Quick Facts
Overview
IGF-1 LR3 (Long R3 Insulin-Like Growth Factor-1) is a modified analog of human IGF-1, an 83-amino acid protein that is a key mediator of growth hormone's anabolic effects. The LR3 modification involves two changes: substitution of arginine for glutamic acid at position 3 (R3) and addition of a 13-amino acid extension at the N-terminus (Long). These modifications dramatically reduce binding to IGF-binding proteins (IGFBPs), which normally sequester and inactivate circulating IGF-1. The result is a form of IGF-1 with approximately 3-fold greater potency than native IGF-1 and a significantly extended biological half-life. IGF-1 LR3 was originally developed as a research tool for studying IGF-1 receptor signaling in cell culture, where IGFBP interference complicated experimental results. It has since become widely used in preclinical research across muscle biology, metabolism, and cell proliferation studies.
Mechanism of Action
IGF-1 LR3 binds to and activates the IGF-1 receptor (IGF-1R) with similar affinity to native IGF-1, triggering autophosphorylation of the receptor's tyrosine kinase domain. This activates two major downstream signaling cascades: the PI3K/Akt/mTOR pathway (promoting protein synthesis, cell survival, and glucose uptake) and the Ras/MAPK/ERK pathway (promoting cell proliferation and differentiation). The key advantage of the LR3 modification is that reduced IGFBP binding means a much higher fraction of the administered peptide reaches target tissues in its active, unbound form. In cell culture, IGF-1 LR3 is approximately 2-3x more potent than native IGF-1 for stimulating cell proliferation and protein synthesis.
Research Applications
Muscle biology and hypertrophy research, cell proliferation studies, IGF-1 receptor signaling, body composition research, recovery and tissue repair models, metabolic research, in vitro cell culture supplement
Research Protocols
Protocol Reference
Safety Profile and Considerations
Potent growth factor - requires careful dosing in research applications. Hypoglycemia is a risk due to insulin-like effects on glucose uptake. Potential for promoting proliferation of existing abnormal cells (theoretical oncological concern). Not FDA approved. Most safety data derives from in vitro and animal research. Significantly more potent than native IGF-1 due to reduced IGFBP sequestration. For research use only.
Storage and Stability
Lyophilized: -20C. Reconstituted: 2-8C, use within 30 days. Very sensitive to degradation. See our storage and handling guide for comprehensive best practices.
Published Research
Search for additional IGF-1 LR3 research on PubMed.
Where to Source IGF-1 LR3
Peptide purity is critical for research accuracy. We evaluate suppliers against our 100-point methodology.
IGF-1 LR3 from Elara Research Peptides
Elara Research Peptides carries IGF-1 LR3 with batch-specific Certificates of Analysis from independent third-party laboratories. Every product verified at 99%+ purity via HPLC and mass spectrometry.
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