Conformational transition model of αIIbβ3 by the separation of TM domains. (A) To facilitate comparison, simplified figures demonstrating the path of linearly linked extracellular domains in αIIb (blue) and β3 (red) in the crystal structure and in the EM map from this study are displayed as the solid lines (legs) and the closed circles (head domains). Yellow arrows indicate the ligand-binding site. (B) Proposed model of conformational αIIbβ3 transition during inside-out signaling.