IGF-1 LR3

IGF-1 LR3 (Long R3 IGF-1)

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a synthetic recombinant analogue of human IGF-1 incorporating two structural modifications: an N-terminal methionine extension (the “Long” designation) and a glutamic acid-to-arginine substitution at position 3 (the “R3” designation). These modifications were designed to dramatically reduce binding affinity for IGF-binding proteins (IGFBPs) while maintaining full potency at the IGF-1 receptor (IGF-1R). IGF-1 LR3 has approximately 2–3 times the potency of native IGF-1 at IGF-1R and a significantly extended half-life in biological systems due to its reduced IGFBP sequestration, making it one of the most widely used research tools for studying IGF-1R-mediated anabolic and proliferative signalling.

Mechanism of Action

IGF-1 LR3 acts as a potent full agonist of the IGF-1 receptor (IGF-1R), a heterotetrameric receptor tyrosine kinase. Ligand binding induces receptor autophosphorylation and activation of the insulin receptor substrate (IRS) proteins, initiating downstream signalling through the PI3K/Akt/mTOR pathway (mediating protein synthesis, glucose uptake, and anti-apoptotic effects) and the Ras/MAPK/ERK pathway (mediating cell proliferation and differentiation). The Arg3 substitution reduces affinity for IGFBP-1, -2, -3, -4, -5, and -6 by approximately 1000-fold compared to native IGF-1, while the N-terminal extension further reduces IGFBP-3 binding. This results in a molecule that is predominantly in the free, bioactive form in biological systems, providing sustained IGF-1R activation that is not attenuated by endogenous IGFBP sequestration.

Research Applications

• IGF-1R pharmacology, receptor tyrosine kinase signalling, and IRS pathway studies
• PI3K/Akt/mTOR and MAPK/ERK anabolic signalling research
• IGFBP-independent IGF-1 signalling and extended half-life investigation
• Muscle hypertrophy, satellite cell biology, and skeletal muscle anabolism research
• Cell proliferation, differentiation, and anti-apoptotic signalling preclinical models

Specifications

• Molecular Formula: C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉
• Molecular Weight: 9117.5 g/mol
• CAS Number: 946870-92-4
• Purity: ≥98%
• Form: Lyophilised powder
• Storage: -20°C
• Shelf Life: 24 months

This product is intended for legitimate laboratory and analytical research use only. Not for diagnostic, therapeutic, or consumer use.