IGF-1 LR3 binds to the IGF-1 receptor (IGF-1R) on cell surfaces, activating the receptor tyrosine kinase domain and triggering two major downstream pathways: the PI3K/Akt/mTOR pathway (promoting protein synthesis and cell survival) and the Ras/MAPK pathway (promoting cell proliferation and differentiation). The LR3 modification reduces sequestration by IGFBPs, allowing sustained receptor activation and more potent biological effects compared to native IGF-1.
Research Use Only
IGF-1 LR3 — Long-Acting Insulin-Like Growth Factor
A modified form of insulin-like growth factor-1 with an extended half-life, studied for its potent effects on cell proliferation, tissue growth, and metabolic regulation.
Muscle GrowthGrowth HormoneTissue Repair
CAS 946870-92-4 • ~9,111 g/mol • Prepared for research use • Per research workflow
IGF-1 LR3 Structure
Reference identifiers are batch-specific for coded materials and are documented on the lot COA/SDS rather than inferred or estimated.
Mechanism of Action
IGF-1 LR3 Overview
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a recombinant analog of human IGF-1 with two key modifications: a glutamic acid to arginine substitution at position 3 and a 13-amino-acid N-terminal extension peptide. These modifications reduce binding to IGF-binding proteins (IGFBPs), resulting in a significantly longer half-life and greater bioavailability compared to native IGF-1. Native IGF-1 is a 70-amino-acid polypeptide produced primarily by the liver in response to growth hormone stimulation. It mediates many of the anabolic and growth-promoting effects of growth hormone, including stimulation of protein synthesis, cell proliferation, and inhibition of apoptosis. However, over 95% of circulating IGF-1 is bound to IGFBPs, limiting its bioactivity. The LR3 modification circumvents this limitation. By reducing IGFBP binding affinity by approximately 100-fold, IGF-1 LR3 maintains higher free concentrations in tissue, producing more potent activation of the IGF-1 receptor and downstream PI3K/Akt/mTOR signaling. This makes IGF-1 LR3 a valuable research tool for studying growth factor biology, muscle hypertrophy, and metabolic regulation. PharmaOrder supplies IGF-1 LR3 with COA available for research use.
Purity & Testing
IGF-1 LR3 is listed as 0.1mg lyophilized vial; 1mg lyophilized vial. Catalog identity: CAS 946870-92-4; molecular weight ~9,111 g/mol. The lot COA for IGF-1 LR3 is available in your account. Finnrick Analytical performs HPLC purity analysis and mass spectrometry identity confirmation on that lot.
- Catalog configurations: 0.1mg lyophilized vial, 1mg lyophilized vial
- CAS: 946870-92-4
- Molecular weight: ~9,111 g/mol
See the IGF-1 LR3 COA page.
Storage & Handling
Store the lyophilized powder at -20°C, protected from light; bring to room temperature before opening. For in-vitro preparation use an appropriate laboratory diluent.
Shipping
Ships worldwide from 6 distribution centers via USPS Ground Advantage
Available for direct research purchase
Research-use-only products are sold strictly for laboratory and research purposes. By purchasing, you acknowledge that these products are not intended for human or veterinary use, and you agree to PharmaOrder's RUO terms of service.
Published Research
Selected peer-reviewed studies referenced in this product overview.
Insulin-like growth factor-I (IGF-I) and its analogues: effects on muscle growth and repair
Goldspink G. — Journal of Endocrinology (2005)
Reviews IGF-1 and its long-acting analogs in muscle hypertrophy, satellite cell activation, and the PI3K/Akt/mTOR anabolic signaling cascade.
Long-R3-IGF-I is markedly more potent than IGF-I for stimulating muscle protein synthesis
Tomas FM, Knowles SE, Owens PC, et al. — American Journal of Physiology (1993)
Demonstrated that Long R3 IGF-1 is significantly more potent than native IGF-1 for stimulating muscle protein synthesis due to reduced IGFBP binding.
Insulin-like growth factor-I receptor signaling is required for exercise-induced cardiac hypertrophy
Kim J, Wende AR, Sena S, et al. — Molecular Endocrinology (2008)
Showed IGF-1 receptor activation through the PI3K/Akt pathway is essential for adaptive cardiac and skeletal muscle growth responses.
FAQ
What is IGF-1 LR3?
IGF-1 LR3 is a modified analog of human insulin-like growth factor-1. The LR3 modification (Arg3 substitution + 13-amino-acid extension) reduces binding to IGF-binding proteins, resulting in a longer half-life and greater potency than native IGF-1.
How does IGF-1 LR3 differ from native IGF-1?
Native IGF-1 is over 95% bound to IGFBPs in circulation, limiting its bioactivity. IGF-1 LR3 has approximately 100-fold lower affinity for IGFBPs, so more of the peptide remains free to activate IGF-1 receptors, producing stronger and more sustained growth signaling.
How should IGF-1 LR3 be stored?
Store the lyophilized powder at -20 degrees C, protected from light; bring to room temperature before opening. For in-vitro preparation use an appropriate laboratory diluent. Avoid repeated freeze-thaw cycles.
Editorial Review
Updated March 2026. Reviewed against product catalog, quality, and fulfillment standards. This page is educational and not instructions for human use. See our editorial standards and quality process.
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