Insulin‐Like Growth Factors I and II: Some Biological Actions and Receptor Binding Characteristics of Two Purified Constituents of Nonsuppressible Insulin‐Like Activity of Human Serum

作者：Jürgen Zapf, Eugen J. Schoenle, Ernst Rudolf Froesch · 发表于：European Journal of Biochemistry · 年份：1978 · DOI：10.1111/j.1432-1033.1978.tb12377.x · 被引用次数：380 · 研究领域：Metabolism, Diabetes, and Cancer、Growth Hormone and Insulin-like Growth Factors、TGF-β signaling in diseases

The insulin‐like growth factors I and II, two purified constituents of nonsuppressible insulinlike activity opf human serum, have nbeen compared with regard to some bniological actions in vitro and some receptor‐binding characteristics. In the presence of an excess of insulin‐antibodies the insulin‐like growth factors I and II (a) stimulate the net gas exchange in rat adipose tissue (fat pad assay) to a similar extent; (b) enhance 3‐O‐methylglucose transport, glucose oxidation and lipogenesis from glucose in rat adipocytes, with slight but significant differences in potency; (c) inhibit lipolysis in adipose tissue from fastedrefed rats, again with slight potency differences. In adipose toissue and adipocytes the biological activity of insulin‐like growth factors I and II is between 1/35 and 1/125 of that of insulin on a molar basis. Insulin‐like growth factors I and II are equally potent mitogens (stimulation of DNA‐synthesis and cell multiplication in cultured chick embryo fibroblasts). Insulin‐like growth factors I and II stimulate 35SO42‐ incorporation into rat costal cartilage with minor differences in potency. In rat adipocytes, insulin‐like growth factors I and II compete with insulin for binding to thje insulin receptor. However, their potencies in ‘displacing’125I‐labeled insulin are between 75 (for factor II) and 290 times (for factor I) lower than that of insulin. In addition, the factors I and II bind to binding sites specific for the factors and for which insulin ...