Research Overview
IGF-1 LR3, more formally Long Arginine 3 Insulin-like Growth Factor I, is a synthetic 83-amino-acid analogue of native human IGF-1. The molecule is modified in two important ways. First, an N-terminal extension of 13 amino acids is added to the native IGF-1 sequence. Second, the arginine residue at position 3 of the IGF-1 sequence is substituted for the native glutamic acid. These modifications give the molecule a molecular weight of 9115.9 g/mol and substantially extend its half-life in comparison with native IGF-1.
The longer half-life is one of the principal reasons IGF-1 LR3 is widely used in cell culture and animal model research; it reduces the frequency of dosing required to maintain a measurable signalling response. The compound is studied in muscle research, growth-factor pathway research, hepatic and IGF-axis biology, and tissue repair models. It binds the IGF-1 receptor but has substantially reduced affinity for IGF-binding proteins, which is what gives it the extended bioavailability profile that researchers find useful.
Each vial supplied by Origin Research contains 1mg of lyophilised IGF-1 LR3 at 99.65% purity by HPLC, sealed under inert atmosphere with a batch-specific Certificate of Analysis available on request. Strictly for in-vitro and preclinical research.
Mechanism Studied in Research
IGF-1 LR3 acts on the same receptor as native IGF-1 but displays markedly different pharmacokinetics in research models. The reduced affinity for IGF-binding proteins results in a larger freely available fraction of the compound, allowing more sustained receptor activation in experimental systems.
Binding of IGF-1 LR3 activates the IGF-1 receptor tyrosine kinase and initiates downstream intracellular signalling pathways, most notably the PI3K-Akt-mTOR pathway and the Ras-Raf-MEK-ERK cascade. These pathways regulate cellular proliferation, protein synthesis, differentiation and survival signalling, making IGF-1 LR3 a frequently investigated tool in growth-factor research.
Published studies have examined IGF-1 LR3 in muscle-cell differentiation, satellite-cell activation, tissue-regeneration models and metabolic signalling experiments. Investigators have also explored downstream interactions involving glucose transport, amino-acid utilisation, anabolic signalling networks and IGF-binding protein interactions.
Because the molecule remains active for longer periods than native IGF-1, researchers often use it when sustained receptor occupancy is required. The extended duration of signalling has made IGF-1 LR3 a common reference compound in experimental growth-factor and receptor-signalling research.
Research Applications
Muscle and myoblast research. IGF-1 LR3 is one of the most commonly studied growth-factor analogues in skeletal-muscle investigations. Research protocols frequently evaluate myoblast differentiation, protein synthesis, satellite-cell activation and downstream mTOR signalling.
Growth-factor pathway research. Because IGF-1 LR3 exhibits prolonged receptor activity, it is widely used to investigate IGF-1 receptor signalling, PI3K-Akt pathway activation and cellular growth responses. Researchers commonly compare signalling duration between native IGF-1 and IGF-1 LR3.
Hepatic and metabolic research. Experimental studies have investigated IGF-1 LR3 in glucose-regulation models, insulin-signalling research and growth-factor feedback mechanisms. The reduced binding to IGF-binding proteins allows researchers to study receptor-mediated effects with less interference from carrier proteins.
Tissue repair and proliferation research. IGF-1 LR3 has been evaluated in laboratory models examining cellular proliferation, migration, extracellular-matrix activity and regenerative signalling pathways. The extended half-life provides a useful tool for experiments requiring sustained receptor activation over multiple hours.
Reconstitution Reference
IGF-1 LR3 is supplied as a 1mg lyophilised powder under inert atmosphere. A commonly used laboratory preparation uses bacteriostatic water as the reconstitution diluent.
A practical working example is the addition of 1mL bacteriostatic water to the vial to produce a concentration of 1000mcg/mL. Alternative dilution schemes may be used depending on the intended research protocol and target concentration.
The diluent should be introduced slowly down the inner wall of the vial without directing the stream onto the peptide cake. Gentle swirling is preferred. Vigorous shaking should be avoided to minimise foam formation and mechanical stress.
Reconstitution details, final concentration and preparation dates should be documented within laboratory records. Intended strictly for in-vitro and preclinical research use only.
Storage and Handling
Store lyophilised IGF-1 LR3 at -20°C protected from light and moisture. Under these conditions, unopened material remains stable for long-term laboratory storage.
Following reconstitution, working solutions are commonly stored at 2-8°C and used within established research timelines. Repeated freeze-thaw cycles should be avoided because they may reduce peptide integrity and signalling consistency.
Researchers should prepare single-use aliquots when practical and maintain appropriate chain-of-custody documentation. Allow refrigerated material to reach room temperature before opening to minimise condensation inside the vial.
Any solution showing visible precipitation, discolouration or contamination should be discarded. Intended for laboratory research use only.
References
[2] Francis G.L. et al. (1992). Long-R3-IGF-I and IGF-binding proteins in disease states. Growth Hormone & IGF Research.
[3] Adams G.R. (2002). Invited Review: Autocrine/paracrine IGF-I and skeletal muscle adaptation. Journal of Applied Physiology. PMID 11960993
[4] Clemmons D.R. (2009). Modifying IGF activity: an approach to treat endocrine disorders, atherosclerosis and cancer. Nature Reviews Drug Discovery. PMID 19721444
[5] Bach M.A. et al. (2000). Insulin-like growth factor I receptor and insulin receptor mechanisms of signalling and clinical implications. Hormone Research.