ST6GAL1 and nephritis: Notably, the protein expression level of the alpha2,6-sialyltransferase 1 (St6gal1), which is responsible for terminal sialylation of IgG Fc glycan (24, 29–31), was reduced in total and IgG-switched PCs (IgG+PC) of Fcgr2b−/− mice with nephritis, but not in PCs of 56R+/−Fcgr2b−/− mice (Figures 3E,F).