Cryo-EM structure of the ET3i:NB33 complex. Cryo-EM map (A) and structure (B) of ET3i bound to NB33 Fab fragment. (dark blue, porcine A1 domain; slate, human A2 domain; cyan, porcine A3 domain; orange, human C1 domain; yellow, human C2 domain; dark purple, NB33 heavy chain; and light pink, NB33 light chain). (C-E) Intermolecular contacts between ET3i residues (C-D) R2090-F2093 and (E) I2158-R2159 (orange) and NB33 heavy (dark purple) and light (light pink) chains. The dashed lines represent noncovalent interactions ≤5 Å.