Fig. 1. Crystal structures of the Fc region of IgG1 with Trp residues shown in red. Each chain is shown in green and light green colors. Recognition residues of the three proteins are shown in different colors: magenta (FcγRIIIa, CD16a), cyan (C1q), blue (overlapped residues of FcγRIIIa and C1q), and orange (FcRn). PDB ID: 1E4K.
