IGF-1 LR3 Pen
Long R3 IGF-1, the 83-residue IGF-1 analogue, in bacteriostatic water at 1 mg/mL, 3 mg per 3 mL pen. Filled from a protein lot tested in the manufacturer’s own laboratory, with a certificate.
| Compound | IGF-1 LR3 Long R3 IGF-1; recombinant human IGF-1 analogue with a 13-residue N-terminal extension and Glu3→Arg |
|---|---|
| CAS number | 143045-27-6 |
| Molecular formula | C 400 H 625 N 111 O 115 S 9 (reduced-chain calculation) |
| Theoretical mass | 9117.6 Da (reduced-chain calculation; 9111.6 Da with the three disulfides formed) |
| Sequence / structure | H-MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSA-OH (83 residues; three intrachain disulfides; free N- and C-termini) |
| Contents | IGF-1 LR3: 3 mg per 3 mL pen (0.1% w/v) |
| Form | Sterile aqueous solution in bacteriostatic water (0.9% benzyl alcohol), supplied in a 3 mL glass cartridge inside a preloaded autoinjector pen fitted with a needle |
| Storage, sealed | Store at 2–8 °C in the original carton, protected from light |
| Format | Solution in a 3 mL pre-filled pen |
Sizes and lots
- 3 mg · 1 pen — $68.99
- 3 mg · Kit of 10 — $613.32
IGF-1 LR3 is Long R3 IGF-1, an 83-residue analogue of human insulin-like growth factor 1 built with a 13-residue N-terminal extension and arginine at position 3 so that it binds IGF-binding proteins weakly. This listing is a preloaded autoinjector pen: 3 mg of the protein dissolved in 3 mL of bacteriostatic water. Research on it comes from cell culture and rat studies of IGF-I potency and binding-protein interactions.
What is in the pen
Each pen carries a 3 mL glass cartridge of sterile solution with IGF-1 LR3 at 0.1% w/v, which is 1 mg/mL and 3 mg per pen. At the certificate's folded mass of 9111.6 Da, 1 mg/mL is about 0.11 mM. The diluent is bacteriostatic water with 0.9% benzyl alcohol. The safety data sheet does not classify the protein as hazardous; benzyl alcohol is listed as harmful if swallowed or inhaled, an eye irritant and a possible skin sensitiser. Storage follows the safety data sheet: keep the pen at 2 to 8 °C in its carton, away from light, capped once in use, and never frozen. Discard a pen whose solution has frozen, discoloured or become cloudy. The IGF-1 LR3 1 mg vial holds the same protein freeze-dried, and peptide pen vs vial compares the two formats.
What the research covers
Long R3 IGF-I was first made in Escherichia coli as a fusion protein, with a 13-residue lead made of methionyl porcine growth hormone's first 11 amino acids plus Val-Asn, and arginine replacing glutamate 31. The extension seemed to help the chain fold correctly during production, and in L6 myoblasts the long analogues outperformed authentic IGF-I1. The design is aimed at the IGF-binding proteins, a family of six related proteins that bind IGF-I and IGF-II tightly and can block IGF action2.
In a 14-day rat study, LR3IGF-I, which the authors described as binding those proteins very weakly, was substantially more potent than IGF-I on body weight gain, nitrogen retention and food conversion, while body proportions stayed broadly as they were3. Growth hormone tested alongside did not stimulate growth3.
Frequently asked questions
How does the pen differ from the 1 mg vial?
The vial is 1 mg of freeze-dried protein stored at −20 °C until a laboratory dissolves it. The pen holds 3 mg already in bacteriostatic water at 1 mg/mL and is stored at 2 to 8 °C. The protein, Long R3 IGF-1, is the same in both.
Why must the pen never be frozen?
The safety data sheet says not to freeze it and to discard a pen whose solution has frozen. IGF-1 LR3 is a folded protein held together by three disulfides, and even the dry protein's certificate warns against repeated freeze-thaw cycles.
References
- Francis GL, Ross M, Ballard FJ, et al. 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. DOI · PubMed
- Baxter RC. Insulin-like growth factor (IGF)-binding proteins: interactions with IGFs and intrinsic bioactivities. Am J Physiol Endocrinol Metab. 2000;278(6):E967-76. DOI · PubMed
- Tomas FM, Knowles SE, Chandler CS, et al. Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats. J Endocrinol. 1993;137(3):413-21. DOI · PubMed
For laboratory research use only. Not for human or veterinary consumption. Products have not been evaluated by the U.S. Food and Drug Administration and are not intended to diagnose, treat, cure or prevent any disease.