Mapping epitopes onto the trans TPO dimer.

(A) Epitopes and residues identified in various studies as constituting immunodominant regions IDR-A (blue) and IDR-B (pink); (B) Membrane-facing side of MPO-like domain; (C) Close-up shows that much of the two immunodominant regions are on the membrane-facing surface of the MPO-like domain, particularly IDR-B; (D) Lumen-facing side of TPO. Hemes are shown in orange.