Fig. 6: Proposed binding mechanism for albicin with C3bBb in the fluid phase.
From: Mechanism of complement inhibition by a mosquito protein revealed through cryo-EM
On the left albicin is shown binding with C3bBb. The complex then dimerizes by addition of a second C3bBb complex giving the C3bBb-albicin structure shown in Figs. 4 and 5. FBb then dissociates from the complex producing complex with a single FBb molecule bound as represented by classes 1 and 2 from 3D classification. Dissociation of the second FBb molecule then produces the C3b-albicin dimeric structure shown in Figs. 2 and 3. Weakly bound albicin then dissociates leading to dissociation of the dimeric C3b structure as indicated in the size exclusion chromatography experiment after 14 h incubation shown in Fig. 1a.
