Structure of complement fragment C3b–factor H and implications for host protection by complement regulators

Complement forms an ancient innate immune defense. Gros and colleagues provide new insight into the interactions between complement convertase C3b and its regulator factor H and with the staphylococcal inhibitor SCIN. Factor H (FH) is an abundant regulator of complement activation and protects host cells from self-attack by complement. Here we provide insight into the regulatory activity of FH by solving the crystal structure of the first four...