Fig. 4: Structural rearrangements between “open” and “closed” conformations.

a “Closed” (left panel) and “open” (right panel) conformations of the Nap complex. The “closed” conformation associated with the release state of the sialylated oligosaccharides cell receptors. The “open” conformation associates with the bound and ready-to-bind state. b Bottom view along the Nap twofold axis, depicting points of contact (black circles) between subunits and the mycoplasma cell outer membrane. These points also mark the start (the N-terminal ends) of the transmembrane helices. The N-terminal end positions are changing from a squared to rhomboid shape, when transitioning from the closed to the open conformation. c Changes to the relative positions of the C-terminal domains from P140 (upper panels) and P110 (lower panels).