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Expression and purification of biologically active IGF-binding proteins using the LCR/Mel expression system
Wendy Bagnall1, Paul M Sharpe, Peter Newham
1Respiratory and Inflammation Research Department, AstraZeneca Pharmaceuticals, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK.
Protein Expression and Purification
|January 3, 2003
Summary
This study demonstrates that the LCR/Mel expression system effectively produces biologically active insulin-like growth factor-binding proteins (IGFBPs), specifically IGFBP-3 and IGFBP-4, with binding properties comparable to native forms.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- Insulin-like growth factors I and II (IGF-I, IGF-II) are regulated by IGF-binding proteins (IGFBPs).
- Six IGFBP family members exist, each with unique structures and functions.
- Understanding IGFBP binding properties is crucial for studying IGF bioavailability and anabolic effects.
Purpose of the Study:
- To express recombinant IGFBP-3 and IGFBP-4 using the LCR/Mel expression system.
- To characterize the binding kinetics and biological activity of these recombinant IGFBPs.
- To compare the efficacy of the LCR/Mel system with other expression methods.
Main Methods:
- Recombinant IGFBP-3 and IGFBP-4 were expressed using the LCR/Mel system.
- Glycosylation patterns and molecular sizes of recombinant IGFBPs were analyzed.
- Binding kinetics were measured via solid-phase ligand-binding, in vitro solution-binding assays, and cellular proliferation assays.
- Recombinant IGFBPs were compared to those expressed in Escherichia coli.
Main Results:
- Recombinant IGFBP-3 exhibited native-like glycosylation; recombinant IGFBP-4 was non-glycosylated.
- Both recombinant IGFBP-3 and IGFBP-4 bound IGF-I and IGF-II with high affinity.
- IGF-II demonstrated higher affinity than IGF-I for both recombinant IGFBPs.
- Recombinant IGFBPs inhibited IGF-induced NIH3T3 cell proliferation.
- Mel cell-expressed IGFBPs showed equivalent binding kinetics to E. coli-expressed counterparts.
Conclusions:
- The LCR/Mel expression system is effective for producing biologically active IGFBPs.
- Recombinant IGFBP-3 and IGFBP-4 possess significant binding affinities for IGF-I and IGF-II.
- These findings support the LCR/Mel system as a viable method for IGFBP research and potential therapeutic development.