The inclusion of the type III repeat ED-B in the fibronectin molecule generates conformational modifications that unmask a cryptic sequence

J Biol Chem. 1992 Dec 5;267(34):24689-92.

Abstract

We have previously reported an anti-fibronectin monoclonal antibody (mAb) (BC-1) which reacts with an ED-B-containing beta-galactosidase-fibronectin fusion protein but not with an identical beta-galactosidase-fibronectin fusion protein in which the ED-B sequence is omitted. In further experiments aimed at localizing more precisely the epitope recognized by this mAb, we demonstrate that 1) the mAb BC-1 is indeed specific for ED-B-containing fibronectin (FN) molecules even though the epitope recognized by this mAb is localized on the type III homology repeat 7 (the one which precedes the ED-B sequence) and 2) in fibronectin molecules lacking the ED-B sequence, this epitope is masked. We further demonstrate that, to mask the epitope recognized by the mAb BC-1, the presence of at least half of the FN type III homology repeat 9 is necessary. We also report the production of the mAb IST-6 which recognizes only FN molecules in which the ED-B sequence is lacking. These data clearly demonstrate that the presence of the ED-B sequence within FN molecules generates conformational modification in the central part of the molecules that unmasks previously cryptic sequences and masks others.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibodies, Monoclonal*
  • Cell Line
  • Cell Line, Transformed
  • Cloning, Molecular
  • Epitopes / analysis
  • Escherichia coli / genetics
  • Fibronectins / chemistry*
  • Fibronectins / genetics*
  • Fibronectins / immunology
  • Humans
  • Immunoenzyme Techniques
  • Macromolecular Substances
  • Protein Conformation*
  • Radioimmunoassay
  • Recombinant Fusion Proteins / immunology
  • Repetitive Sequences, Nucleic Acid*
  • Sequence Homology, Amino Acid
  • beta-Galactosidase / genetics
  • beta-Galactosidase / immunology

Substances

  • Antibodies, Monoclonal
  • Epitopes
  • Fibronectins
  • Macromolecular Substances
  • Recombinant Fusion Proteins
  • beta-Galactosidase