Fig. 5.
CH2 domain AB loop movement in hexamer formation. Ile253 and Ser254 from the CH2 AB loop move to accommodate formation of the IgG hexamer. The arrow close to Ile253 indicates the direction of movement. The AB loop is shown for IgG1-Fc (white) (PDB accession number 3AVE; Matsumiya et al., 2011), glycosylated IgG4-Fc (green) (PDB accession number 4C54; Davies et al., 2014), chain B of the degly-Fc structure (pink) and intact IgG1 (blue) (PDB accession number 1HZH, Saphire et al., 2001). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)