Recombinant Human IGF-I (Animal-Free)

IGF-I (insulin-like growth factor 1), initially described in 1957, is a hormone that is important in childhood growth and also has anabolic effects in adults. It is a member of the IGF family that is comprised of three members: IGF-I, IGF-II, and insulin. IGF-I and IGF-II share approximately 50% similarity with insulin at the amino acid level. Human IGF-I is synthesized as a 191 amino acid prepro-IGF-I; pro-IGF-I is processed to the mature, active protein, and this procedure requires glucose regulating protein 94 (GRP94) that possesses chaperone activity towards IGF-I. Deletion of muscle GRP94 impairs muscle and body growth by inhibiting local production of IGF proteins. Seven IGF binding proteins have been described (IGFBP-1 to -7). IGFBPs extend the half life and regulate the availability of IGF-I and IGF-II. It has been described that IGFBP3 is the main circulating binding protein for IGFs; in serum, approximately 75% of circulating IGF-I and IGF-II bind to IGFBP3 and the co-carrier acid labile subunit (ALS). IGF-I binds to three receptors, and the binding to IGFIR promotes cell proliferation, survival, differentiation, and migration. IGF-I deficiency is associated to growth hormone insensitivity syndrome (GHIS) also called Laron syndrome, liver cirrhosis, age-related cardiovascular and neurological diseases, and intrauterine growth restriction.