Comparison of the anchor region (blue) preceding the C345c domain in the SCIN‐stabilized C3bBbPc complex (left) and in native C3 (right, RCSB entry 2A73) (Janssen
et al,
2005). The α‐helical conformation is found only in C3 and in C3b bound to FH or MCP. The β‐hairpin is present in all other known structures of C3b and C3c.