Test #140152The insulin-like growth factor (IGF) system plays a critical role in the growth and differentiation of normal and malignant cells. The components of the IGF system include growth hormone (GH), IGF-I and II, type I and II receptors, IGF binding proteins and proteases. IGF binding proteins were first identified for their high affinity interactions with IGF-I and IGF-II.2IGFBP-3 is the most abundant IGFBP species in circulation and binds 75% to 90% of circulating IGF-I in a ternary complex consisting of IGFBP-3, IGF-I and acid-labile subunit (ALS). IGFBP-3 modulates the activity of IGF-1 and to increase their half lives. It has been postulated that IGFBP-3 is regulated by GH and originates in the liver as low levels were observed in patients with impaired hepatic function.3IGFBP-3 has historically been used in the investigation of growth hormone deficiency, acromegaly, hypopituitarism and to monitor recombinant GH therapy.4,5 IGFBP-3 is known to modulate the actions of IGFs in circulation as and at the IGF-1 receptor.3 IGFBP-3 has also been shown to exhibit distinct biological effects independent of the IGF/IGF-1 receptor axis.6,7 Recent studies have impaired interaction of IGFBP-3 with a variety of proteins or signaling cascades critical to cell cycle control and apoptosis; however, the actual mechanism of IGFBP-3 action is unclear.6
Baxter RC, Martin JL. Radioimmunoassay of growth hormone-dependent insulin-like growth factor binding protein in human plasma.
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