Conformational change in an anti-integrin antibody: structure of OPG2 Fab bound to a beta 3 peptide

Biochem Biophys Res Commun. 1998 Oct 9;251(1):61-6. doi: 10.1006/bbrc.1998.9380.


Antibodies are important tools to explore receptor-ligand interactions. The anti-integrin antibody OPG2 binds in an RGD-related manner to the alphaIIb beta3 integrin as a molecular mimic of fibrinogen. The Fab fragment from OPG2 was cocrystallized with a peptide from the beta3 subunit of the integrin representing a site that binds RGD. The crystal structure of the complex was determined at 2.2-A resolution and compared with the unbound Fab. On binding the integrin peptide there were conformational changes in CDR3 of the heavy chain. Also, a significant shift across the intermolecular interface between the CH1-CL domains was observed so that the angle of rotation relating the two domains was reduced by 15 degrees. This unusual conformational adjustment represents the first example of ligand-induced conformational changes in the carboxyl domains of a Fab fragment.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Antigen-Antibody Complex / chemistry
  • Antigen-Antibody Complex / metabolism
  • Binding Sites, Antibody*
  • Crystallization
  • Immunoglobulin Fab Fragments / chemistry*
  • Immunoglobulin Fab Fragments / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Oligopeptides / metabolism*
  • Platelet Glycoprotein GPIIb-IIIa Complex / chemistry
  • Platelet Glycoprotein GPIIb-IIIa Complex / immunology*
  • Platelet Glycoprotein GPIIb-IIIa Complex / metabolism
  • Protein Conformation*
  • Solutions


  • Antigen-Antibody Complex
  • Immunoglobulin Fab Fragments
  • Oligopeptides
  • Platelet Glycoprotein GPIIb-IIIa Complex
  • Solutions
  • arginyl-glycyl-aspartic acid