PhosphoSitePlus provides comprehensive information and tools for the study of protein post-translational modifications (PTMs) including phosphorylation, acetylation, and more. The web use is free for everyone including commercial. PhosphoSitePlus is an open, dynamic, continuously curated, and highly interactive systems biology resource for studying experimentally observed PTMs in the regulation of biological processes. PhosphoSite® was limited to phosphorylation. PSP, while still providing comprehensive coverage of protein phosphorylation, now includes coverage of other commonly studied PTMs including acetylation, methylation, ubiquitination, and O-glycosylation.

PSP includes critical structural and functional information about the topology, biological function and regulatory significance of specific modification sites, and powerful tools for mining and interpreting this data in the context of biological regulation, diseases, tissues, subcellular localization, protein domains, sequences, motifs, etc.