Nat. Rev. Rheumatol. doi:10.1038/nrrheum.2017.146 Figure 1 Effects of IgG glycosylation on antigen recognition and effector functions Figure 1 | Effects of IgG glycosylation on antigen recognition and effector functions. a | Schematic structures and individual components of the sugar moiety that can be attached to the IgG variable, or the Fc domain. Sugar residues are colour coded according to guidelines provided by the consortium for functional glycomics127. The sugar moiety is referred to either as IgG–G1F or IgG–G2F, depending on the presence of one, or two galactose residues. Sugar moieties without any terminal sialic acid (SA) and galactose (Gal) residues are referred to as IgG–G0F glycoforms. The fully processed sugar moiety contains terminal galactose and sialic acid residues on both arms. b | Sugar moieties attached to the IgG–Fc domain are rarely fully processed and can differ in composition within different constant heavy 2 (CH2) domains of the same IgG molecule. Certain sugar moieties, such as fucose, galactose and sialic acid are able to influence IgG effector functions. Certain IgG molecules are glycosylated in the antibody variable (Fab) region, owing to the generation of glycosylation sites during somatic hypermutation. Fab glycosylation can have positive or negative implications for antigen binding and antibody half-life, and might also have immunomodulatory effects. CH, constant heavy; CL, constant light; GlcNAc, N‑acetylglucosamine; Man, mannose; VH, Variable heavy; VL, Variable light. Seeling, M. et al. (2017) Differential antibody glycosylation in autoimmunity: sweet biomarker or modulator of disease activity? Nat. Rev. Rheumatol. doi:10.1038/nrrheum.2017.146