Fig. 1: Cryo-EM structures of human OGT and OGT–OGA complex.

a The dynamic protein O-GlcNAcylation cycle mediated by OGT and OGA. b Domains and motifs of human OGT and OGA. TPR, tetratricopeptide repeat. c Human HEK293 cells with the endogenous OGT locus tagged with the HaloTag were treated with the HaloPROTAC3 compound for different duration times. Total cell lysates were blotted with the indicated antibodies. The experiment was repeated thrice with similar results. d Cryo-EM map of human OGT dimer (left panel) and the structure of the OGT dimer fitted into the EM map (right panel). GTD, glycosyltransferase family B domain. e Close-up views of the OGT dimerization interface. f O-GlcNAcylation of recombinant TAB1 by OGT WT or its monomeric 4A mutant in the presence of UDP-GlcNAc. The relative O-GlcNAc levels were quantified and indicated below. The experiment was repeated thrice with similar results. g Cryo-EM map of human OGT-OGA complex (left panel) and the structure of the OGT-OGA complex fitted into the EM map. GHD, glycoside hydrolase domain; IDR, intrinsically disordered region. h Superimposition of the structures of the OGT-OGA complex and the OGT dimer (colored in gray and with only one protomer shown). i Cryo-EM density of the UDP and NAG in OGT-OGA complex. Source data are provided as a Source Data file.