Recombinant Human IGFBP3

IGFBPs are synthesized in the liver and are produced also by various tumor cell lines and cell types. IGFBPs are high affinity binding proteins for IGF. The major fraction of both types of IGF circulating in the blood are bound non- covalently to these carrier proteins. IGF binding proteins modulate IGF activities by increasing their plasma half lives and by inhibiting or promoting the interactions of IGF with receptors on certain target cells. In addition these binding proteins provide a reservoir for IGF in pericellular spaces. Some IGFBPs also have stimulating effects in vitro and some may inhibit the growth of cells. IGFBP1 is found predominantly in the placenta and the amniotic fluid. The predominant sites of IGFBP1 transcription in the human fetal kidney are those with most active differentiation. Elevated serum levels have been observed in patients with Laron-type dwarfism and Growth hormone deficiency. High serum levels of IGFBP1 are found in newborns and it has been suggested that this could be important in protecting them from hypoglycemia.