IGF-1 LR3
Stocked in 0.1mg, 1mg at MontanaPep in Great Falls, Montana. Sold for laboratory research use only.
| Size | Catalog no. | Price per vial |
|---|---|---|
| 0.1mg | IG01 | $20 |
| 1mg | IG1 | $60 |
Classification
Recombinant 83-residue IGF-1 analogue engineered to evade binding-protein control
Structure and chemistry
IGF-1 LR3 is Long [Arg3] IGF-1: the 70-residue native human IGF-1 sequence carrying two deliberate changes. First, the glutamic acid at position 3 is replaced by arginine — this is the “Arg3” or “R3” in the name. Second, a hydrophobic 13-residue extension (Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn), derived from methionyl porcine growth hormone, is added at the N-terminus — this is the “Long.” The result is an 83-amino-acid protein of roughly 9,100 daltons, against roughly 7,650 for native IGF-1. Some suppliers describe the position-3 change backwards, as arginine being replaced; the peer-reviewed chemistry is a Glu-3 to Arg-3 substitution.
What the published research shows
The published work is biochemical and preclinical: recombinant protein characterization, NMR structural studies, cell-culture potency assays in rat L6 myoblasts, and rodent studies of body composition and organ growth. There are no human clinical trials of IGF-1 LR3.
Mechanism of action
Native IGF-1 circulates almost entirely bound to a family of six IGF binding proteins (IGFBP-1 through IGFBP-6), which act as gatekeepers controlling how much is free and receptor-available. Both engineered changes in LR3 target that gate: the Arg3 substitution sits in the binding-protein contact region, and the N-terminal extension adds further steric interference at the same interface. Affinity for the type 1 IGF receptor is essentially preserved while IGFBP binding is markedly reduced, so a far greater fraction stays free and active. NMR work confirmed the IGF-1 domain itself folds almost identically to native IGF-1.
Development history
Developed at GroPep Limited in Adelaide, Australia, as part of a program building recombinant fusion-protein analogues of IGF-1 specifically to separate the contributions of binding-protein affinity and receptor affinity to biological potency.
Current regulatory status
IGF-1 LR3 is not approved by any regulator for any indication and has no human clinical trial record. It has not been placed on FDA’s bulk drug substances lists. Because LR3 largely escapes IGF-binding-protein regulation, its receptor activation is sustained rather than buffered by the binding proteins that normally govern IGF-1 availability.
Analytical testing
This is an 83-residue protein with three disulfide bonds, not a short peptide, so correct folding is as much a part of identity as sequence. Published work on these analogues specifically documented mis-folded isomers that bound the receptor with as little as 0.5% of native affinity while appearing otherwise similar — a strong argument for mass spectrometry plus a folding-sensitive method rather than HPLC purity alone.
Ordering from Great Falls
MontanaPep, also known as Montana Peptides, is an independently owned supplier based at 715 13th Ave S, Great Falls, Montana. Local pickup is available by arrangement, and we ship to research addresses across Montana including Billings, Missoula, Bozeman, Helena, Butte, Kalispell and Havre. Call (406) 799-0812 or email customerservice@montanapep.com.