Fig. 1: The overall architecture of the human KOGG complex.

a Multi-functions of Purified LH3-ColGalT1 Complex. Left: 2-OG-dependent oxygenase activities of the purified KOGG complex. Oxygenase activities were minimal upon the removal of 2-OG from the reaction mixtures and substantially reduced in the absence of the KOGG complex sample, Fe²⁺, or substrate peptide. Middle: Galactosyltransferase activities of the purified KOGG complex. The galactosyltransferase activities were minimal upon the removal of UDP-galactose from the reaction mixtures and substantially reduced in the absence of the KOGG complex sample, Mn²⁺, or substrate peptide, as well as the necessary reaction components of 2-OG-dependent oxygenase activities, i.e., 2-OG and Fe²⁺. Right: Glucosyltransferase activities of the purified KOGG complex. The glucosyltransferase activities were minimal upon the removal of UDP-glucose from the reaction mixtures and also substantially reduced in the absence of the KOGG complex sample, Mn²⁺, or substrate peptide, as well as the necessary reaction components of 2-OG-dependent oxygenase activities, i.e. 2-OG and Fe²⁺, and the necessary reaction components of galactosyltransferase activities, UDP-galactose. (n = 3 biologically independent samples). Data are presented as mean values +/− SD. Source data are provided as a Source Data file. Data analysis was performed using one-way ANOVA with Dunnett’s multiple comparisons test. **, P-value < 0.01; ***, P-value < 0.001; ****, P-value < 0.0001. b Cryo-EM map of the heterotetrametic complex of human LH3 and ColGalT1. The cryo-EM density map of the human KOGG/UDP-Gal complex was viewed from two angles. The cryo-EM density map is colored in light red/red for LH3^A/B, cyan/blue for ColGalT1^U/V and magenta for glycosyl modifications. c Molecular model of the KOGG complex. KOGG/UDP-Gal complex was depicted as a cartoon model, colored by protomers according to the corresponding cryo-EM maps shown above. d Structural analysis on LH3 (left) and ColGalT1 (right). The structure of LH3^B and ColGalT1^V, indicated by the frames in the complex model above, are depicted as a cartoon model, colored by domains to the schemes shown below.