IGF-1LR3

Description

What is IGF-1 LR3?

IGF‑1 LR3 (Long [Arg³] IGF‑1) is an 83‑amino‑acid recombinant analog of human IGF‑1. It carries two structural modifications: (1) Glu³ is replaced with Arg³, which dramatically reduces binding to IGF‑binding proteins (IGFBP‑1 through ‑6); and (2) a 13‑residue N‑terminal presequence extends the molecule. The net effect in research preparations is a longer plasma half‑life (~20‑30 h vs. ~10 min for native IGF‑1 in solution) and greater bioavailability to the IGF‑1 receptor.

Mechanism of Action

• Agonist at the IGF‑1 receptor (IGF1R) tyrosine kinase
• Activates PI3K/AKT and Ras/MAPK pathways driving protein synthesis, cell proliferation, and anti‑apoptotic signaling
• Cross‑reactivity at the insulin receptor at higher concentrations
• Reduced IGFBP binding due to Arg³ substitution increases free IGF‑1 bioavailability

Compound Properties

• Molecular formula: C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉
• Molecular weight: ~9111 Da
• Sequence: 13‑aa N‑terminal extension + Arg³‑substituted mature IGF‑1 (83 residues total)
• Form: Lyophilized powder
• Source: Recombinant expression (E. coli); ≥98% purity by HPLC/MS

Research‑Reference Dosing

IGF‑1 LR3 is primarily used as a cell‑culture and animal‑research reagent:

• Francis et al., Journal of Molecular Endocrinology (1992, foundational): characterization of Long [Arg³] IGF‑1 in cell culture.
• Standard cell‑culture use: 10–100 ng/mL for proliferation/differentiation assays.
• In‑vivo rodent studies: micro‑osmotic pump or subcutaneous dosing for tissue‑growth research.
• No FDA‑approved human indication for IGF‑1 LR3 exists.

Research Findings

• Widely used to study IGF‑1 pathway signaling independent of IGFBP sequestration
• Reliable proliferation/differentiation of myoblasts, chondrocytes, and neural stem cells in culture
• Promotes muscle and organ growth in preclinical rodent studies

Known Side Effects Reported in Research/Trials

• Hypoglycemia (cross‑reactivity with insulin receptor at elevated doses)
• Injection‑site reactions
• Theoretical oncogenic concern from sustained IGF‑1 pathway activation; epidemiology links elevated IGF‑1 to colorectal, breast, and prostate cancer risk
• Arthralgia, headache, transient edema reported with native IGF‑1 in clinical settings
• No human safety profile for IGF‑1 LR3 specifically

Storage & Handling

• Lyophilized (unreconstituted) vials: store at −20°C long‑term; short‑term 2–8°C acceptable.
• After reconstitution with bacteriostatic or sterile water: store at 2–8°C; use within 14–28 days per standard peptide stability guidance.
• Protect from light, heat, and repeated freeze‑thaw cycles. Handle in a sterile laboratory environment.

Certificate of Analysis

A Certificate of Analysis (COA) confirming identity and purity by HPLC / MS is available upon request. Contact Lonestar Peptides for lot‑specific documentation.

Summaries reference peer‑reviewed preclinical and clinical literature available as of early 2025. Newer findings may not be reflected. Researchers should consult current literature and conduct their own due diligence. Lonestar Peptides makes no claim of therapeutic benefit.