Figure 2 Influence of fucosylation on IgG effector functions Figure 2 | Influence of fucosylation on IgG effector functions. a | Structure of the human low-affinity immunoglobulin‑γ Fc region receptor III‑A (FcγRIIIa, green) bound to the human IgG1 Fc domain (blue and red), with magnification of the interaction site of both sugar moieties of the FcγRIIIa (depicted as a yellow ball-and-stick model) and of one IgG Fc domain (blue ball-and-stick model). The fucose residue of the antibody sugar moiety (depicted in red) clashes with the sugar domain of FcγRIIIa, resulting in low-affinity binding. b | Activating (FcγRIa, IIa, IIc, IIIa) and inhibitory (FcγRIIb) FcγRs. These receptors mediate signalling through immunoreceptor-tyrosine-based activatory (ITAM) or inhibitory (ITIM) motifs. FcγRIIIb is linked via a glycerolphosphatidylinositol (GPI) anchor to the plasma membrane and does not connect with the activating FcRγ-chain. Green arrows indicate the increased selectivity of IgG glycosylation variants without fucose for FcγRIIIa (expressed on mast cells, basophils, eosinophils, dendritic cells, monocytes, macrophages, natural killer (NK) cells) and FcγRIIIb (expressed on neutrophils). Increased binding of IgGs to effector cells might result in an increase in magnitude of the depicted effector responses. ADCC, antibody-dependent cell-mediated cytotoxicity. Part a modified with permission from Nimmerjahn, F. & Ravetch, J. V. Fcgamma receptors as regulators of immune responses. Nat. Rev. Immunol. 8, 34–47 (2008). Part a modified with permission from Nimmerjahn, F. & Ravetch, J. V. Fcgamma receptors as regulators of immune responses. Nat. Rev. Immunol. 8, 34–47 (2008). 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