Structure of the FXIIFnII domain gC1qR interface. (A) Diagram of the FXIIFnII-gC1qR complex colored as in Figure 1E. The gC1qR G1-loop, residues 196 to 204 (red), and pockets G1 and G2 are labeled interacting with FXII residues Arg36 and Arg65 (orange) shown as sticks. Electrostatic interactions are shown as purple dotted lines and the Zn²⁺ as a blue sphere. (B) Interactions of the gC1qR G1-loop with FXII are shown as 2 different views. (C) The gC1qR G2 pocket is shown (purple), and key interacting FXII residues and the gC1qR residue Trp233 are shown as sticks (wheat). (D) A charged surface representation of the gC1qR G1 and G2 pockets, with FXIIFnII in cyan as a cartoon diagram with key interacting side chains as sticks.