Figure 3
From: Structural insights into the bi-specific cross-over dual variable antibody architecture by cryo-EM
Flexibility analyses of Fab and Fc domains of CODVIg. (a) and (b), The two components resulting from the 3D variability analysis (3DVA) of the TC map indicating the high flexibility present in IL4-binding and constant domains. Clockwise rotation for anti-IL4 Fv2 is observed in the variability component 1 whereas, as shown in (b), variability component 2 exhibits a counter-clockwise movement of the anti-IL4 Fv2. The first frame of the 3DVA volume series is in blue, while the last frame is in orange. These results are also shown as a “supplementary video". (c) Slices along planes of the three orthogonal axes are shown for the variability component 2 shown in b, with blue and red colors represent density to be added and subtracted from the mean density indicating the movement in either direction along the axes. (d) Superposition of the crystal structures of apo-CODVFab, CODVFab:IL4 and the cryo-EM structure of TC (this work) showing the movement of the constant domain in the antigen bound structures away from the antigen sites. This antigen induced conformational change is proposed to be transferred to the Fc region via the Fab-Fc hinge inducing additional flexibility to Fc. (e) Different classes from the 3D classification of CODV:IL4 indicating different structural dispositions of Fc relative to the Fabs.
