FVIIIa-interactive regions in FIXa. Structural model of FIXa³⁴ in which the putative regions interact with the FVIIIa A2 domain (dark blue), A3 domain (pale cyan), C1 domain (cyan), or C2 domain (light blue) are indicated. FIXa is shown in 2 orientations rotated 180° along the y-axis, and the individual FIXa domains are denoted. A detailed overview of the FIXa and FVIIIa regions is provided in Table 2. The figure was created with VMD 1.9.3. and BioRender.com.