In Uniprot, proteomes are the set of all translated proteins from a genome assembly, and these can be used for protein analysis in different organisms. A reference proteome is the one that best represents a species, is of the best quality, or is a ‘landmark’ for that taxon. We have developed a novel workflow to select reference proteomes, which ensures that every species has at least one reference proteome, and recently the UniProt Knowledgebase (UniProtKB) exclusively started to consist of proteins from reference proteomes, supplemented by a small set of additional biologically important proteins. This webinar will explain the recent major changes in UniProtKB and how users can explore proteomes. At the end of the talk, there will be an opportunity for participants to ask questions.