Role of growth-hormone and insulin-like growth-factor-binding proteins.
Some peptide hormones are associated with specific, high-affinity plasma proteins. The major binding protein (BP) for growth hormone (GH) in humans is a circulating fragment of the GH membrane receptor, consisting of the hydrophilic, extracellular portion of that transmembrane glycoprotein. The circulating levels of GH-BP mirror the levels of GH receptors. There are 4 well-characterized insulin-like growth factor (IGF)-BPs. One IGF-binding component in plasma is a fragment of the extracellular portion of the IGF-II/mannose-6-phosphate receptor, analogous to the GH-BP. The 3 other cloned IGF-BPs form a homologous family of proteins with differences in structure, glycosylation and hormonal control that suggest differences in function. The GH- and IGF-BPs play a major role in the metabolism and biological action of these peptide hormones.
Department of Pediatrics, Stanford University Medical Center, Calif.
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Hintz
D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D011986:Receptors, Somatotropin / Q000378:metabolism; D013002:Somatomedins / Q000378:metabolism
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D011986:Receptors, Somatotropin; D013002:Somatomedins; D013006:Growth Hormone; C051815:somatotropin-binding protein