Effect of the acid-labile subunit on the binding of insulin-like growth factor (IGF)-binding protein-3 to [125I]IGF-I

The Journal of Clinical Endocrinology and Metabolism
A BarrecaF Minuto

Abstract

In normal subjects, the major form of circulating insulin-like growth factor (IGF) is the GH-dependent 150K complex. This complex is formed by the IGF peptide, the acid-stable binding protein IG-FBP-3, and the acid-labile subunit (ALS), which, although not binding IGF, appears to be necessary to reconstitute the complex in its natural form. The ALS was purified in our laboratory from human serum by ammonium sulfate precipitation, ion exchange chromatography using DEAE-Sephadex A-50, Concanavalin-A-Sepharose-4B chromatography, and two sequential gel filtrations by fast performance liquid chromatography. As demonstrated by gel permeation chromatography on fast performance liquid chromatography, incubation for 2 h at 20 C of this preparation with [125I]IGF-I and recombinant IGFBP-3 (rIGFBP-3) allows the reconstitution of a complex of about 150 kilodaltons. In these experimental conditions, the ALS is not only able to increase the mol wt of the complex, but also to greatly increase the amount of IGF-I bound; in the absence of ALS, radioactivity in the mol wt volume of the complexed forms was lower than that in the mol wt volume of the free form (percentage of total [125I]IGF-I: rIGFBP-3 alone, 15% and 44%; in the presence of ALS, 4...Continue Reading

Citations

May 10, 2006·Journal of Endocrinological Investigation·A BarrecaR Lorini
Nov 11, 2008·Journal of Endocrinological Investigation·A GiustinaUNKNOWN European Neuroendocrine Association
Sep 29, 2009·Journal of Veterinary Internal Medicine·R FinotelloF Minuto
Jan 1, 1995·Progress in Growth Factor Research·R C Baxter, S M Firth

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