IGF-1 LR3 is a growth peptides research compound currently in stock directly from a verified Chinese manufacturer. Every batch is HPLC-verified and shipped with a Certificate of Analysis (COA). Sourcing is direct — no intermediaries. Minimum order value is $600 USD. International shipping available.
IGF-1 LR3 (Long Arg3 Insulin-like Growth Factor-I) is a recombinant 83-amino acid analogue of human IGF-1, extended by a 13-residue N-terminal sequence and containing a glutamate-to-arginine substitution at position 3 (Glu³→Arg³). This two-part structural modification produces a dramatic reduction in IGF-binding protein (IGFBP) affinity — approximately 2–3 orders of magnitude lower than native IGF-1 — while retaining full IGF-1 receptor (IGF-1R) binding and activation. Since IGFBPs sequester the majority of circulating IGF-1 in vivo (only ~1% is free at any time), the reduced IGFBP affinity of LR3 translates to a substantially greater proportion of free, bioactive peptide per administered dose. This property makes IGF-1 LR3 the standard IGF-1 variant used in most cell biology and animal pharmacology research where systemic IGF-1 activity is the research endpoint.
The extended half-life of IGF-1 LR3 in vivo — approximately 20–30 hours compared to 12–15 minutes for native IGF-1 — results directly from the reduced IGFBP buffering. This makes it a valuable tool in studies examining the chronic anabolic and mitogenic effects of IGF-1R activation across tissues including skeletal muscle, bone, liver, and the central nervous system. IGF-1 LR3 is widely used in cell culture research as a growth factor supplement and in defined-serum conditions where endogenous growth factor concentrations must be controlled — particularly in hybridoma, CHO, and stem cell culture protocols where it partially replaces serum-derived IGF-1.
PeptidesFromChina.co supplies IGF-1 LR3 as lyophilized powder at ≥98% purity, verified by HPLC and confirmed by mass spectrometry. Certificates of Analysis available per batch. Wholesale quantities available on request. This compound is for laboratory research use only.
| Chemical Class | Long-acting IGF-1 Analogue / Recombinant Peptide |
|---|---|
| Full Name | Long Arg3 Insulin-like Growth Factor-I |
| CAS Number | 946870-92-4 |
| Molecular Weight | ~9117.5 Da |
| Sequence Length | 83 amino acids (native IGF-1: 70 AA + 13 AA N-terminal extension) |
| Key Modification | Glu³→Arg³ substitution; 13 AA N-terminal extension |
| Receptor Target | IGF-1R (IGF-1 receptor); minimal IR cross-reactivity |
| IGFBP Affinity | ~1000× lower than native IGF-1 |
| Half-life (research) | ~20–30 h (vs. ~12 min for native IGF-1) |
| Storage | -20°C lyophilized; 4°C reconstituted (up to 28 days) |
| Molecular Formula | N/A — 83-aa protein analogue; see COA |
| Name | Strength | Pack Size | Purity | Availability | Price (USD) |
|---|---|---|---|---|---|
| IGF-1 LR3 | 0.1 mg | 10 vials | ≥98% | In Stock | $38.00 |
| IGF-1 LR3 | 1 mg | 10 vials | ≥98% | In Stock | $225.00 |
Testing method: HPLC / LC-MS (["HPLC","LC-MS","Endotoxins","Water Content"]). Every batch is tested before shipment. Purity ≥99% confirmed per batch.
Certificate of Analysis: Simple COA. Documentation is available for every batch sold.
IGF-1 LR3 is the standard tool compound for sustained IGF-1R activation in cell-based studies. Downstream signalling endpoints — PI3K/Akt/mTOR, MAPK/ERK — are characterised using phosphoproteomics, Western blotting, and proximity ligation assays. The compound's IGFBP-resistance removes the confound of IGFBP-3 and IGFBP-5 competitive inhibition present in serum-containing culture conditions, making dose-response relationships more reproducible than with native IGF-1. IGF-1R knockout cell lines and blocking antibodies (αIR3) are used alongside IGF-1 LR3 to confirm receptor specificity.
IGF-1 and IGF-1R signalling are central to skeletal muscle hypertrophy, satellite cell activation, and atrophy resistance. C2C12 myoblast differentiation assays (myotube fusion index, myosin heavy chain expression) and primary mouse satellite cell cultures are standard formats for characterising IGF-1 LR3's myogenic effects. In vivo, rodent hindlimb unloading models (muscle atrophy from immobilisation) use IGF-1 LR3 to test whether IGF-1R activation preserves muscle mass and force output — mechanistically relevant to research on sarcopenia and disuse atrophy.
IGF-1 LR3 is widely used as a recombinant serum substitute in cell culture media formulations. CHO, BHK, HEK293, and hybridoma cell lines supplemented with IGF-1 LR3 in defined or low-serum media show improved viability, proliferation, and biologic production yields. The LR3 form is preferred over native IGF-1 because its IGFBP resistance results in more consistent bioavailability in conditioned media — native IGF-1 is partially sequestered by secreted IGFBPs in conditioned medium, causing variable effective concentrations between experiments.
IGF-1 signalling is required for longitudinal bone growth and periosteal apposition during development, and for maintenance of bone mineral density in adults. In vitro models using primary osteoblasts, osteoblast-like cell lines (MC3T3-E1, Saos-2), and ex vivo fetal long bone cultures characterise IGF-1 LR3's effects on osteoblast proliferation, alkaline phosphatase activity, and mineralisation kinetics. Chondrocyte models (ATDC5, primary articular chondrocytes) use IGF-1 LR3 in studies of cartilage matrix synthesis and the IGF-1/IGFBP axis in osteoarthritis.
Native IGF-1 has very high binding affinity for circulating and locally produced IGF-binding proteins (IGFBPs), which sequester it and limit receptor availability. This makes dose-response relationships in serum-containing assays highly variable because IGFBP concentrations differ between batches of serum and between cell lines. IGF-1 LR3's ~1000-fold reduced IGFBP affinity means most of the added peptide remains free and receptor-accessible, producing more reproducible and interpretable dose-response data. Its 20–30 hour in vivo half-life also reduces dosing frequency in animal studies.
For proliferation assays, typical research concentrations range from 1–100 ng/mL (approximately 0.1–11 nM given MW of ~9.1 kDa). For defined serum-free media as a serum substitute, concentrations of 10–100 ng/mL are commonly used in CHO and hybridoma culture protocols. These concentrations are substantially lower than those used for native IGF-1 to achieve equivalent effects, because of the LR3 variant's reduced IGFBP competition in conditioned media.
Reconstitute in sterile 10 mM acetic acid (0.1% acetic acid in sterile water) or PBS containing 0.1–0.5% BSA as a carrier protein to prevent adsorption to plastic surfaces. Avoid plain water at neutral pH without carrier protein — IGF-1 peptides can adsorb to tube walls at low concentrations. Working aliquots at 1–100 μg/mL in 0.1% BSA/PBS are stable for up to 28 days at 4°C. Stock solutions at higher concentrations can be stored at -80°C for long-term use.
Yes. IGF-1 LR3 is available through PeptidesFromChina.co on a B2B wholesale basis. Pricing, vial sizes, and volume tiers are provided upon request after account verification. Contact us via the Request page or Contact form.
For laboratory research use only. Not for human or veterinary use. PeptidesFromChina.co is a B2B wholesale supplier operating under strict research-use-only terms. All products are sold exclusively for in vitro and preclinical research purposes.