Description
IGF-1 LR3 Peptide Overview
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a recombinant 83-amino-acid analogue of human IGF-1. It differs from the native hormone in two ways: an arginine substituted for glutamic acid at position 3, and a 13-residue extension peptide added to the N-terminus. Both modifications were engineered to change how the molecule behaves in culture, and it is produced by recombinant expression in E. coli.
Reduced Binding-Protein Affinity
Native IGF-1 is largely sequestered by the six IGF binding proteins, which limits how much free peptide is available in an experimental system. The LR3 modifications sharply reduce that binding, so more of the analogue remains unbound. In research models this translates to roughly threefold greater potency than native IGF-1 at equivalent concentrations, and a longer functional half-life in culture media.
IGF-1 Receptor Signalling
The analogue signals through the type I IGF receptor, a tyrosine kinase that activates the PI3K/Akt and MAPK/ERK cascades. These are the canonical pathways studied for cellular proliferation, differentiation and protein synthesis, which makes IGF-1 LR3 a common tool compound in growth-factor and receptor-binding work.
Myoblast and Skeletal-Muscle Models
Much of the published research uses skeletal muscle systems. In vitro studies examine myoblast proliferation and fusion in culture, and preclinical rodent work has investigated sustained-release formulations in volumetric muscle loss models.
Handling and Stability
As a recombinant protein rather than a short synthetic peptide, IGF-1 LR3 is sensitive to repeated freeze-thaw cycles and to adsorption onto plastic surfaces. Research protocols commonly aliquot reconstituted material and use a carrier protein where the assay permits.
Specifications
- CAS Number: 946870-92-4
- Molecular Formula: C400H625N111O115S7 (approximate)
- Class: Recombinant IGF-1 analogue (83 amino acids)
- Molar Mass: Approximately 9.1 kDa
- Expression System: E. coli
- Endotoxin: Less than 1 EU per microgram
- Storage: Store lyophilized at -20C. Refrigerate after reconstitution.
- Form: Lyophilized powder in a sterile glass vial.
- Purity: Minimum 98%
- Quantity: 1mg per vial
- Color: White
Important Note: This product is intended solely for in vitro laboratory research by licensed professionals. It is not approved by the FDA for human or animal use and should not be misbranded, misused, or mislabeled as a drug, food, supplement, or cosmetic.
References:
- Tomas F.M. et al. – Long-R3-IGF-I and growth of the rat – Journal of Endocrinology
- Francis G.L. et al. – Insulin-like growth factor analogues with reduced binding-protein affinity – Biochemical Journal
- Philippou A. et al. – The role of IGF-1 in skeletal muscle physiology – In Vivo
- Laron Z. – Insulin-like growth factor 1 (IGF-1): a growth hormone – Molecular Pathology
- LeRoith D. & Roberts C.T. – The insulin-like growth factor system – Cancer Letters


