Hormones
IGF-1 LR3
IGF-1 LR3, written in full as Long [Arg3]-IGF-I, is a lab-made version of human insulin-like growth factor 1. Two changes set it apart from the natural protein: an arginine sits where glutamate normally would at the third position, and a short extra stretch of amino acids is attached at the N-terminal end. The 1992 paper that introduced it framed it as a tool for probing how IGF-I behaves.
- Container
- Glass vial, crimp seal, flip-top cap
- Storage
- -20 °C, desiccated
- Paperwork
- Lot certificate (HPLC + mass spec) shown before you pay
Lot certificates
You’ll see American Peptides on the lab’s copy. They’re our supplier.
- 1 mg, lot IGF1-0803: 99.55% purity (RP-HPLC), 1.12 mg measured, identity confirmed by mass spec. Issued 2026-08-28 by Bioviridian Inc.. Verify certificate COA7588
Our vials are filled from lots made by our supplier, American Peptides, and tested by Bioviridian Inc.The laboratory’s original certificate lists American Peptides as the vendor. Look up the code at bioviridians.com to check it.
What researchers study it for
- How it interacts with IGF-binding proteins
- Growth of muscle cells in the dish
- Body growth in rats with diabetes
- Growth of the fetus in sheep
How it is thought to work
Like the natural hormone, it signals through the IGF-1 receptor. In the first cell experiments, its stronger activity in culture was explained by its much looser attachment to the IGF-binding proteins that usually control how much IGF-1 is free to act. The animal picture is not uniform: diabetic rats regained growth, while growth-restricted fetal sheep showed no improvement.
Where the research stands
Lab reagent with animal data; no human studies found. A narrative review published in 2026 could not locate any peer-reviewed research in people, and a ClinicalTrials.gov search turned up nothing registered.
Sources
- Francis GL, et al. (1992). Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency. Journal of Molecular Endocrinology.
- Tomas FM, et al. (1993). Insulin-like growth factor-I and more potent variants restore growth of diabetic rats without inducing all characteristic insulin effects. The Biochemical Journal.
- White A, et al. (2025). IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep. American Journal of Physiology. Endocrinology and Metabolism.
- Dominikowski A, et al. (2026). The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Frontiers in Endocrinology.
For laboratory research use only. Not a drug, food, supplement or cosmetic; not for human or veterinary use. Nothing on this page is medical advice or a usage guide.