Recombinant Human LR3 IGF-I/IGF-1

Insulin-like Growth Factor I (IGF-I), also known as Somatomedin C, is the dominant effector of Growth Hormone (GH) and is structurally homologous to Proinsulin. Human IGF-I is synthesized as two precursor isoforms with N- and alternative C-terminal propeptides ^[1]. These isoforms are differentially expressed by various tissues ^[1]. The 7.6 kDa mature IGF-I is identical between isoforms and is generated by proteolytic removal of the N- and C-terminal regions. Mature human IGF-I shares 94% and 96% amino acid (aa) sequence identity with the mouse and rat orthologs, respectively ^[2]. GH stimulates the production of IGF-I in most tissues ^[3]. Hepatocytes produce circulating IGF-I, while local IGF-I is produced by many other tissues in which it has paracrine effects ^[1]. IGF-I induces the proliferation, migration, and differentiation of a wide variety of cell types during development and postnatally ^{[4, 5]}. IGF-I regulates glucose, fatty acid, and protein metabolism, steroid hormone activity, and cartilage and bone metabolism ^[6-11]. It plays an important role in muscle regeneration and tumor progression ^{[1, 12, 13]}. IGF-I binds IGF-I R, IGF-II R, and the Insulin Receptor, although its effects are mediated primarily by IGF-I R ^[14]. IGF-I also binds with strong affinity to IGF binding proteins (IGFBPs), which regulate the availability and biological activities of IGF-I ^{[15, 16]}. Long R3 IGF-I (LR3 IGF-I) is a 9.2 kDa synthetic analog of IGF-I that is generated by modifying the aa sequence for mature human IGF-I. These modifications include the substitution of an Arg for Glu at position 3 of the mature IGF-1 sequence and the addition of a thirteen aa N-terminal extension, which is derived from methionyl porcine Growth Hormone ^[17].

Reference

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