Insulin-like Growth Factor Analog
IGF-1 LR3 (Long R3 IGF-1) Research Peptide
IGF-1 LR3 (Long R3 Insulin-like Growth Factor 1, CAS 946870-92-4) is an 83-amino-acid synthetic analog of human IGF-1. Incorporating a 13-amino-acid N-terminal extension and an Glu3→Arg substitution in the mature IGF-1 sequence, it has substantially reduced affinity for IGF binding proteins (IGFBPs) compared to native IGF-1, resulting in a higher proportion of free (unbound) peptide in solution and an extended plasma half-life.
Compound identity
- Name
- IGF-1 LR3
- Class
- Insulin-like Growth Factor Analog
- CAS number
- 946870-92-4
- Also known as
- Long R3 IGF-1, Insulin-like Growth Factor 1 Long R3, IGF-1 Long R3
- Sequence
- Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn-[IGF-1 Glu3Arg variant, 70 aa]
Research context
IGF-1 LR3 (CAS 946870-92-4, MW approximately 9117 Da) is an 83-amino-acid recombinant analog of human IGF-1 comprising two structural modifications relative to the 70-aa native sequence: (1) a 13-amino-acid N-terminal extension (Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn-) that confers the 'Long' designation; and (2) a Glu3→Arg point mutation at position 3 of the mature IGF-1 sequence ('R3'). The Glu3→Arg substitution dramatically reduces IGF-1 LR3's affinity for all six classes of IGF binding proteins (IGFBP-1 through IGFBP-6) — the IGFBPs normally sequester the majority of circulating IGF-1, reducing its effective free concentration. The reduced IGFBP binding means that a higher fraction of IGF-1 LR3 remains free and receptor-accessible, and contributes to its longer effective half-life compared to native IGF-1 (which has a plasma half-life of approximately 10-20 minutes when free; IGF-1 LR3 has an effective half-life estimated at 20-30 hours in research models). Despite these modifications, IGF-1 LR3 retains full affinity for the IGF-1 receptor (IGF-1R) and the insulin receptor.
Research with IGF-1 LR3 spans muscle biology, cancer biology, metabolic research, and receptor pharmacology. In skeletal muscle cell culture models (L6, C2C12), IGF-1 LR3 stimulates PI3K/Akt/mTOR signaling, glucose uptake, and protein synthesis at lower concentrations than native IGF-1, owing to the reduced IGFBP sequestration. In oncology research, the IGF-1R is overexpressed in many cancer cell lines, and IGF-1 LR3 is a widely used tool compound for studying IGF-1R-driven proliferation and resistance to IGF-1R-targeted therapeutics. The compound's extended receptor engagement window (compared to native IGF-1) also makes it valuable for studying sustained IGF-1R signaling kinetics versus the more transient native-IGF-1 pulse. Long-term IGF-1 LR3 exposure studies in rodent models have examined effects on body composition, organ weight, and metabolic parameters.
As a research reagent, IGF-1 LR3 is used in cell culture, receptor pharmacology assays, and in-vivo preclinical models studying the IGF axis. DMV Research supplies IGF-1 LR3 as a lyophilized powder with per-batch third-party Certificate of Analysis confirming identity by mass spectrometry and purity by HPLC to 99%+.
Frequently asked questions
What is IGF-1 LR3?+
IGF-1 LR3 (Long R3 IGF-1, CAS 946870-92-4) is an 83-amino-acid synthetic analog of human IGF-1. It incorporates a 13-amino-acid N-terminal extension ('Long') and a Glu3→Arg point mutation ('R3') that dramatically reduces binding to IGF binding proteins (IGFBPs), resulting in a higher free fraction, extended effective half-life (~20-30 hours in research models vs ~10-20 minutes for free native IGF-1), and full retention of IGF-1 receptor affinity.
What is the difference between IGF-1 LR3 and native IGF-1?+
Native IGF-1 (CAS 67763-96-6) is a 70-amino-acid peptide, and the majority of circulating IGF-1 is bound to IGF binding proteins (IGFBPs), leaving only a small free fraction active at the IGF-1 receptor. IGF-1 LR3 (CAS 946870-92-4) has ~95% reduced affinity for IGFBPs due to the Glu3→Arg substitution, so a much higher proportion is free and receptor-accessible. The N-terminal extension further extends its plasma half-life. Both compounds retain full IGF-1 receptor binding affinity.
What is the difference between IGF-1 LR3 and IGF-1 DES?+
IGF-1 DES (des(1-3)-IGF-1) is a truncated form of IGF-1 lacking the first three N-terminal amino acids. Like LR3, DES IGF-1 has reduced IGFBP affinity, but it has a much shorter half-life than LR3. IGF-1 LR3's 13-aa N-terminal extension provides prolonged receptor engagement relative to both native IGF-1 and the DES form, making LR3 the preferred form for sustained-exposure research paradigms.
Is IGF-1 LR3 approved for human use?+
No. IGF-1 LR3 is not FDA-approved or approved by any regulatory agency for human use. As supplied by DMV Research, it is for in-vitro and pre-clinical laboratory research purposes only, not for human administration.
Research use only
All products are intended for laboratory and research use only (RUO) and are not for human consumption, ingestion, or any in-vivo use.
The statements on this page have not been evaluated by the FDA. IGF-1 LR3 is not intended to diagnose, treat, cure, or prevent any disease. Content is provided for laboratory research reference only.