What is IGF-1 LR3? A Researcher's Guide to the Long-Acting IGF-1 Analogue

IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3) is a synthetic analogue of human IGF-1, engineered for significantly extended half-life and enhanced potency compared to native IGF-1. It is one of the most widely used IGF-1 variants in research, valued for its ability to activate IGF-1 receptor signalling with reduced binding to IGF-binding proteins (IGFBPs), making it a cleaner tool for studying IGF-1 receptor-mediated pathways.

What is IGF-1 LR3?

IGF-1 LR3 is a 83-amino acid analogue of human IGF-1 with two key modifications: an N-terminal 13-amino acid extension and a glutamic acid substitution at position 3 (Arg→Glu). These modifications dramatically reduce binding affinity for IGF-binding proteins (IGFBPs), which normally sequester native IGF-1 in circulation and limit its bioavailability. The result is a compound with approximately 2–3x greater potency than native IGF-1 and a half-life of approximately 20–30 hours compared to native IGF-1’s 12–15 minutes.

Mechanism of Action

IGF-1 LR3 acts as a full agonist at the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase that activates downstream signalling pathways including:

  • PI3K/Akt pathway — promotes cell survival, protein synthesis, and glucose uptake
  • MAPK/ERK pathway — promotes cell proliferation and differentiation
  • mTOR activation — stimulates protein synthesis and inhibits autophagy

By reducing IGFBP binding, IGF-1 LR3 ensures a greater proportion of administered compound remains bioavailable to activate IGF-1R, making it more efficient for receptor-level research than native IGF-1.

Why IGF-1 LR3 is of Research Interest

IGF-1 LR3’s enhanced potency and extended half-life make it a preferred tool for IGF-1 axis research. Key areas of ongoing research include:

  • Muscle hypertrophy and protein synthesis models
  • Satellite cell activation and muscle regeneration
  • Bone growth and skeletal metabolism
  • Neuroprotection and neuronal survival research
  • Cancer biology (IGF-1R signalling in tumour models)
  • Metabolic disease and insulin resistance research
  • GH/IGF-1 axis comparative studies

IGF-1 LR3 vs. Native IGF-1

Key distinctions for research design:

  • Native IGF-1 — high IGFBP binding; short half-life (~15 min); lower effective bioavailability
  • IGF-1 LR3 — minimal IGFBP binding; extended half-life (~20–30 hrs); 2–3x greater potency at IGF-1R; preferred for in vivo and cell culture research

Sourcing IGF-1 LR3 for Research

Research-grade IGF-1 LR3 should be sourced from suppliers providing batch-specific Certificates of Analysis (CoA) confirming purity (>98%), identity, and potency. Lyophilised formats offer optimal stability for laboratory storage.

At Aura Peptides, our IGF-1 LR3 is supplied as a research-grade lyophilised peptide with full CoA documentation, available as single vials or in 10x bulk packs for high-volume research programmes.

For research purposes only. Not intended for human or veterinary use.

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