Textbook-like illustrations aim to improve the graphical representation of higher-level pathways in the Reactome events hierarchy, e.g., “signal transduction”, “apoptosis”, or “metabolism of proteins” whose pathway diagrams consisted of green boxes labeled with the names of sub-events, optionally located in cellular compartments and connected by arrows. These green-box diagrams feature limited navigation: clicking on a green box takes the user to that sub-event.
There was a general agreement that green-box diagrams are not that appealing, and put off users accustomed to textbook-quality illustrations of biological processes with striking, intuitively clear iconography. The project includes generation of scalable vector graphic (SVG) versions of illustrations, and a diagram module that makes these images interactive by enabling actions such as hovering over the items or selecting them to show the associated content in the details panel.
Developing this project has also driven the creation of the Icon Library; a consistent iconography compendium that ranges from simple protein labels to representations of organelles, receptors and cell types. The library has now been integrated in the main search as well as in the pages of their associated entities such as proteins or chemicals. Icons can be found by their name, description, designer and/or contributor.
The Icon Library is freely accessible (under a CC-BY 4.0 licence) and it is suitable for a broad range of purposes, from schematic pathway sketches in scientific presentations and publications to grant proposal illustrations. As the library was created to be a community resource, the invitation for third parties to contribute is still open. Aiming to achieve technical and artistic consistency, detailed guidelines are provided at https://reactome.org/icon-info. To acknowledge the community engagement, each icon is attributed to the author through a metadata file linking to a portfolio and/or ORCID id. As of September 2018, the library has considerably grown to 1,150 components.
