IGF-1 LR3 (1mg)

Long R3 Insulin-like Growth Factor-1 (IGF-1 LR3) is a synthetic 83-amino acid recombinant analog of human IGF-1, engineered in the early 1990s by scientists at GroPep Limited (Adelaide, Australia) through collaborations with CSIRO and the University of Adelaide. IGF-1 LR3 incorporates two critical modifications: (1) a glutamic acid to arginine substitution at position 3 ("R3"), and (2) a 13-amino acid N-terminal extension (MFPAMPLSSLFVN). These modifications confer markedly reduced affinity for the six high-affinity IGF-binding proteins (IGFBPs), approximately three-fold greater potency at the IGF-1 receptor (IGF-1R), and a significantly extended half-life of approximately 20-30 hours compared to the approximately 12-15 hours of serum-bound native IGF-1.

Originally developed as a cell culture supplement to replace insulin at dramatically lower concentrations, IGF-1 LR3 has become a standard reagent in mammalian serum-free culture systems. Its reduced IGFBP binding makes it a uniquely valuable pharmacological tool for studying IGF-1R-mediated signaling without the confounding effects of IGFBP sequestration. IGF-1 LR3 has never been approved for human therapeutic use and is classified under section S2 of the World Anti-Doping Agency (WADA) Prohibited List.