CAS: 946870-92-4 · MW: ~9111 Da · Purity: ≥98% by reverse-phase HPLC · Format: 1 mg lyophilized · Endotoxin: <1 EU/mg (LAL) · Identity: ESI-MS confirmed

IGF-1 LR3 (Long Arg³ Insulin-like Growth Factor-1) is an 83-amino-acid recombinant analog of insulin-like growth factor 1, modified by an arginine substitution at position 3 and a 13-residue N-terminal extension. This research-grade IGF-1 LR3 peptide is supplied as a 1 mg lyophilized vial at ≥98% purity by reverse-phase HPLC, with third-party analytical verification of identity, purity, and endotoxin load for every manufactured lot.

For laboratory research use only. Not for human consumption, veterinary use, food, or therapeutic use. Not a drug, supplement, or cosmetic. Sold exclusively to qualified research professionals and institutions.

Structure & Identity

IGF-1 LR3 has been characterized in the published literature as a single-chain polypeptide of 83 amino acid residues. Researchers have described the molecule as differing from native IGF-1 in two ways: substitution of glutamic acid with arginine at position 3, and an additional 13-residue N-terminal sequence (MFPAMPLSSLFVN-) retained from the methionyl-porcine growth hormone fusion cassette used during E. coli expression. The peptide has an approximate molecular weight of 9111 Da. In the biochemical literature, these structural modifications have been described as reducing the affinity of the IGF-1 LR3 analog for the six insulin-like growth factor binding proteins (IGFBP-1 through IGFBP-6) relative to native IGF-1 [1,2].

Research Background

IGF-1 LR3 has been referenced across in vitro and animal-model studies examining the IGF-1 axis and its downstream signaling. Published research contexts for the LR3 analog include:

• IGF-1 receptor signaling. Investigated as a tool reagent in cultured cell lines (including L6 myoblasts and 3T3-L1 fibroblasts) for studies of IGF-1 receptor (IGF-1R) binding, autophosphorylation kinetics, and downstream PI3K/Akt and MAPK/ERK1/2 pathway engagement [1,3].
• Animal-model characterization. Referenced in rodent models examining nitrogen balance, protein turnover, and clearance kinetics of the LR3 analog versus native IGF-1 under defined experimental conditions [2].
• Bioprocess and cell-culture research. Characterized in the literature as a defined-medium component for hybridoma, CHO, and HEK293 cell line maintenance, where reduced IGFBP affinity is described as functionally relevant in serum-supplemented systems [2].

These references describe findings in non-human in vitro and animal systems and do not constitute claims about effects in humans.

Specifications

Storage & Handling

Lyophilized material is stable at -20°C for 24 months from date of manufacture when protected from light and moisture. Once reconstituted in laboratory buffer, the peptide should be aliquoted into low-binding polypropylene tubes and stored at -80°C. Repeated freeze-thaw cycles are not recommended; IGF-1 family peptides are susceptible to aggregation and oxidation of methionine residues. Handling should occur under aseptic conditions in a Class II biosafety cabinet or laminar flow hood. Standard laboratory PPE applies per institutional biosafety guidelines.

Quality Assurance

Every manufactured lot is accompanied by batch-specific analytical documentation including: third-party reverse-phase HPLC chromatogram, ESI-MS deconvoluted mass spectrum, LAL chromogenic endotoxin quantification, residual moisture by Karl Fischer titration, and SDS-PAGE single-band confirmation. Reference standards are maintained at -80°C and cross-validated against international IGF-1 reference preparations on a quarterly basis. Manufacturing occurs in ISO 9001-certified facilities under documented cGMP-aligned procedures.

This material is supplied exclusively to qualified research professionals, academic laboratories, contract research organizations, and institutional purchasing departments. Proof of institutional affiliation and a signed research-use acknowledgment may be requested prior to shipment.

For laboratory research use only. Not for human consumption, veterinary use, food, or therapeutic use. Not a drug, supplement, or cosmetic.

Frequently Asked Questions

What is IGF-1 LR3?

IGF-1 LR3 (Long Arg³ Insulin-like Growth Factor-1) is an 83-amino-acid recombinant analog of native human IGF-1, produced by E. coli expression. It carries an arginine substitution at residue 3 of the mature IGF-1 sequence and a 13-residue N-terminal extension. The CAS number is 946870-92-4 and the molecular weight is approximately 9111 Da.

How is IGF-1 LR3 different from native IGF-1?

IGF-1 LR3 differs from native IGF-1 in two ways: the Arg³ substitution and the N-terminal extension. The published literature describes these modifications as reducing the analog’s affinity for the IGF binding proteins (IGFBP-1 through IGFBP-6) relative to native IGF-1, while affinity for the IGF-1 receptor (IGF-1R) is preserved [1,2].

What is the molecular weight of IGF-1 LR3?

Approximately 9111 Da, with a molecular formula of C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉. Identity is confirmed lot-to-lot by ESI mass spectrometry.

What is the CAS number for IGF-1 LR3?

946870-92-4.

What purity is IGF-1 LR3 supplied at?

≥98% by reverse-phase HPLC. Each manufactured lot is third-party analyzed and accompanied by batch-specific documentation of HPLC purity, ESI-MS identity, LAL endotoxin load (<1 EU/mg), and residual moisture.

How should IGF-1 LR3 be stored?

Lyophilized vials are stable at -20°C for 24 months when protected from light and moisture. Once reconstituted in laboratory buffer, the peptide should be aliquoted into low-binding tubes and stored at -80°C. Repeated freeze-thaw cycles are not recommended.

How is IGF-1 LR3 reconstituted for laboratory work?

In a research-laboratory context, IGF-1 LR3 is soluble in dilute acetic acid (10 mM), dilute HCl, or sterile water. Researchers typically reconstitute in bacteriostatic water or PBS for in vitro experimental work, following standard aseptic technique.

Who can purchase IGF-1 LR3?

This material is supplied exclusively to qualified research professionals, academic laboratories, contract research organizations, and institutional purchasing departments. Proof of institutional affiliation and a signed research-use acknowledgment may be requested.

What is IGF-1 LR3 used for in research?

IGF-1 LR3 has been referenced in the peer-reviewed literature as a tool reagent for studying IGF-1 receptor signaling independent of IGFBP modulation, in animal-model research examining the IGF-1 axis, and in cell-culture media development. All published characterizations are in non-human in vitro or animal systems.

References

1. Francis GL, Ross M, Ballard FJ, Milner SJ, Senn C, McNeil KA, Wallace JC, King R, Wells JR. 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):213-23. PMID: 1379704
2. Tomas FM, Knowles SE, Owens PC, Chandler CS, Francis GL, Read LC, Ballard FJ. Increased weight gain, nitrogen retention and muscle protein synthesis following treatment of diabetic rats with insulin-like growth factor (IGF)-I and Long-R3-IGF-I. J Endocrinol. 1993;137(3):413-21. PMID: 8371074
3. Dupont J, Holzenberger M. Biology of insulin-like growth factors in development. Birth Defects Res C Embryo Today. 2003;69(4):257-71. PMID: 14745968
4. Coleman ME, DeMayo F, Yin KC, Lee HM, Geske R, Montgomery C, Schwartz RJ. Myogenic vector expression of insulin-like growth factor I stimulates muscle cell differentiation and myofiber hypertrophy in transgenic mice. J Biol Chem. 1995;270(20):12109-16. PMID: 7744859