Protein O-GlcNAc transferase

Protein O-GlcNAc transferase
National Center for Biotechnology Information, U.S. National Library of Medicine · Public domain · source
Name	Protein O-GlcNAc transferase
Organism	Human
Length	~1036 aa (isoforms vary)
Location	Nucleus, cytoplasm, mitochondria, centrosome
Function	Post-translational modification enzyme

Protein O-GlcNAc transferase is a nucleocytoplasmic enzyme that catalyzes the addition of O-linked N-acetylglucosamine to serine and threonine residues on nuclear and cytoplasmic proteins. Discovered through biochemical studies in mammalian cell extracts and later cloned, the enzyme has become central to research in cell signaling, transcriptional regulation, metabolism, and neurobiology. OGT links nutrient sensing to proteome function and is implicated in diverse processes studied across laboratories, institutes, and clinical centers.

Function and Biological Roles

OGT mediates dynamic post-translational modification by transferring N-acetylglucosamine from UDP-GlcNAc to protein substrates, a role revealed in collaborations among groups at Harvard University, Massachusetts Institute of Technology, University of Cambridge, Stanford University, and University of California, San Francisco. In chromatin regulation, OGT modifies histone-associated factors characterized at Cold Spring Harbor Laboratory and Max Planck Society facilities, influencing transcriptional networks investigated in models at Johns Hopkins University and University of Oxford. OGT activity integrates signals from nutrient pathways explored at Yale University and University of Toronto, linking hexosamine biosynthetic pathway effectors described by teams at University of Pennsylvania and Imperial College London. In neurobiology, OGT-dependent modulation of synaptic proteins has been pursued at Massachusetts General Hospital, Salk Institute, and Rockefeller University. Cellular stress responses involving OGT were characterized in studies at National Institutes of Health, European Molecular Biology Laboratory, and Institut Pasteur.

Structure and Mechanism

Structural characterization of OGT involved X-ray crystallography and cryo-EM performed by consortia including researchers from University of California, Berkeley, University of Oxford, ETH Zurich, Riken, and European Synchrotron Radiation Facility. The enzyme contains N-terminal tetratricopeptide repeat (TPR) arrays and a C-terminal catalytic glycosyltransferase domain, with domain architecture compared to glycosyltransferases studied at Max Planck Institute for Molecular Physiology and Cold Spring Harbor Laboratory. Mechanistic studies reference catalytic residues identified in mutational screens by groups at University of Chicago and University of Michigan and kinetic analyses from labs at University of California, San Diego and Duke University. Co-crystal structures with UDP-GlcNAc and peptide substrates were reported in collaborations involving MRC Laboratory of Molecular Biology and University of Edinburgh, informing transition-state models akin to those developed at Weizmann Institute of Science and Seoul National University.

Regulation and Interactions

OGT is regulated transcriptionally and post-translationally; regulatory networks have been mapped by consortia including teams at Broad Institute, Wellcome Sanger Institute, EMBL-EBI, and European Bioinformatics Institute. Interacting partners include chromatin remodelers and transcription factors characterized in studies at Columbia University, University of California, Los Angeles, and Princeton University. Signaling crosstalk between OGT and kinases was elucidated by researchers at Cold Spring Harbor Laboratory, Fred Hutchinson Cancer Research Center, and University of Wisconsin–Madison. Mitochondrial targeting and adaptor interactions were studied at University of Tokyo and Karolinska Institutet. Regulation by nutrient-sensitive UDP-GlcNAc pools involves enzymes in the hexosamine pathway characterized at University of Illinois, University of Colorado, and University of Basel.

Substrate Specificity and Targets

OGT modifies a wide array of substrates spanning transcription factors, splicing regulators, cytoskeletal proteins, and signaling molecules, with substrate catalogs generated by proteomics groups at Stanford University, Broad Institute, Max Planck Institute for Biochemistry, and European Molecular Biology Laboratory. Notable substrates investigated include components of the transcriptional machinery studied at Rockefeller University and University of Cambridge, and synaptic proteins analyzed at Salk Institute and University College London. Mass spectrometry-based target identification was advanced by teams at University of Washington, University of Toronto, ETH Zurich, and University of Copenhagen. Substrate selection determinants were explored through peptide library screens at Massachusetts Institute of Technology and computational predictors developed at Carnegie Mellon University.

Physiological and Pathological Implications

OGT function impacts development, metabolism, and neurodegeneration; mouse genetic models were developed at Jackson Laboratory, The Scripps Research Institute, and University of California, Davis. Dysregulation of OGT is linked to insulin resistance and diabetes studied at Joslin Diabetes Center and University of Oxford; cancer-associated roles were reported from research at MD Anderson Cancer Center, Memorial Sloan Kettering Cancer Center, and University College London. In neurodegenerative disease contexts, OGT alterations have been examined at Alzheimer's Disease Research Center sites, Harvard Medical School, and University of Pennsylvania Perelman School of Medicine. OGT’s involvement in cardiovascular physiology was described by investigators at Cleveland Clinic and Mayo Clinic. Therapeutic interest has driven small-molecule inhibitor development pursued by teams at Novartis, GlaxoSmithKline, Pfizer, and academic drug-discovery centers like Broad Institute.

Genetic and Evolutionary Aspects

OGT orthologs are conserved across metazoans and present in protists and plants, with comparative genomics performed by groups at Ensembl, NCBI, UCSC Genome Browser, and GenBank. Evolutionary analyses referencing datasets curated by 1000 Genomes Project and Genome Aggregation Database trace sequence conservation and domain evolution studied by research teams at Max Planck Institute for Evolutionary Anthropology and Wellcome Sanger Institute. Human genetic studies linking OGT variants to phenotypes were conducted in cohorts analyzed at UK Biobank, Framingham Heart Study, and ClinVar-linked clinical genetics centers. Model organism genetics employing Drosophila melanogaster, Mus musculus, Caenorhabditis elegans, and Arabidopsis thaliana provided functional insights.

Experimental Methods and Assays

Experimental approaches to study OGT include enzymatic assays, structural biology, proteomics, and cellular imaging developed at Mass Spectrometry Core Facilities affiliated with Broad Institute, EMBL, and University of California, San Diego. In vitro glycosylation assays using recombinant OGT were standardized in protocols from Addgene and methodological papers from Nature Methods and Journal of Biological Chemistry laboratories. Mass spectrometry workflows for O-GlcNAc peptide enrichment were refined by groups at Proteome Center Dresden and Scripps Research, while live-cell imaging and proximity labeling approaches were deployed by teams at Stanford University and Max Planck Institute for Biophysical Chemistry. Genetic perturbation methods including CRISPR screens and conditional knockouts were applied in studies at Broad Institute, University of California, Berkeley, and Whitehead Institute.

Category:Enzymes