IGF-1 LR3, or Long R3 IGF-1, is a synthetic 83-amino-acid analogue of human insulin-like growth factor 1, incorporating a 13-amino-acid extension of the B-domain and a single substitution of arginine for glutamic acid at position 3. AminoOptimization Group supplies it as a lyophilised research powder in a 1 mg presentation, tested to 99% purity by HPLC, with a Certificate of Analysis available for the lot supplied. This material is offered strictly for laboratory research use. It is not a drug, and it is not for human or veterinary use.
What is IGF-1 LR3?
Native IGF-1 is a 70-amino-acid single-chain polypeptide with substantial sequence homology to proinsulin, and its activity in circulation is closely regulated by a family of six IGF binding proteins (IGFBPs). Long R3 IGF-1 modifies the parent molecule at the points that matter to that regulation: the 13-residue N-terminal extension of the B-domain adds length, and the Arg3-for-Glu3 substitution alters a residue implicated in IGFBP recognition. Published characterisation reports substantially reduced affinity for all known IGFBPs relative to native IGF-1, while binding to the IGF-1 receptor is preserved.
This combination of properties is why Long R3 IGF-1 was developed, and remains characterised in the literature, as a cell-culture reagent rather than a circulating-hormone analogue. Because it is not efficiently sequestered by IGFBPs present in serum or culture media, it is described as producing more consistent, unbound engagement of the IGF-1 receptor in vitro than native IGF-1 at an equivalent concentration — a property that has made it a reference reagent in serum-free media formulations used in growth factor signalling studies.
At 9117.60 g/mol, IGF-1 LR3 is substantially larger than the growth-hormone secretagogues and GHRH fragments often studied alongside it, reflecting its status as a full single-chain protein rather than a short synthetic peptide. Its receptor pharmacology sits at the intersection of the IGF-1 receptor and insulin receptor families, which cross-react at higher concentrations — a point often addressed in study designs using IGF-1 LR3 to isolate IGF-1-receptor-specific signalling from insulin-receptor-mediated effects.
Specifications
- Compound: IGF-1 LR3 (Long R3 IGF-1)
- CAS number: 946870-92-4
- Molecular formula: C400H625N111O115S9
- Molecular weight: 9117.60 g/mol
- Purity: 99% HPLC
- Presentation: Lyophilised powder, sealed vial
- Available sizes: 1 mg
- Physical form: White to off-white powder
- Classification: Research peptide — not for human or veterinary use
Research context
IGF-1 LR3 is studied predominantly in cell-based and in vitro systems as a means of achieving more uniform IGF-1 receptor engagement than native IGF-1 permits. Published research examines how IGF-1 receptor activation initiates PI3K/Akt and Ras/MAPK signalling, and how the reduced IGFBP affinity of the Long R3 analogue changes the kinetics of that activation relative to native ligand in the same system.
It appears frequently in study designs involving myoblast and other proliferative cell lines, where it is used to probe growth factor signalling and receptor cross-talk between the IGF-1 receptor and the insulin receptor. Its resistance to IGFBP sequestration also makes it a tool for characterising the binding proteins themselves, since a ligand a given IGFBP cannot bind serves as a control for that protein’s contribution to an observed result.
None of this literature establishes safety or efficacy for use in humans. It is provided as research context only.
Reconstitution
Lyophilised protein requires reconstitution with a suitable sterile diluent before use in solution. Bacteriostatic water is the diluent most commonly specified for multi-use laboratory preparations; sterile water is typical for single-use work.
Direct the diluent stream against the inner wall of the vial rather than onto the powder itself, and allow the material to dissolve without agitation. As a full single-chain protein, IGF-1 LR3 is susceptible to shear stress — do not shake the vial. Swirl gently if needed, and expect full dissolution within a few minutes at room temperature.
Working concentration is a function of how much diluent is added to a given vial mass. Our peptide reconstitution calculator computes the resulting concentration for any combination of vial size and diluent volume.
Storage and stability
Before reconstitution: store the sealed vial in a freezer at -20 °C, protected from light. Lyophilised protein is comparatively stable in this state, and brief shipping excursions to ambient temperature are normal and not expected to compromise a properly lyophilised product.
After reconstitution: refrigerate at 2–8 °C and protect from light. Reconstituted IGF-1 LR3 in dilute solution is reported to be prone to loss through adsorption to vial and tubing surfaces; some protocols address this with a carrier protein in the diluent. Avoid repeated freeze-thaw cycles, a well-documented cause of aggregation and loss of measurable activity — aliquot instead if repeated sampling is required.
Inspect solutions before use. Cloudiness, visible particulate, or discolouration indicate the material should not be relied upon for quantitative work.
Certificate of Analysis
Every lot is tested by high-performance liquid chromatography, and the purity figure shown above refers to analytical results for the specific lot supplied — not to a generic specification. A Certificate of Analysis is available on request, including before purchase if your protocol requires it.
Purity by HPLC describes the proportion of the target protein relative to detectable related substances. It is a statement about the material as manufactured and tested — expressly not a representation that it is suitable for use in humans or animals.
Handling and safety
Handle in accordance with good laboratory practice. Use appropriate personal protective equipment, work in a suitable containment environment, and dispose of material and consumables per institutional and local regulatory requirements. Anyone with access to this material should understand that it is not for human or veterinary use.
Frequently asked questions
What distinguishes IGF-1 LR3 from native IGF-1?
The Long R3 analogue carries a 13-amino-acid extension of the B-domain and an arginine substitution at position 3 relative to native IGF-1. Together these changes are reported to substantially reduce binding to IGF binding proteins while preserving affinity for the IGF-1 receptor, which is why it is characterised as producing more consistent, unbound engagement in cell-based systems.
Is IGF-1 LR3 approved in Canada?
No. This compound has not been evaluated or authorised by Health Canada, the FDA, or any comparable regulatory authority. It carries no DIN or NPN, its safety and efficacy for human use have not been assessed, and it is supplied for laboratory research only.
How much diluent should be used?
That depends on the working concentration your protocol requires. Use the reconstitution calculator to work out the resulting concentration for your vial size.
How stable is IGF-1 LR3 once reconstituted?
Stability in solution is shorter than in lyophilised form and is further affected by dilution and surface adsorption. Refrigerate at 2–8 °C, protect from light, avoid freeze-thaw cycling, and validate stability under your own storage conditions if your work depends on it.
Do you provide a Certificate of Analysis?
Yes — lot-specific, available on request, including before purchase.
Research use only
This product is supplied solely for laboratory and scientific research. It is not a drug, food, cosmetic, or medical device, and it must not be administered to humans or animals. Nothing on this page is medical advice or a therapeutic claim. Full terms are set out in our Research Use Only Disclaimer.
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