Human LR³ insulin-like Growth Factor-I (LR³IGF-I) is an 83 amino acid analogue of IGF-I comprising the complete human IGF-I sequence with the substitution of an Arginine for the Glutamine at position 3, plus a 13 amino acid extension peptide at the N-terminus.

Human LR³IGF-I is more potent than IGF-I in vitro and in vivo. This increased potency is due to reduced binding of LR³IGF-I to most of the IGF binding proteins which modify the biological actions of IGF-I. Human LR³IGF-I binds to the type 1 IGF receptor with similar affinity to wild type IGF-I.

LR³IGF-I was developed by GroPep specifically for supplementation of mammalian cell culture to support the survival and proliferation of cells. It is engineered to have a higher biological potency than native IGF-I or IGF-II and has several advantages over recombinant insulin. Supplementation of cell cultures with LR³IGF-I at a much lower concentration results in equivalent or better productivity than supplementation with standard concentrations of insulin. LR³IGF-I is better able to stimulate the type I IGF receptor and thus induce a higher level of activation of intracellular signalling molecules which are responsible for promoting cell survival by inhibition of apoptosis.

Receptor grade LR³IGF-I is a high quality research reagent for use in studies on cell growth, IGF receptors and IGF binding proteins.