Fig. 5.

Comparison between crystal structures and EM class averages of C3b. (A) Cross-correlation of a group I class average of C3b (image 1) with projections from C3b crystal structures from Janssen et al. (29) (image 2; PDB entry 2I07), Wiesmann et al. (28) (image 3; PDB entry 2ICF, the C3b moiety only), and Ajees et al. (27) (image 4; PDB entry 2HR0), and from the rigid body model described in Fig. 3 (image 5) was as described in the legend of Fig. 3. (B) Representative group II (image 1) and III (image 2) class averages of C3b from Fig. 2C. (C and D) Two crystal structures and two EM-based rigid body models of C3b from Fig. 3 F and G superimposed by using the C3c-moiety (shown in gray for all four). The CUB domain and TED are green (group I model), cyan (group II model), magenta [structure by Janssen et al. (29)], and gold (structure by Ajees et al.). (C) View in group I orientation of A. (D) Stereoview in group II orientation of image 1 of B.