IGF-1 LR3
IGF-1 LR3 (Long R3 IGF-I) is an 83-residue analogue of human insulin-like growth factor 1 with an Arg3 substitution and a 13-residue N-terminal extension, giving much lower binding to IGF-binding proteins.
- TypeProtein (83 residues)
- FormulaC400H619N111O115S9
- Average mass9111.45 g/mol
- Vesta listings2
Reference page for laboratory use · updated 2026-10-30
Overview
IGF-1 LR3 at a glance
The modifications reduce binding to IGF-binding proteins, so the analogue stays active in culture media where native IGF-1 would be sequestered. It is widely used as a growth-factor supplement in cell culture and has been expressed recombinantly in yeast.
Animal and cell studies use it as a more potent IGF-1 receptor agonist because it escapes sequestration by binding proteins.
Structure
The sequence has 83 residues and three disulfide bonds. The formula and masses in this page are calculated from the sequence registered in the FDA Global Substance Registration System, with three disulfides, because PubChem does not list a compound record.
Identity
Identity data
| Name | IGF-1 LR3 |
|---|---|
| Also written as | Long R3 IGF-I, LR3-IGF-1 |
| Type | Protein (83 residues) |
| Research area | Growth hormone axis peptides |
| Molecular formula | C400H619N111O115S9 |
| Monoisotopic mass | 9105.3487 Da |
| Average molecular weight | 9111.45 g/mol |
| Sequence | MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSA |
| Ring structure | 3 disulfide bonds |
| Registry record | FDA Global Substance Registration System, UNII M9L22Y19H9 |
The numbers are calculated from sequence. Reference data retrieved on 2026-10-30. Compare these values with the batch certificate of analysis, using the compound identity file template.
Expected values
Mass spectrometry reference
Ions calculated from the monoisotopic mass 9105.3487 Da. Use them to check an LC-MS result; for larger peptides the instrument usually reports a deconvoluted mass close to 9111.5 Da instead.
| Ion | m/z |
|---|---|
| [M+5H]5+ | 1822.0770 |
| [M+6H]6+ | 1518.5654 |
| [M+7H]7+ | 1301.7714 |
| [M+8H]8+ | 1139.1759 |
| [M+9H]9+ | 1012.7127 |
| [M+10H]10+ | 911.5421 |
For molecules of this size the tallest isotope peak is one to two mass units above the monoisotopic peak. Read the guide to average and monoisotopic mass for how these values are calculated.
Quality
Analytical notes for batch documents
- Correct disulfide pairing matters: misfolded isoforms have the same mass but different retention time, so a single HPLC peak and an intact-mass match should be reported together.
- At about 9.1 kDa the molecule is measured as a multiply charged envelope and reported as a deconvoluted average mass.
- Mass shifts to look for in this sequence: methionine oxidation (+15.995 Da, up to +31.990 Da for two); deamidation of Asn or Gln (+0.984 Da); a reduced disulfide (+2.016 Da).
- The molecular weight of a vial of powder includes counter-ions and water; the share of the powder that is peptide is the net peptide content.
Terms used on this page: Disulfide bond, Retention time, HPLC, Average mass.
Vesta listings
IGF-1 LR3 formats and prices
| Product | Per vial | SKU | Price per kit | Price per vial |
|---|---|---|---|---|
| IGF-1 LR3 | 1 mg | IG1 | $317.16 | $31.72 |
| IGF-1 LR3 | 100 mcg | IG01 | $54.10 | $5.41 |
Prices are per kit of 10 vials in US dollars. Shipping is paid by the customer and is shown in the cart. Volume savings of 5 %, 8 % and 10 % apply from $350.00, $600.00 and $1,000.00. See the full price list.
Published literature
Selected scientific literature
Bibliographic details were read from PubMed on 2026-10-30. The papers are listed for scientific reference; Vesta makes no claim about the use of its research materials in people or animals.
- Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastorisLu Z, Liu N, Huang H et al. · Appl Microbiol Biotechnol · 2023 · PMID 37261455
- Effects of insulin-like growth factor-I and its analogue, long-R3-IGF-I, on intestinal absorption of 3-O-methyl-D-glucose are less pronounced than gut mucosal growth responsesGarnaut SM, Howarth GS, Read LC et al. · Growth Factors · 2002 · PMID 11999215
Questions
Frequently asked questions
What is IGF-1 LR3?
IGF-1 LR3 (Long R3 IGF-I) is an 83-residue analogue of human insulin-like growth factor 1 with an Arg3 substitution and a 13-residue N-terminal extension, giving much lower binding to IGF-binding proteins.
What is the molecular weight of IGF-1 LR3?
IGF-1 LR3 has the formula C400H619N111O115S9, an average molecular weight of 9111.45 g/mol and a monoisotopic mass of 9105.3487 Da. A salt form, a different counter-ion or a metal complex changes the molecular weight printed on a certificate of analysis, so compare like with like.
How can I check the identity of a batch of IGF-1 LR3?
Compare the intact mass measured by LC-MS with the expected values on this page, for example [M+6H]6+ at m/z 1518.5654. Confirm that one main HPLC peak carries that mass and that the batch code on the report matches the vial. The guides on mass spectrometry and on certificates of analysis explain each step.
Which IGF-1 LR3 products does Vesta list?
Vesta lists 2 products for IGF-1 LR3: 100 mcg, 1 mg per vial in kits of 10 vials. Prices are shown per kit in US dollars, and shipping is paid by the customer.