A RAPID, NONRADIOACTIVE METHOD FOR THE DETECTION OF INSULIN-LIKE GROWTH-FACTOR BINDING-PROTEINS BY WESTERN LIGAND BLOTTING

Insulin-like growth factor binding proteins (IGFBPs) are produced by m any cell types and are present in a wide variety of biological fluids. Detection of IGFBPs in complex fluids is commonly performed by Wester n ligand blotting using I-125-IGF-I and/or I-125-IGF-II as the labelin g ligand. This method is extremely useful in detecting IGFBPs; however , it requires the use of radioactive materials and usually takes sever al days to weeks to complete. Herein, we report on a modification of t his method using biotinylated IGFs to detect both purified recombinant IGFBPs, as well as IGFBPs in fibroblast conditioned medium. This alte rnative method has proved sensitive, time- and cost-efficient, and it is environmentally safe.