IGF-1 LR3 (Long R3) is a modified 83-amino-acid analog of Insulin-like Growth Factor 1 with reduced IGFBP binding and an extended half-life of approximately 20 to 30 hours. It is the preferred IGF-1 variant for most research applications.

How should I store IGF-1 LR3?

Store lyophilized IGF-1 LR3 at -20°C for long-term storage or 2-8°C for short-term use. After reconstitution with bacteriostatic water, keep refrigerated at 2-8°C and use within 14 days. Avoid repeated freeze-thaw cycles.

What purity is your IGF-1 LR3?

Our IGF-1 LR3 is independently tested by Janoshik Analytical at a minimum of 98% HPLC purity. Certificate of analysis is accessible on the product page for every batch.

Why IGF-1 LR3 instead of native IGF-1?

Native IGF-1 has a very short half-life (~20 minutes) due to rapid binding by IGF-binding proteins. The LR3 modifications reduce this binding, providing 2 to 3 times higher bioactivity and a much longer half-life, making the peptide far more practical for research.

Buy IGF-1 LR3 Peptide ≥98% Purity

Name: IGF-1 LR3
Brand: PeptidesDirect
SKU: PD-IGF1LR3-1MG
Price: 59.99 EUR
Availability: InStock

Modified IGF-1 analog

A synthetic version of IGF-1 with an arginine swap at position 3 and a 13 amino acid extension on the N-terminus, giving 83 amino acids in total versus 70 in the natural protein.

Reduced IGFBP binding

The structural changes lower its affinity for IGF binding proteins, the carriers that normally hold IGF-1 inactive in plasma. More of the molecule stays free and available to its receptor.

Extended circulating life

Because it slips past the binding-protein system, LR3 keeps its biological activity for far longer than native IGF-1 in research models, a property exploited in cell culture and animal studies.

mTOR and Akt pathway activation

Once bound to the IGF-1 receptor, the molecule fires the same PI3K, Akt, and mTOR cascades that drive protein synthesis and cell growth in muscle and other tissues.

Satellite cell signaling

Studied as a trigger for muscle satellite cells, the resident stem cells that fuse into existing fibres during repair and growth in skeletal muscle research.

Standard cell culture reagent

Long-R3 IGF-1 is widely used as a serum substitute in mammalian cell culture, where it supports proliferation of CHO, HEK, and primary cell lines at much lower concentrations than native IGF-1.

Research areas

Muscle anabolismCell proliferationRecovery and repairmTOR signalingCell culture

What is IGF-1 LR3

IGF-1 LR3 is a laboratory-engineered version of insulin-like growth factor 1, the hormone that mediates most of the growth-promoting effects of growth hormone in the body. The natural protein is 70 amino acids long. LR3 carries two changes: an arginine in place of the glutamic acid at position 3, and a 13 amino acid extension added to the front of the chain. The result is an 83 amino acid analog with the same receptor-binding region as native IGF-1 but a very different behaviour in plasma.

We supply it in lyophilized (freeze-dried) form for research and cell culture use.

How it works

IGF-1 in the body is almost never free. More than 99 percent of it travels bound to a family of carrier proteins called IGFBPs, which control how much active hormone reaches tissues and when. The arginine substitution at position 3 cripples that interaction. With the binding proteins out of the way, LR3 reaches the IGF-1 receptor more easily and stays in circulation longer.

At the receptor, LR3 triggers the same signaling cascades as native IGF-1: PI3K and Akt activation, then mTOR, the master regulator of protein synthesis. In skeletal muscle research, this axis drives ribosome activity, fibre hypertrophy, and the activation of satellite cells that fuse into damaged fibres during repair. Studies in cardiomyocytes show the same PI3K and ERK pathways supporting cell proliferation. Because the molecule resists binding-protein sequestration, very low concentrations are enough to produce strong responses in cell culture, which is why it has become a standard reagent in mammalian cell production.

Often studied alongside

LR3 sits at the bottom of the growth hormone axis. Researchers exploring the full pathway often combine it with peptides that act further upstream: GHRH analogs that prompt the pituitary to release growth hormone, or ghrelin-mimetic GHRH-secretagogue combinations that amplify the pulse.

GHRH analog used to stimulate endogenous growth hormone

Sermorelingrowth

GHRH(1-29) analog for physiological growth hormone stimulation research

Selective ghrelin-receptor agonist for GH-pulse research

Ipamorelingrowth

Highly selective growth hormone releaser that triggers natural GH pulses without raising cortisol or prolactin. Clean GH stimulation with minimal side effects - the most targeted growth hormone peptide available.

GHRH plus secretagogue combination, the most studied growth-axis stack

CJC-1295/Ipamorelin (No-DAC)growth

2-in-1 growth hormone blend: CJC-1295 no-DAC (Modified GRF 1-29, 5 mg) + Ipamorelin (5 mg) combined in one vial. The CJC-1295 component is the short-acting no-DAC variant (about 30 minute half-life), not the long-acting DAC form. Stimulates natural GH release through two different pathways for amplified, more physiological growth hormone pulses.

Recombinant human growth hormone, the upstream signal for IGF-1 production

For reconstitution, the standard solvent in published protocols is bacteriostatic or sterile water.

Standard solvent for reconstitution

Bacteriostatic Wateraccessories

USP-grade sterile water with 0.9% benzyl alcohol - the standard solvent for reconstituting lyophilized peptides. Essential accessory for any peptide research. Each vial is sealed and ready to use.

Documentation

Material specification

Purity

≥98% (HPLC verified)

Test method

HPLC + mass spectrometry

Form

Lyophilized powder

Storage (sealed)

2 to 8 °C, light-protected

Storage (reconstituted)

2 to 8 °C, use within 4 weeks

CoA

Batch-specific, third-party (Janoshik)

Selected research

Research use only

This material is sold strictly for in-vitro research and laboratory use. Not intended for human or animal consumption, medical, cosmetic, or household applications. Suitable only for professional laboratory environments.