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. Author manuscript; available in PMC: 2012 Nov 28.
Published in final edited form as: Nat Rev Immunol. 2010 May;10(5):317–327. doi: 10.1038/nri2744

Figure 2. IgG structure and function.

Figure 2

IgG is composed of two heavy and light chains consisting of constant regions, which contribute to the Fc domain, and variable regions, which contribute to antigen specificity (panel A). Antigen coated with IgG can bind Fc receptors and initiate signalling through immunoreceptor tyrosine-based activation motifs (ITAMs) or immunoreceptor tyrosine-based inibitory motifs (ITIMs) (panel B). IgG can bind neonatal Fc receptors (FcRn) on endothelial cells to maintain serum IgG levels (panel C) or bind to tumour cells and recruit C1q to initiate the complement cascade, resulting in tumour cell lysis by the membrane attack complex (MAC) (panel D).