Crystal structure of the A domain from the alpha subunit of integrin CR3 (CD11b/CD18)

Cell. 1995 Feb 24;80(4):631-8. doi: 10.1016/0092-8674(95)90517-0.


We have determined the high resolution crystal structure of the A domain from the alpha chain of integrin CR3. The domain adopts a classic alpha/beta "Rossmann" fold and contains an unusual Mg2+ coordination site at its surface. One of the coordinating ligands is the glutamate side chain from another A domain molecule. We suggest that this site represents a general metal ion-dependent adhesion site (MIDAS) for binding protein ligands. We further propose that the beta subunits of integrins contain a MIDAS motif within a modified A domain. Our crystal structure will allow reliable models to be built for other members of the A domain superfamily and should facilitate development of novel adhesion modulatory drugs.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Crystallography, X-Ray
  • Fibrinogen / metabolism
  • Integrins / chemistry*
  • Integrins / genetics
  • Intercellular Adhesion Molecule-1 / metabolism
  • Macrophage-1 Antigen / chemistry*
  • Macrophage-1 Antigen / genetics
  • Macrophage-1 Antigen / metabolism
  • Magnesium / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Fragments / chemistry*
  • Peptide Fragments / genetics
  • Protein Binding
  • Protein Conformation
  • Recombinant Fusion Proteins / chemistry
  • Structure-Activity Relationship


  • Integrins
  • Macrophage-1 Antigen
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • Intercellular Adhesion Molecule-1
  • Fibrinogen
  • Magnesium