Engineering the C-region of human insulin-like growth factor-1: implications for receptor binding

Raj Gill*, Brenda Wallach, Chandra Verma, Birgitte Ursø, Elke De Wolf, Joachim Grötzinger, Judith Murray-Rust, Jim Pitts, Axel Wollmer, Pierre De Meyts, Steve Wood

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Recombinant wild-type human IGF-1 and a C-region mutant in which residues 28-37 have been replaced by a 4-glycine bridge (4-Gly IGF-1) were secreted and purified from yeast. An IGF-1 analogue in which residues 29-41 of the C-region have been deleted (mini IGF-1) was created by site-directed mutagenesis and also expressed. All three proteins adopted the insulin-fold as determined by circular dichroism. The significantly raised expression levels of mini IGF-1 allowed the recording of two-dimensional NMR spectra. The affinity of 4-Gly IGF-1 for the IGF-1 receptor was approximately 100-fold lower than that of wild-type IGF-1 and the affinity for the insulin receptor was approximately 10-fold lower. Mini IGF-1 showed no affinity for either receptor. Not only does the C-region of IGF-1 contribute directly to the free energy of binding to the IGF-1 receptor, but also the absence of flexibility in this region eliminates binding altogether. As postulated for the binding of insulin to its own receptor, it is proposed that binding of IGF-1 to the IGF-1 receptor also involves a conformational change in which the C-terminal B-region residues detach from the body of the molecule to expose the underlying A-region residues.

Original languageEnglish
Pages (from-to)1011-9
Number of pages9
JournalProtein Engineering
Issue number11
Publication statusPublished - 1 Nov 1996


  • Amino Acid Sequence
  • Animals
  • Chromatography, High Pressure Liquid
  • Circular Dichroism
  • Cloning, Molecular
  • Computer Simulation
  • Humans
  • Insulin-Like Growth Factor I/chemistry
  • Male
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Fragments/chemistry
  • Protein Binding
  • Protein Engineering/methods
  • Protein Folding
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, IGF Type 1/metabolism
  • Recombinant Proteins/chemistry
  • Saccharomyces cerevisiae/genetics


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