaboratively by teams at OICR, OHSU, EMBL-EBI, and NYULMC; equivalent pathways in other species are generated computationally by orthology projection from the curated human data rather than curated independently for each organism; updated quarterly; exportable in BioPAX, SBML, Neo4j graph, and other standard formats.