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What Is IGF-1 LR3? A Research Overview

Explicit Research  ·  Research Compound Overview
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Research Use Only. IGF-1 LR3 is sold by Explicit Research exclusively for laboratory and research purposes. This article summarizes published preclinical and experimental literature. It is not medical advice and does not constitute a recommendation for human use. All compounds are for in vitro and animal research only.

All information below describes the compound's chemical identity, laboratory handling, and the published research literature. It describes molecular targets and results in laboratory and animal models only — not effects in humans — and is not evidence of any human benefit.

What Is IGF-1 LR3?

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is an 83-amino-acid recombinant analogue of insulin-like growth factor 1. It is engineered with an N-terminal 13-residue extension and a glutamate-to-arginine substitution at position 3, structural modifications that distinguish it from the native peptide. It does not occur freely in nature; it is a laboratory-produced analogue commonly used as a reference compound in preclinical investigation.

It is supplied as a reference compound for in vitro and animal research use only. The sections below summarize its chemical identity, laboratory handling, the molecular targets and model systems examined in the published literature, and the primary references — without describing outcomes, efficacy, or effects in humans.

Research Targets & Pathways

Published preclinical literature has examined IGF-1 LR3 in relation to several molecular systems. These are pathway associations reported in laboratory and animal models; refer to the cited studies for methods and findings.

Model Systems Studied

IGF-1 LR3 and related IGF-1 isoforms have been used as test compounds across a range of published preclinical model systems, primarily in rodents and in vitro cell assays. Refer to the cited literature for study designs, endpoints, and findings.

Molecular & Technical Profile

83-amino-acid recombinant protein  |  MW 9117.5 g/mol  |  CAS 946870-92-4  |  Full residue sequence not specified by supplier

Storage, Reconstitution & Working Concentrations

Lyophilized storage−20°C, protected from light and moisture; reported stable up to ~24 months as lyophilized powder
Reconstituted storage2–8°C up to ~28 days; avoid repeated freeze–thaw — aliquot into single-use volumes where possible
SolubilityFreely soluble in sterile water or aqueous buffers (e.g. PBS, pH 7.4); may be dissolved in a minimal volume of acetic acid (0.1–1%) then diluted into aqueous buffer — DMSO not recommended as primary solvent
ReconstitutionEquilibrate vial to room temperature (15–20 min) before opening; add diluent slowly to the vial wall — not directly onto the cake; swirl gently — do not vortex; allow to stand 1–2 min to clarify
Stock solutionTypically 0.1–1.0 mg/mL in sterile water or 0.1% acetic acid; further dilute into PBS or culture medium to working concentration
In vitro working range1–100 ng/mL (approx. 0.08–8 nM) in cell-based assays (e.g. MCF-7, C2C12 myoblast, IGF-1R phosphorylation, glucose-uptake); titrate per cell line and endpoint
Animal model dosingSee cited literature for model-specific concentration ranges and administration protocols
Endotoxin<1 EU/mg (LAL assay); confirm lot-specific COA before use in sensitive cell systems

Storage, reconstitution, and working-concentration values are general laboratory guidance for in vitro and animal research; always confirm against the lot-specific Certificate of Analysis.

Current Research Status

As of the time of this writing, IGF-1 LR3 has not been approved by the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA), or any regulatory body for human or animal use. The available evidence base is primarily preclinical, derived from rodent and in vitro models. The research-grade material supplied by Explicit Research is a reference compound for laboratory research use only and is not an approved drug product. Ongoing research continues to characterize the compound's mechanistic profile and identify which experimental findings may have translational relevance.

Research FAQ

Is IGF-1 LR3 approved for human use?

No. IGF-1 LR3 has not been approved by the FDA, EMA, or any regulatory body for human or animal use. The evidence base is preclinical (rodent and in vitro models), and the compound is supplied for laboratory research use only — not for human consumption.

What is IGF-1 LR3's molecular profile and sequence?

An 83-amino-acid recombinant analogue of insulin-like growth factor 1, carrying an N-terminal 13-residue extension and a glutamate-to-arginine substitution at position 3 — MW 9117.5 g/mol, CAS 946870-92-4. The full residue sequence is not specified by the supplier.

How is IGF-1 LR3 stored and reconstituted?

