Insulin-like growth factor binding proteins-3 and -5 form sodium dodecyl sulfate-stable multimers

Biochem Biophys Res Commun. 1997 Nov 26;240(3):707-14. doi: 10.1006/bbrc.1997.7726.

Abstract

Insulin-like growth factor binding proteins (IGFBPs) are important modulators of IGF actions. IGFBP-3 and IGFBP-5 can bind to the extracellular matrix of a number of cell types. We now describe a new posttranslational structural modification of IGFBP-3 and IGFBP-5, which could play a role in determining their localization. We incubated radioiodinated forms of all six IGFBPs in the presence of a redox buffer consisting of 10 mM reduced glutathione and 0.2 mM oxidized glutathione. Under these conditions IGFBP-3 and IGFBP-5, but not the other IGFBPs, formed high molecular weight disulfide-linked multimers. Heparin and a peptide encompassing the high-affinity heparin-binding site in the C-terminal portion of IGFBP-3 were capable of blocking the multimerization of IGFBP-3. IGFBP-3, but not IGFBP-1, was shown to be able to self-associate non-covalently, which could be a requisite first step in the formation of covalent multimers. The self-association of IGFBP-3 required the high-affinity heparin-binding site in the C-terminal portion of the molecule.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Chromatography, Gel
  • Electrophoresis, Polyacrylamide Gel
  • Glutathione / pharmacology
  • Glutathione Disulfide / pharmacology
  • Heparin / pharmacology
  • Humans
  • Insulin-Like Growth Factor Binding Protein 3 / chemistry*
  • Insulin-Like Growth Factor Binding Protein 3 / metabolism
  • Insulin-Like Growth Factor Binding Protein 5 / chemistry*
  • Insulin-Like Growth Factor Binding Protein 5 / metabolism
  • Insulin-Like Growth Factor I / metabolism
  • Iodine Radioisotopes / analysis
  • Iodine Radioisotopes / metabolism
  • Macromolecular Substances
  • Molecular Sequence Data
  • Molecular Weight
  • Oxidation-Reduction
  • Peptide Fragments / pharmacology
  • Protein Conformation*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sodium Dodecyl Sulfate / pharmacology*

Substances

  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor Binding Protein 5
  • Iodine Radioisotopes
  • Macromolecular Substances
  • Peptide Fragments
  • Recombinant Proteins
  • Sodium Dodecyl Sulfate
  • Insulin-Like Growth Factor I
  • Heparin
  • Glutathione
  • Glutathione Disulfide