# IGF-1 LR3

> Long R3 IGF-1 — 83-residue recombinant analogue with weak IGFBP binding

All products are sold strictly for laboratory research use only. Not for human or veterinary use.

- Web page: https://peptidemedixeu.com/en/products/igf-1-lr3/
- Brand: Peptide Medix EU
- Category: [IGF & Muscle Peptides](https://peptidemedixeu.com/en/collections/igf-peptides/)
- Purity: ≥99% by HPLC; lot-matched COA available
- CAS number: 946870-92-4
- from €34 (EUR)

## Sizes and prices (EUR)

| Size | Price | SKU |
| --- | --- | --- |
| 0.1 mg | €34 | IGF-1-LR3-0-1-MG |
| 1 mg | €85 | IGF-1-LR3-1-MG |

_Catalog prices at build time; the web page and checkout are authoritative._

## Specifications

- **CAS number:** 946870-92-4
- **Molecular formula:** C400H625N111O115S9
- **Molecular weight:** 9117.60 g/mol
- **Chain length:** 83 amino acids (70-residue IGF-1 core plus 13-residue N-terminal extension)
- **Form:** Lyophilized powder, sealed glass vial
- **Purity:** ≥99% by HPLC; lot-matched COA available
- **Available sizes:** 0.1 mg, 1 mg
- **Storage (lyophilized):** −20 °C or below, sealed and protected from light and moisture
- **Also known as:** Long R3 IGF-1, LR3 IGF-1
- **Key modifications:** Arg substituted for Glu at position 3; N-terminal 13-residue extension
- **Protein class:** Recombinant insulin-like growth factor analogue
- **Primary target:** IGF-1 receptor (IGF-1R), a receptor tyrosine kinase
- **Research areas:** IGF-1R signalling, myoblast and cell proliferation assays, serum-free culture

## Description

IGF-1 LR3 — short for Long R3 insulin-like growth factor 1 — is a recombinant analogue of human IGF-1 with 83 amino acids, defined by two engineered changes: position 3 carries arginine where the natural protein has glutamate, and an extra stretch of 13 residues is added to the N-terminus. Together these raise the molecular weight to about 9118 g/mol and, more importantly, greatly weaken binding to the IGF binding proteins, which in the blood normally hold on to more than 95% of IGF-1.

Vials contain 0.1 mg or 1 mg — small by our standards, because cell culture uses it at nanomolar levels and one milligram covers an enormous number of plates. With a molecular weight of 9117.60 g/mol, 1 mg equals about 110 nanomoles; dissolved in 1 mL that makes a stock of around 110 micromolar, which is then diluted several thousand times. At these working levels, noticeable amounts stick to plastic tubes and pipette tips, so dilute stocks are usually made up with a carrier protein — commonly 0.1% bovine serum albumin. Published use is mainly in culture with little or no serum, in proliferation assays with myoblasts and other cells, and in studies of IGF-1 receptor signalling where binding proteins from serum would otherwise distort the results.

## Frequently asked questions

### What is IGF-1 LR3?

A recombinant version of IGF-1 (insulin-like growth factor 1) with 83 amino acids, carrying arginine at position 3 and an extra 13-residue stretch at the N-terminus. Both changes reduce binding to IGF binding proteins, making it a dependable way to activate the IGF-1 receptor in cell culture.

### LR3 or DES(1-3) — how do they differ?

Each escapes IGF binding proteins, but by a different route: DES(1-3) lacks the first three N-terminal residues, while LR3 has arginine in position 3 plus an extension. LR3 is the larger molecule and is typically described as remaining stable for longer.

### Do you provide a Certificate of Analysis?

Yes. An independent lab HPLC-tests each lot for identity and ≥99% purity, and the matching certificate can be requested. Compare its lot number with your vial before adding the material to your lab records.

### Why add a carrier protein?

At the low concentrations used in cell culture, proteins stick to plastic tubes and tips, quietly reducing the dose that reaches your cells. A carrier such as 0.1% BSA in dilute working stocks coats those surfaces and keeps the concentration where you intended it.

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All products offered on this website are intended solely for in-vitro laboratory research and development by qualified professionals. They are not drugs, foods, cosmetics or dietary supplements, and are not intended to diagnose, treat, cure or prevent any disease. Products must not be introduced into humans or animals in any manner. By purchasing, you confirm that you are a qualified researcher and accept full responsibility for handling and storage in accordance with applicable laws.

Peptide Medix EU · https://peptidemedixeu.com/en/products/igf-1-lr3/