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. 2023 Jul 13;14:4168. doi: 10.1038/s41467-023-39763-0

Fig. 4. Structure of full-length αIIbβ3 bound to the drug eptifibatide.

Fig. 4

Unsharpened cryo-EM map of full-length αIIbβ3 (αIIb in light blue and β3 in orange). The map at the overall resolution of 3.1 Å shows only a density for the integrin αIIb propeller, βA-, hybrid- and PSI domains of the headpiece, but densities are not visible for the thigh, leg, and TM domains, indicating that these domains display conformational variability. In a, the αIIb propeller is superposed onto that of the full-length inactive cryo-EM structure (gray) to show the large swingout of the hybrid domain of the eptifibatide-bound integrin. Eptifibatide is shown in green. The metal ions (spheres) at LIMBS (gray), MIDAS (cyan), and ADMIDAS (magenta) of the βA domain are shown. b Closeup view of the EM density for bound eptifibatide and the surrounding 6 Å density zone in a different viewing angle from that in a. Eptifibatide’s homoarginine (HRG) makes a salt bridge (red dotted line) with the propeller’s D224, and its Asp (D) monodentately coordinates (red dotted line) the Mg2+ ion (cyan sphere) at MIDAS. The eptifibatide structure fits that reported in the crystal structure of the eptifibatide/αIIbβ3 headpiece complex (2VDN.pdb), except that the tryptophan (W) side chain was moved to better fit into the observed EM density. The ADMIDAS Ca2+ ion is shown (magenta sphere). c Closeup of residues 419–422 of the propeller domain showing the fit into the EM density.