Regulation and Actions of Insulin-Like Growth Factor Binding Protein-3
Binding proteins for the insulin-like growth factors (IGFs), first described 15 years ago, are now recognized as playing important roles as carriers of IGFs in the circulation, and modulators of IGF actions on target cells 1. Three distinct structural classes of IGF binding protein (IGFBP) have been identified on the basis of cDNA cloning 2–6, and at least two other structurally distinct proteins appear to exist 7–9. The predominant circulating IGFBP is an acid-stable glycoprotein with the systematic name IGFBP-3 . This paper will discuss recent studies, mainly from the authors’ laboratory, which relate to the dual roles of IGFBP-3, as part of the growth hormone (GH) dependent, high molecular weight ternary IGF complex in serum, and as local cell regulators of mitogenic actions of the IGFs.
KeywordsTernary Complex Follicular Fluid High Molecular Weight Form Ternary Complex Formation Bovine Fibroblast
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