•http://www.reactome.org/

Not so long ago, anything you needed to know about the molecular interactions that took place in living systems could be found between the covers of Molecular Biology of the Cell. Now, with thousands of proteins and other metabolites continually being described, biologists need access to a comprehensive, up-to-date and accessible representation of cellular pathways. Reactome — a curated online database of human biological pathways that was released on 2nd June, 2004 — has been created to fulfil that need.

Jointly funded by Cold Spring Harbor Laboratory and the EMBL (European Molecular Biology Laboratory) European Bioinformatics Institute (EBI), Reactome, a swanky reincarnation of The Genome Knowledgebase, provides a clear, integrated view of many core cellular pathways and reactions. Along with a description of the selected process — the mitotic cycle, say — is a diagram of the pathway and links through to all the molecules (not only human ones) known to participate in it. You can decide between viewing the entire process or any of its subcategories (the G1 phase, for example). The site is easy to navigate and the 'starry sky' representation of each molecular reaction highlights links between pathways.

Named experts contribute the information, which is peer-reviewed and cross-referenced to several literature and biological databases, including Gene Ontology (GO). The data are searchable, citable and free. Reactome is therefore more than just an online textbook and it aptly responds to the current desire for a 'systems biology' view of molecular life.

Releases will occur quarterly, and will probably include additional processes and an expansion of its repertoire of interactions to include intercellular pathways.