Structural characterization and comparison of RGD cell-adhesion recognition sites engineered into streptavidin

Acta Crystallogr D Biol Crystallogr. 2003 May;59(Pt 5):828-34. doi: 10.1107/s0907444903004153. Epub 2003 Apr 25.


The RGD (arginine-glycine-aspartic acid) sequence is found in several important extracellular matrix proteins and serves as an adhesion ligand for members of the integrin family of cell-surface receptors. This sequence and flanking residues from fibronectin or osteopontin have been engineered into an accessible surface loop of streptavidin to create two new streptavidin variants (FN-SA or OPN-SA, respectively) that bind cells through the alpha(v)beta(3) and/or alpha(5)beta(1) integrin receptors. Their crystal structures confirm the design and construction of the mutants and provide evidence about the conformational dynamics of the RGD loops. The loops in the isomorphous crystal structures are involved in crystal-packing interactions and this stabilizes their structures. Even so, the loop in OPN-SA is slightly disordered and two of the residues are not seen in difference electron-density maps. Comparison with other experimentally determined structures of RGD loops in cell-adhesion molecules shows that these loops occupy a large subset of conformational space. This is consistent with the view that RGD loops, at least those involved in cell adhesion, sample a number of structures dynamically, a few of which display high affinity for appropriate receptors.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Cell Adhesion
  • Cell Adhesion Molecules / chemistry
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism
  • Crystallography, X-Ray
  • Fibronectins / chemistry
  • Fibronectins / genetics
  • Fibronectins / metabolism
  • Hydrogen Bonding
  • Integrin alpha5beta1 / metabolism
  • Integrin alphaVbeta3 / metabolism
  • Models, Molecular
  • Oligopeptides / chemistry*
  • Oligopeptides / metabolism
  • Osteopontin
  • Protein Conformation
  • Protein Engineering
  • Sialoglycoproteins / chemistry
  • Sialoglycoproteins / genetics
  • Sialoglycoproteins / metabolism
  • Streptavidin / chemistry*
  • Streptavidin / genetics*
  • Streptavidin / metabolism


  • Cell Adhesion Molecules
  • Fibronectins
  • Integrin alpha5beta1
  • Integrin alphaVbeta3
  • Oligopeptides
  • Sialoglycoproteins
  • Osteopontin
  • arginyl-glycyl-aspartic acid
  • Streptavidin