The stucture of FIX is based on that of Wang et al.⁶  The ribbon structure of the heavy chain of activated FIX appears in black and part of the light chain in pink. The amino acids of the catalytic triad (His221, Asp269, and Ser365) are identified in reds and pinks. The amino acids of normal FIX that were mutated to generate FIX-ITV are identified in blues and purples, with the amino acids present in FIX-ITV shown in parenthesis. PDB code is 3LC3. Jay W. Ponder assisted in preparing the figure.