O-GlcNAcAtlas 4.0: An Updated Protein O-GlcNAcylation Database with Site-specific Quantification.

O-linked β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) is a monosaccharide modification on proteins predominantly inside cells. It is widely appreciated that spatiotemporal protein O-GlcNAcylation regulates a plethora of biological processes. High-throughput analytical techniques, particularly site-specific O-GlcNAc proteomics, have tremendously advanced the profiling of O-GlcNAc proteomes. Recently we established O-GlcNAcAtlas, a highly curated database of O-GlcNAc proteins/peptides/sites from experiments reported in the past forty years. However, a resource for O-GlcNAcylation quantification information is not available yet. Herein, we provide an updated database O-GlcNAcAtlas 4.0 by incorporating information of O-GlcNAcylation quantification. Exhaustive curation of published literature yielded a total of about 5,400 quantification events for 3,130 unique O-GlcNAc sites. The quantification vales were then systematically integrated with the specific O-GlcNAc sites and catalogued in O-GlcNAcAtlas, with key experimental details (including sample sources, conditions and methods) presented. Taken together, we present O-GlcNAcAtlas 4.0, a unique database hosting qualitative and quantitative data of O-GlcNAcylation on proteins. As a comprehensive repository supplemented with protein O-GlcNAcylation dynamics, the updated database will further facilitate related functional investigations by the biomedical community. O-GlcNAcAtlas 4.0 is freely accessible at https://oglcnac.org/atlas/.