What is IGF-1 LR3, and what is it studied for?
IGF-1 LR3, Long R3 IGF-1, is an 83-residue recombinant analogue of insulin-like growth factor 1: the 70-residue hormone with arginine replacing glutamate at position 3 and a 13-residue N-terminal extension. The changes reduce binding to IGF-binding proteins, which is why it is used in cell culture as a more potent IGF-1 receptor agonist. No CAS number or PubChem record is on file here.
What is the structure of IGF-1 LR3?
A single-chain protein of 83 residues with three disulfide bonds, produced recombinantly rather than by solid-phase synthesis. The Arg3 substitution and the extension are what distinguish it from native IGF-1 and from Long IGF-1 without the substitution. Mass is about 9.1 kDa by the literature; the product page leaves the formula and CAS fields blank because no registry record has been confirmed.
| Identifier | Value |
|---|---|
| Molecular formula | not recorded |
| Molecular weight | not recorded |
| Residues | not recorded |
| CAS number | not recorded |
| PubChem CID | not recorded |
| Current lot | IGF1-0803 |
How is IGF-1 LR3 thought to work?
Agonist at the IGF-1 receptor, a receptor tyrosine kinase, activating PI3K/Akt and MAPK signalling. Francis and colleagues showed in 1992 that reduced affinity for IGF-binding proteins left more free analogue available to the receptor, giving greater potency than IGF-1 in cell assays.
Which research areas use IGF-1 LR3?
| Area | Typical models and endpoints |
|---|---|
| Cell-culture supplementation | Serum-free media where IGF-1 receptor signalling supports proliferation. |
| IGF-1 receptor signalling | Phosphorylation readouts for Akt and ERK pathways. |
| Binding-protein studies | Comparison with native IGF-1 to measure the effect of IGFBP sequestration. |
| Protein characterisation | A disulfide-bonded recombinant protein used in intact-mass and reduction studies. |
What does the published literature show?
Francis et al. (Journal of Molecular Endocrinology, 1992) described the fusion-protein analogues and the relative importance of binding-protein and receptor binding for potency. The analogue is widely used as a cell-culture reagent; there is no clinical programme for it. Research use is in-vitro and preclinical.
How is IGF-1 LR3 handled in the laboratory?
Reconstitute gently; proteins denature with vigorous shaking. Three disulfide bonds mean reducing agents must be avoided in diluents. Store lyophilized at minus 20 °C, aliquot solutions once, and avoid repeated freeze-thaw, which aggregates proteins more readily than short peptides. The concentration table covers volumes and syringe units; the storage guide covers stability by compound class.
What does the current certificate show?
Lot IGF1-0803 tested at 99.55% purity by RP-HPLC (214 nm), identity confirmed by LC-MS/MS, endotoxin <0.05 EU/mL. The certificate is in the COA library and the lot number on the vial matches it. Sold as 1 mg per vial at $85, for laboratory research only.
Certificate history for IGF-1 LR3
Every certificate the library holds for this compound, newest first. A replaced lot stays listed so the history can be read; the certificate dataset reads all 114 together.
| Lot | Issued | Size | Identity | Purity | Content | Status |
|---|---|---|---|---|---|---|
| IGF1-0803 | Aug 17, 2026 | 1 mg | LC-MS/MS | 99.55% | 1.12 mg | Current |
| IGF-0528 | Jun 17, 2026 | 1 mg | MALDI-MS | 99.9% | 1.21 mg | Replaced |
Frequently asked questions
How does LR3 differ from native IGF-1?
By an Arg3 substitution and a 13-residue N-terminal extension, which together lower affinity for IGF-binding proteins and raise effective potency in cell assays.
What does the current certificate show?
Lot IGF1-0803: identity by LC-MS/MS, purity 99.55% by RP-HPLC at 214 nm, content 1.12 mg against a 1 mg label, endotoxin below 0.05 EU/mL. Issued 17 August 2026.
Why is the vial 1 mg?
Because a 9 kDa protein used at nanogram-per-millilitre concentrations in culture is consumed in far smaller mass quantities than a short peptide.
References
- Francis GL, Ross M, Ballard FJ, et al. 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. J Mol Endocrinol. 1992;8(3):213-223.
Clinical results cited above describe regulated trials of pharmaceutical products and are given as context for research interest only. Nothing on this page describes or recommends use of the material sold here in humans or animals.
IGF-1 LR3 1 mg
$85 per vial
Lot IGF1-0803 · 99.55% RP-HPLC (214 nm) · certificate published
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