What Is IGF-1 LR3? Long R3 IGF-1 Explained
IGF-1 LR3 is an 83-amino-acid, long-acting version of IGF-1 developed in Adelaide. Two changes stop it being switched off by binding proteins. It is one of the most widely used growth factors in cell culture.
IGF-1 LR3 at a glance
IGF-1 LR3 (Long R3 IGF-1, also written LR3 IGF) is a modified version of insulin-like growth factor 1 (IGF-1), the hormone made mainly by the liver in response to growth hormone. It was developed by the Adelaide company GroPep in the early 1990s and is widely used as a growth factor in cell culture and biomanufacturing.
- Length
- 83 amino acids
- Natural IGF-1
- 70 amino acids
- Key changes
- Arg at position 3 + 13-residue extension
- Developed
- GroPep, Adelaide
- Our vial
- 1mg
- IGF-1 LR383
- Natural IGF-170
The two changes
| Change | What it does |
|---|---|
| R3: glutamic acid at position 3 swapped to arginine | Greatly reduces binding to IGF binding proteins |
| Long: 13 extra amino acids at the start | Further reduces binding and adds stability |
In the body, most IGF-1 is held by IGF binding proteins (IGFBPs), which keep it inactive. Because LR3 barely binds them, far more of it stays free and active, and for longer. That is why it is far more potent than natural IGF-1 in cell culture.
Where it sits on the GH axis
Unlike CJC-1295, tesamorelin and ipamorelin, which act on the pituitary to release growth hormone, IGF-1 LR3 acts downstream at the IGF-1 receptor itself. See the GH-axis comparison for the full map.
Uses in research
- Cell culture media supplement for growing mammalian cells.
- Biomanufacturing, where it supports cell lines that produce proteins.
- Research into IGF-1 receptor signalling.
Handling
IGF-1 LR3 is often reconstituted in a weak acid solution rather than plain bac water, and it is supplied in small amounts (we stock 1mg vials), so measure carefully. Store cold and away from light.
Further reading
For laboratory research use only. Not for human consumption. Not medical or legal advice.