Store lyophilized at −20°C, protected from light and moisture. Reconstitute in sterile water or aqueous buffer (optionally a minimal volume of 0.1–1% acetic acid diluted into buffer); store the reconstituted solution at 2–8°C for up to ~28 days and avoid repeated freeze–thaw.

What targets and model systems has IGF-1 LR3 been studied in?

Preclinical work has characterized IGF-1 LR3 in relation to IGF-1 receptor signaling, the PI3K/Akt/mTOR axis, IRS-1/MAP-kinase cascades, IGF-binding-protein interaction, and myogenic transcription factors, across skeletal-muscle, neural, cardiac, gastrointestinal, and in vitro cell-assay model systems.

Selected References

  1. Baxter et al. — Characterization of binding of IGF-1 LR3 to IGF-binding proteins; measured reduced IGFBP affinity versus native IGF-1 in serum binding assays. J Biol Chem, 1992.
  2. Francis et al. — Pharmacokinetic profiling of long R3 IGF-1 versus native IGF-1; measured plasma half-life and receptor occupancy in rat models. J Mol Endocrinol, 1993.
  3. Tomas et al. — Compared anabolic potency of IGF-1 LR3 and native IGF-1 in rat skeletal muscle; measured nitrogen retention and protein synthesis rates. J Endocrinol, 1993.
  4. Skottner et al. — Receptor binding affinity and in vivo growth-promoting activity of IGF-1 analogues; measured IGF-1R activation in hypophysectomized rat model. Growth Regul, 1993.
  5. Musaro et al. — Measured IGF-1 isoform-driven PI3K/Akt pathway activation in skeletal muscle hypertrophy; assessed myofiber cross-sectional area in transgenic mouse model. J Cell Biol, 1999.
  6. Semsarian et al. — Assessed calcineurin-independent IGF-1-mediated skeletal muscle growth; measured fiber type composition and hypertrophic gene expression in vitro and in vivo. J Biol Chem, 2001.
  7. Rommel et al. — Quantified IGF-1/PI3K/Akt/mTOR axis activation in myotube hypertrophy; measured S6K1 phosphorylation and protein synthesis in cultured muscle cells. Nat Cell Biol, 2001.
  8. Dupont et al. — Measured IGF-1 receptor downstream signaling through IRS-1 and MAP kinase cascades in muscle cell proliferation and differentiation assays. J Biol Chem, 2005.
  9. Chakravarthy et al. — Measured satellite cell proliferation and differentiation in response to IGF-1 isoforms; assessed MyoD and myogenin expression in injured rodent muscle. J Physiol, 2001.
  10. Philippou et al. — Quantified local IGF-1 splice variant effects on satellite cell activation; measured Pax7 and myf5 expression in rodent muscle repair model. Mol Med, 2007.
  11. Matheny et al. — Compared regenerative potency of IGF-1 isoforms in dystrophic muscle; measured fiber regeneration rate, satellite cell number, and functional recovery in mdx mice. Growth Horm IGF Res, 2010.
  12. Carro et al. — Intranasal long R3 IGF-1 treatment assessed amyloid plaque remodeling in cerebral cortex; measured plaque burden and cognitive performance in 5XFAD mouse model. J Alzheimers Dis, 2025.
  13. Carro et al. — Measured IGF-1 transport across the blood-brain barrier and downstream neuroprotective signaling; assessed amyloid beta clearance and tau phosphorylation in rodent model. Nat Med, 2003.
  14. Conti et al. — Measured IGF-1-mediated cardioprotection after experimental myocardial infarction; assessed infarct size, cardiomyocyte apoptosis, and Akt activation in rat model. J Clin Invest, 1999.
  15. Liu et al. — Measured IGF-1 preservation of gastric pacemaker interstitial cells of Cajal in aging; assessed ERK1/2 phosphorylation and gastric motor function in aged rodent model. Cell Mol Gastroenterol Hepatol, 2023.
  16. LeRoith et al. — Reviewed IGF-1 axis involvement in cancer risk and tumor proliferation; measured IGF-1R-driven cell cycle progression and anti-apoptotic signaling across cancer cell lines. Nat Rev Cancer, 2004.
  17. Pollak et al. — Assessed epidemiological and mechanistic links between elevated IGF-1 signaling and cancer incidence; reviewed circulating IGF-1 levels in prospective human cohort studies. Nat Rev Cancer, 2008.