Figure 1

Binding of peptide ligands to the integrin surfaces. ( a ) Detail of the crystal structure of the extracellular region of αVβ3 integrin in complex with the cyclic pentapeptide Arg-Gly-Asp-D-Phe-N(Me)-Val [8]. The peptide (orange), sits across the interface between the αV (red) and β3 (green) integrin subunits, but only the three amino acids from the RGD triad make significant contact with the integrin surface. The Asp residue completes the coordination of one of the three Mn²⁺ ions (purple spheres) at the top of the β3 subunit. ( b ) Detail of the crystal structure of the extracellular region of αIIbβ3 integrin in complex with the cyclic peptide eptifibatide [12], showing very similar interactions. Hrg and Mpt indicate L-homoarginine and β-mercaptopropionic acid residues, respectively. Due to higher resolution, water molecules (cyan spheres) are seen in this structure to complete the coordination of the metal ions. Other colours as in panel a. Both figures have been prepared using SETOR [45].