BitterDB: 2024 update on bitter ligands and taste receptors.

BitterDB (http://bitterdb.agri.huji.ac.il) was introduced in 2012 as a central resource for information on bitter-tasting molecules and their receptors, and was updated in 2019. The information in BitterDB is used for tasks such as exploring the bitter chemical space, choosing suitable ligands for experimental studies, analyzing receptors' selectivity and promiscuity, and developing machine learning predictors for taste. Here, we describe a major upgrade of the database, including significant increase in content as well as new features. BitterDB now holds over 2200 bitter molecules. For ∼700 molecules, at least one associated bitter taste receptor (TAS2R) is reported. The overall number of ligand-TAS2R associations is now close to 1800. BitterDB is extended to a total of 66 species (including dog, birds, fishes and primates). Following advances in computational structure prediction by AlphaFold and related methods, and the experimental determination of TAS2R structures by cryo-electron microscopy, BitterDB provides links to available structures of TAS2Rs.