IGF-1 LR3: Growth Factor Research Overview
IGF-1 LR3 is a long-acting analogue of insulin-like growth factor-1 widely used in cell biology and metabolic research. Here is what Canadian researchers need to know.
- IGF-1 LR3 is a long-acting synthetic analogue of human IGF-1; an arginine substitution at position 3 plus an N-terminal extension cut IGF-binding-protein affinity roughly 1000-fold, greatly extending its half-life.
- It activates the IGF-1 receptor (IGF1R), driving PI3K/Akt, MAPK/ERK, and mTOR signalling studied in cell survival, proliferation, and anabolic research.
- Common research uses include a cell-culture growth-factor supplement (satellite cells, myoblasts) and muscle-physiology, metabolic, and cancer-biology models.
- Its prolonged activity suits sustained receptor activation in vivo, but researchers should account for that extended action when designing protocols.
- Popular Peptides supplies IGF-1 LR3 (1 mg) with independent purity verification and a COA; research use only.
What Is IGF-1 LR3?
IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3) is a modified synthetic analogue of human IGF-1. The "Long R3" designation refers to structural modifications that significantly extend its half-life compared to native IGF-1.
Native IGF-1 has a short circulating half-life due to its high affinity for IGF binding proteins (IGFBPs), which sequester it in the bloodstream. IGF-1 LR3 features an arginine substitution at position 3 and an N-terminal glutamic acid extension that reduces IGFBP binding by approximately 1000-fold, resulting in substantially prolonged biological activity.
Mechanism of Action
IGF-1 LR3 activates the IGF-1 receptor (IGF1R), a receptor tyrosine kinase that initiates several downstream signalling cascades:
**PI3K/Akt pathway**: Associated with cellular survival, glucose uptake, and protein synthesis. Activation of this pathway has been extensively studied in the context of muscle cell biology and metabolic regulation.
**MAPK/ERK pathway**: Involved in cell proliferation, differentiation, and gene expression. IGF-1 receptor signalling through MAPK has been studied in developmental biology and cancer research.
**mTOR activation**: The mammalian target of rapamycin integrates growth factor signals with nutrient sensing. IGF-1R/Akt-mediated mTOR activation is a key node in anabolic signalling research.
Research Applications
IGF-1 LR3 is widely used across several research disciplines:
**Cell biology**: As a growth factor supplement in cell culture media, particularly for satellite cells, myoblasts, and other cell types that express high levels of IGF1R
**Muscle physiology research**: Studies examining protein synthesis, muscle fibre hypertrophy, and satellite cell activation in animal models
**Metabolic research**: Investigation of glucose uptake, insulin sensitisation, and the intersection of the IGF-1 and insulin signalling pathways
**Cancer biology**: Given IGF1R's role in tumour cell survival and proliferation, IGF-1 LR3 is used as a reference agonist in oncology research
Considerations for Researchers
The extended half-life of IGF-1 LR3 compared to native IGF-1 makes it particularly useful for in vivo research where sustained receptor activation is required. However, researchers should account for its prolonged activity when designing experimental protocols.
Popular Peptides supplies IGF-1 LR3 (1mg) as a research-grade compound with independent purity verification and Certificate of Analysis.
Important Notice
For research use only. Not intended for human or veterinary therapeutic application.
What to order
Compounds referenced in this guide:
- —**IGF-1 LR3**
Popular Peptides ships from Vancouver, BC — typically 2 to 5 business days, tracked and insured, with no customs clearance and no border seizure risk. Every batch is third-party tested (HPLC for purity, LC-MS for identity) and its certificate of analysis is retrievable by lot number. Priced in Canadian dollars, free shipping over $300 CAD.
Browse every published lab result before you order, or check the reference library for molecular data on each compound.
Frequently asked questions
What does LR3 mean?
Long R3 — an arginine substitution at position 3 plus a 13-residue N-terminal extension. Both modifications reduce affinity for IGF binding proteins.
How is IGF-1 LR3 different from native IGF-1?
LR3 evades IGF binding proteins, which substantially extends its functional half-life. Native IGF-1 is extensively bound by IGFBPs. See our full comparison.
Which should I use?
If the research question involves binding-protein interaction or the native signalling axis, use native IGF-1 — LR3 was built specifically to bypass that mechanism.
Every batch we sell is independently third-party tested, with the full Certificate of Analysis published and checkable by lot number.