Comparison of residues located at the interface of β3 and αIIb or β3 and αv that contribute to the stability of these complexes. The analysis was preformed using 1TXV PDB code for αIIbβ3 and 1JV2 for αvβ3. Only the β-propeller domain from the α subunits and the β-A domain from the β3 are displayed for clarity. αIIb, αv, and β3 are pink, cyan, and gray, respectively. In panels A and C, several residues located at the α-β interface are displayed as space-filled atoms, and in panel B, several residues are displayed in a balls-and-sticks representation and colored by atom type. Electrostatic connections are displayed as green lines. Amino acid abbreviations are shown in 1-letter codes. (A) Whereas residues Trp93, Met400-Pro401, and Lys369 located on αv form interactions with β3, their corresponding residues in αIIb are occupied by glycine residues (Gly92, Gly414, and Gly385, respectively) that lack similar contacts with β3. (B) The right panel displays a close view of the interface in the same orientation as presented in the left panel. The figure displays a network of electrostatic interactions connecting αv and β3. This network includes interactions between Lys119 (αv) and Asp179 (β3), and among Glu121, Glu123, and Asp148 in αv and Arg216 in β3. In contrast, the corresponding region at the αIIbβ3 interface exhibits a network of polar interactions that is mostly intrinsic to αIIb; Arg165 interacts with Glu123, Asp163, and Tyr166, all in αIIb. Only one intersubunit electrostatic interaction is conserved in αIIbβ3, that is, Glu123 (αIIb) and Arg216 (β3). (C) A salt bridge between αv-Arg245 and β3-Asp259. This electrostatic interaction is absent in the αIIbβ3 complex because the corresponding position in αIIb is occupied by the uncharged residue Thr259.