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. |
Four features — same receptor, longer reach.
iIGF-1R AgonismBinds the type-1 IGF receptor, a receptor tyrosine kinase, triggering autophosphorylation and recruitment of the IRS-1/2 and Shc adapter proteins. | iiPI3K & MAPKActivates the PI3K–Akt–mTOR cascade governing growth and protein synthesis, and the Ras–Raf–MEK–ERK cascade driving proliferation. | iiiReduced IGFBP BindingThe Arg-3 and N-terminal modifications cut affinity for IGFBP-1 through -6, raising the free, bioavailable fraction of the molecule. | ivExtended 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.01Cell ProliferationStudies of IGF-1R-driven cell growth, survival, and proliferation across cultured cell lines. | A.02Muscle GrowthResearch into skeletal-muscle hypertrophy and hyperplasia under sustained IGF-1 receptor signaling. | A.03Protein SynthesisInvestigating mTOR-mediated anabolism, amino-acid handling, and protein-synthesis dynamics. | A.04Cell 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. | View on PubMed → |
| 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. | View on PubMed → |
| 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. | View on PubMed → |
| iv. | IGF-1 & Skeletal MuscleResearch into IGF-1-mediated skeletal-muscle hypertrophy and hyperplasia, examining satellite-cell activation and anabolic signaling in muscle models. | View on PubMed → |
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 |
All products listed are intended exclusively for laboratory research and development purposes. They are not intended for human consumption, diagnostic, or therapeutic use. Customers must be at least 21 years of age to purchase.
