IGF-1 LR3: Research Overview and Structure
Quick Answer
IGF-1 LR3 (Long R3 IGF-I) is an 83-residue analogue of insulin-like growth factor 1. It carries an arginine in place of glutamate at position 3 and a 13-residue N-terminal extension, changes that lower its binding to IGF-binding proteins. It is studied in IGF-1 receptor signaling and is widely used as a cell-culture media supplement.
Key Takeaways
- 83 residues: the 70-residue IGF-1 chain plus a 13-residue N-terminal extension.
- Glu3 is replaced by Arg (the “R3” in the name).
- Reduced affinity for IGF-binding proteins compared with native IGF-1.
- A common supplement in serum-free cell-culture media.
Identifiers
| Field | Value |
|---|---|
| Other names | Long R3 IGF-I, LR3-IGF-1 |
| Length | 83 amino acids |
| Parent protein | Insulin-like growth factor 1 (70 residues) |
| Modifications | Glu3→Arg substitution; 13-residue N-terminal extension |
| Molecular weight | See the batch COA (measured by mass spectrometry) |
| Form | Lyophilized solid, sealed vial |
Why the Modifications Matter
In culture media and serum, native IGF-1 is largely held by IGF-binding proteins. The Arg3 substitution and the N-terminal extension reduce that binding, so more of the analogue stays free to engage the IGF-1 receptor in vitro. That property is why it became a standard media supplement for cell lines.
Research Areas
- IGF-1 receptor signaling
- Cell proliferation in culture (a common cell-culture media supplement)
Related guides: Tesamorelin vs CJC-1295.
Storage of the Sealed Vial
The compound ships as a lyophilized (freeze-dried) solid in a sealed vial labelled with its lot number. Store sealed vials as stated on the label, protected from light and moisture; see our storage and handling guide for temperature ranges.
Analytical Verification and Documentation
Each lot is tested by Testides, an independent laboratory, for HPLC purity and content, and the certificate is published with its report number so it can be checked against the lab’s record: IGF-1 LR3 1 mg certificate. New to certificates? Read how to read a COA.
Frequently Asked Questions
What is IGF-1 LR3?
IGF-1 LR3 is an 83-residue analogue of insulin-like growth factor 1 with an Arg3 substitution and a 13-residue N-terminal extension.
What does LR3 stand for?
“Long” refers to the 13-residue N-terminal extension and “R3” to the arginine at position 3.
How is IGF-1 LR3 different from IGF-1?
It binds IGF-binding proteins far less than native IGF-1, so more remains free to engage the IGF-1 receptor in cell culture.
What is the molecular weight of IGF-1 LR3?
The batch COA reports the measured mass for each lot.
Sold for in-vitro laboratory research only. Not for human or animal use and not for diagnostic or therapeutic procedures. Nothing here describes or suggests use in people.
For Research Use Only. Not for use in diagnostic or therapeutic procedures.
