Figure 2.

Mutations in amino acid residues in the Fc region to enhance FcRn affinity. Diagram of the Fc portion of human IgG1 (protein data bank (PDB) ID: 1DN2) was generated using RasMol (OpenRasMol).⁸⁰ FcRn binds at the CH2–CH3 hinge region of Fc at I253, H310, H430, and to a lesser extent H433 and Y436.¹²–¹⁴ Amino acid residues near the Fc hinge region mutated to increase binding to FcRn are grouped in colors according to the various combination listed in Table 1.