Figures & data
Figure 1. (A) Schematic illustration of the mucin-type O-glycan biosynthesis pathway. Tn and sialyl Tn represent the galactose-deficient O-glycans. GalNAc-T: polypeptide N-acetylgalactosaminyltransferases; C1GalT1: core 1 β1,3-galactosyltransferase; ST6GalNAc-III/IV: α2,6-sialyltransferase III/IV; ST3Gal-I: α2,3-sialyltransferase I; ST6GalNAc-I/II: α2,6-sialyltransferase I/II. Cosmc: core 1 galT1-specific molecular chaperone, required for proper activity of human C1GalT1. (B) IgA1 hinge region. The potential O-glycosylation sites are boxed. (C) In planta generation of sialyl Tn structures on the IgA1 hinge region. Human IgA1 was transiently co-expressed with GCSI-GalNAc-T2, GCSI-ST6GalNAc-II and other proteins required for sialylation in N. benthamiana. Recombinant IgA1 was purified from leaves, digested with trypsin and analyzed by LC-ESI-MS/MS. The highlighted peaks in the mass spectrum indicate the presence of sialyl Tn and Tn O-glycans on the peptide containing the IgA1 hinge region. Details of protein expression, purification and glycopeptide analysis were described previously.Citation8
