Description
IGF-1 LR3
Long R3 IGF-1
A long-acting analog of insulin-like growth factor 1 — engineered with an arginine-3 substitution and a 13-residue N-terminal extension that sharply reduce its binding to IGF-binding proteins, extending half-life and potency while retaining full IGF-1 receptor activity.
Native IGF-1’s signal, re-engineered to last — and to stay free.
| IGF-1 LR3 (Long R3 IGF-1) is a recombinant 83-residue analog of insulin-like growth factor 1, developed at GroPep in Adelaide. It differs from the native 70-residue protein by two deliberate changes: an arginine substituted for glutamate at position 3, and a 13-amino-acid extension added to the N-terminus. Together these lower its affinity for the IGF-binding proteins that normally sequester circulating IGF-1.
At Guardian Labs, IGF-1 LR3 is supplied as a research-grade lyophilized powder, HPLC-verified above ninety-nine percent purity and lot-verified — supporting reproducible cell-proliferation, protein-synthesis, and growth-signaling data. |
The modifications sit at the IGF-binding-protein surface, not the receptor surface — so LR3 signals through IGF-1R exactly as native IGF-1 does, but stays free to do so far longer.
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Four features — same receptor, longer reach.
i
IGF-1R AgonismBinds the type-1 IGF receptor, a receptor tyrosine kinase, triggering autophosphorylation and recruitment of the IRS-1/2 and Shc adapter proteins. |
ii
PI3K & MAPKActivates the PI3K–Akt–mTOR cascade governing growth and protein synthesis, and the Ras–Raf–MEK–ERK cascade driving proliferation. |
iii
Reduced IGFBP BindingThe Arg-3 and N-terminal modifications cut affinity for IGFBP-1 through -6, raising the free, bioavailable fraction of the molecule. |
iv
Extended Half-LifeThe higher free fraction and improved metabolic stability yield a ~20–30 hour half-life and roughly three times the potency of native IGF-1. |
On the Engineering
The molecular distinction from native IGF-1 lies entirely at the binding-protein surface, not the receptor-binding surface. LR3 produces the same downstream signaling in receptor-expressing cells; what changed is how long it remains unbound and active. That clean separation of “what it does” from “how long it lasts” is why it has become a benchmark long-acting IGF-1 reagent in research.
Primary subjects of investigation — strictly laboratory use.
A.01
Cell ProliferationStudies of IGF-1R-driven cell growth, survival, and proliferation across cultured cell lines. |
A.02
Muscle Tissue ResearchResearch into skeletal-muscle hypertrophy and hyperplasia under sustained IGF-1 receptor signaling. |
A.03
Protein SynthesisInvestigating mTOR-mediated anabolism, amino-acid handling, and protein-synthesis dynamics. |
A.04
Cell CultureUse as a potent, long-acting growth-factor supplement for serum-free and bioprocess culture systems. |
Peer-reviewed literature supporting the research potential of this analog.
| i. |
Enhanced Potency of the LR3 AnalogThe foundational characterization by Francis and colleagues reporting that the Long R3 modification enhances biological potency relative to native IGF-1 in cell-culture systems, attributable to reduced binding-protein interference. |
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| ii. |
IGFBP Binding & BioavailabilityResearch characterizing how the Arg-3 and N-terminal modifications lower IGFBP affinity, raising the free fraction and extending functional half-life relative to native IGF-1. |
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| iii. |
IGF-1 Receptor SignalingStudies detailing IGF-1R activation of the PI3K–Akt–mTOR and Ras–Raf–MEK–ERK cascades that mediate growth, survival, and proliferation. |
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| iv. |
IGF-1 & Skeletal MuscleResearch into IGF-1-mediated skeletal-muscle hypertrophy and hyperplasia, examining satellite-cell activation and anabolic signaling in muscle models. |
Certificate of analysis available upon request.
| Chemical Name | IGF-1 LR3 · Long R3 IGF-1 |
| Composition | 83-residue recombinant IGF-1 analog (E3R + 13-aa N-terminal extension) |
| Molecular Formula | C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉ |
| Molecular Weight | 9117.60 g/mol |
| CAS Number | 946870-92-4 |
| Receptor Target | Type-1 IGF Receptor (IGF-1R) |
| Format | Lyophilized Powder (Freeze-dried) |
| Vial Size | 1 mg |
| Purity | > 99% (HPLC Verified) |
| Storage | Store at −20°C · Protect from light |
| Reconstitution | Bacteriostatic Water |
