IGF-1 LR3 (Long R3 IGF-1)

What is IGF-1 LR3?

IGF-1 LR3 is an 83-amino-acid synthetic analogue of human insulin-like growth factor-1 (IGF-1) in which glutamic acid at position 3 is replaced by arginine and a 13-residue extension is added to the N-terminus. These changes markedly reduce its affinity for the IGF-binding proteins (IGFBPs) while retaining activity at the type 1 IGF receptor (IGF-1R).

Native IGF-1 is a 70-amino-acid hormone produced mainly by the liver in response to growth hormone. Because most circulating IGF-1 is sequestered by IGFBPs, researchers developed IGF-1 LR3 as a longer-acting, more stable tool for cell-culture and animal work. It is one of the most widely used IGF-1 analogues in laboratory studies of growth-factor signalling.

GenoPept supplies IGF-1 LR3 to UK laboratories as a lyophilised powder in 0.1mg and 1mg vials, each batch verified at ≥99% purity with a third-party Certificate of Analysis.

IGF-1 LR3 research applications

Published research uses IGF-1 LR3 as a reference IGF-1R agonist across several model systems. Typical areas of investigation include:

• Skeletal muscle cell biology – IGF-1 LR3 is studied in myoblast and myotube cultures to examine proliferation, differentiation and protein synthesis signalling.
• Cell-culture media supplementation – it is used in serum-free and recombinant protein production systems as a mitogenic supplement, taking advantage of its low IGFBP binding.
• Growth-factor receptor signalling – research explores IGF-1R phosphorylation, PI3K/Akt/mTOR and MAPK pathway activation, and cross-talk with the insulin receptor.
• Neuroscience and tissue models – IGF-1 LR3 has been investigated in neuronal survival assays and in animal models of tissue repair and metabolic regulation.
• Comparative analogue studies – it serves as a benchmark when characterising other IGF-1 variants such as IGF-1 DES(1-3) or MGF.

Mechanism of action (preclinical)

IGF-1 LR3 binds the IGF-1 receptor, a transmembrane tyrosine kinase, triggering autophosphorylation and recruitment of IRS-1 and Shc adaptor proteins. Downstream signalling proceeds through the PI3K/Akt/mTOR axis, associated with protein synthesis and cell survival, and the Ras/MAPK cascade, associated with proliferation.

The Arg3 substitution and N-terminal extension reduce IGFBP binding, so a larger fraction of IGF-1 LR3 remains free to engage the receptor in vitro. In preclinical work this translates to greater potency than native IGF-1 on a molar basis and a longer effective duration in culture systems.

IGF-1 LR3 product specifications

Each vial is supplied to the specification below. Rows are limited to values that can be verified from published sources.

Available sizes

• IGF-1 LR3 0.1mg vial, lyophilised powder
• IGF-1 LR3 1mg vial, lyophilised powder

Bulk and wholesale boxes of 10 vials of IGF-1 LR3 save 20–50% for laboratories running larger studies; see the bulk and wholesale page. Free UK delivery applies to orders of £200 or more.

Reconstitution, handling and storage (laboratory)

IGF-1 LR3 is shipped as a lyophilised powder and should be stored unopened at –20 °C for long-term laboratory storage, or at 2–8 °C for short periods, protected from light. Allow the sealed vial to reach room temperature before opening to avoid condensation on the powder.

To reconstitute, add bacteriostatic water or another sterile diluent slowly down the inside wall of the vial, then swirl gently until dissolved. Never shake, as shear stress can denature the peptide. Because the molecule is a folded protein with three disulfide bonds, avoid vigorous mixing and repeated freeze–thaw cycles. After reconstitution keep the solution at 2–8 °C and use it within the period defined in your laboratory protocol.

Full step-by-step guidance is available in our articles on how to reconstitute research peptides and how to store research peptides. Handle with gloves and standard laboratory precautions.

Quality assurance and Certificate of Analysis

Every batch of IGF-1 LR3 is tested by an independent third-party laboratory (Puralytix, ISO/IEC 17025 accredited). Purity is confirmed by HPLC at ≥99% and identity is confirmed by LC-MS, so the material in the vial matches the label.

A batch-specific Certificate of Analysis is available through the “View Certificate of Analysis” button on this page, and the complete library is published in the COA library. Our guide to what a Certificate of Analysis shows explains how to read the chromatogram and mass spectrum. Vials are batch-identified with lot number and expiry, and orders are dispatched discreetly by tracked Royal Mail Special Delivery within the UK.

Related research compounds

• IGF-1 DES(1-3) 2mg – the truncated IGF-1 variant, often compared with IGF-1 LR3 in receptor-binding studies
• MGF 2mg – the IGF-1 splice-variant peptide studied alongside IGF-1 LR3 in muscle cell models
• PEG-MGF 2mg – pegylated MGF for extended-duration in-vitro protocols
• CJC-1295 + Ipamorelin Blend – growth hormone secretagogues for upstream GH/IGF axis research

IGF-1 LR3 frequently asked questions

What is IGF-1 LR3 used for in research?

IGF-1 LR3 is used as a stable IGF-1 receptor agonist in cell-culture and animal studies of growth-factor signalling. Researchers apply it in myoblast proliferation and differentiation assays, serum-free media supplementation, PI3K/Akt and MAPK pathway studies and comparative work with other IGF-1 analogues. All GenoPept material is for in-vitro laboratory research only.

How is IGF-1 LR3 supplied and what purity is it?

GenoPept supplies IGF-1 LR3 as a lyophilised powder in sealed, sterile glass vials of 0.1mg or 1mg. Each batch is verified at ≥99% purity by HPLC and confirmed for identity by LC-MS at an independent ISO/IEC 17025 laboratory, and a batch Certificate of Analysis is available on the product page and in the COA library.

How should IGF-1 LR3 be stored?

Store unopened IGF-1 LR3 vials at –20 °C for long-term storage, or at 2–8 °C for short periods, protected from light. After reconstitution with bacteriostatic water keep the solution refrigerated at 2–8 °C, avoid freeze–thaw cycles and use within the period stated in your laboratory protocol.

Is IGF-1 LR3 for human use?

No. IGF-1 LR3 is sold strictly for in-vitro laboratory research. It is not a medicine, is not approved for human or veterinary use and is not intended for diagnostic or therapeutic purposes. Our research use only policy applies to every order, and UK buyers should review it before purchasing.

What is the difference between IGF-1 LR3 and IGF-1 DES(1-3)?

IGF-1 LR3 is an 83-amino-acid analogue with an Arg3 substitution and a 13-residue N-terminal extension, whereas IGF-1 DES(1-3) is a 67-amino-acid form with the first three residues removed. Both show reduced IGFBP binding, but IGF-1 LR3 is generally reported to have the longer duration in culture, while DES(1-3) is studied for higher local potency.

Research use only. This product is supplied strictly for in-vitro laboratory research. It is not for human or veterinary use, not a medicine, and not for diagnostic or therapeutic use. Read the GenoPept research use only policy before ordering.