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A long-acting analog of insulin-like growth factor 1 with an arginine substitution at position 3 and a 13-amino acid N-terminal extension. Studies have investigated its enhanced anabolic activity and reduced IGF binding protein affinity.
IGF-1 LR3 (Long Arg3 IGF-1) is an 83-amino acid analog of human IGF-1 engineered with two key modifications: substitution of glutamic acid with arginine at position 3 (Arg3), and extension of the N-terminus by 13 amino acids. These changes dramatically reduce binding affinity for IGF binding proteins (IGFBPs 1-6), which normally sequester and inactivate circulating IGF-1. As a result, IGF-1 LR3 has a significantly longer half-life and greater bioavailability than native IGF-1. It activates the IGF-1 receptor (IGF-1R) to stimulate protein synthesis, glucose uptake, and cell proliferation through the PI3K/Akt and MAPK/ERK signaling pathways.
Francis GL, et al. Insulin-like growth factors 1 and 2 in bovine colostrum. Sequences and biological activities compared with those of a potent truncated form. Biochem J. 1988;251(1):95-103.
Key finding: Characterized the enhanced biological potency of IGF-1 analogs with reduced IGFBP binding, establishing the pharmacological rationale for the LR3 modification.
Tomas FM, et al. Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection. J Endocrinol. 1996;150(1):77-84.
Key finding: Demonstrated that IGF-1 LR3 maintained its superior potency over native IGF-1 in modulating nitrogen retention and anabolic signaling pathways when administered by injection in research models.
| Type | Peptide (IGF-1 analog, 83 amino acids) |
Research Use Only (RUO): This page summarizes published scientific research and is provided for educational and informational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendations. The compound described carries a Research Use Only designation and is intended for laboratory research use only. It is not intended for human or animal consumption, or for use in the diagnosis, treatment, cure, or prevention of any disease. Consult qualified professionals before making any health-related decisions.