IGF-1LR3

IGF-1 LR3 (Insulin-like Growth Factor 1 Long Arg3) is a synthetic analog of human IGF-1 with two key modifications: substitution of arginine for glutamic acid at position 3 (reducing affinity for IGF-binding proteins) and addition of a 13-amino acid N-terminal extension sequence. These modifications dramatically reduce binding to the six IGF-binding proteins (IGFBPs) that normally sequester IGF-1 in circulation, resulting in markedly increased bioavailability and an extended half-life of approximately 20–30 hours compared to native IGF-1's 12–15 minutes. Research using IGF-1 LR3 has extensively characterized the downstream effects of sustained, unattenuated IGF-1 receptor activation — effects difficult to study with endogenous IGF-1 due to rapid IGFBP sequestration. Scientific investigations have documented its effects on skeletal muscle satellite cell activation and hypertrophy, adipose tissue lipolysis, glucose metabolism via PI3K/Akt/mTOR signaling, and neuronal survival. IGF-1 LR3 is widely used in cell culture research as a potent mitogen and survival factor, and in animal models to study GH/IGF-1 axis effects independently of GH.