Recognition of insulin-like growth factor (IGF) serum binding proteins by an antibody raised against a specific IGF-inhibitor.
Evidence suggests that a specific inhibitor of the insulin-like growth factors (IGF) which acts by binding to IGF may be structurally related to the native, MW 150K binding protein (BP) in serum. This has now been examined using a polyclonal antiserum (R8) raised against highly purified inhibitor. Western blotting analysis of inhibitor using R8 gave 4 immunoreactive (ir-) bands (MW 34.5K, 23K, 16K and 12K), the most intense being the MW 16K band, identical to the MW of the inhibitor. Ligand blotting using 125I-IGF-I indicated specific IGF-binding activity at MW 29K, 26.5K, 16K and 12K, indicating that at least 2 of the ir-bands (16K and 12K) were IGF-BPs. Western blotting of a salt-precipitated fraction of serum gave 8 ir-bands of which 3 (MW 42K, 38K and 34K) were identical with BP bands detected previously by Hossenlopp et al (Anal. Biochem. (1986) 154, 138-143). These immunological crossreactivities indicate that the inhibitor is structurally related to the higher MW IGF-BPs in serum.
Ooi
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Medical Research Centre, Prince Henry's Hospital, Melbourne, Australia.
Herington
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D000645:Ammonium Sulfate; D000918:Antibody Specificity; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood* / Q000276:immunology; D011232:Chemical Precipitation; D000939:Epitopes / Q000276:immunology; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D018969:Insulin-Like Growth Factor Binding Proteins; D007457:Iodine Radioisotopes; D008970:Molecular Weight; D013002:Somatomedins / Q000037:antagonists & inhibitors*
D002352:Carrier Proteins; D000939:Epitopes; D007106:Immune Sera; D018969:Insulin-Like Growth Factor Binding Proteins; D007457:Iodine Radioisotopes; D013002:Somatomedins; D000645:Ammonium Sulfate