Home / Research library / IGF-1 LR3
Compound guide
IGF-1 LR3: what the research covers
Long R3 IGF-1 is the growth factor itself, modified twice: one substitution to escape its binding proteins, one extension to slow its clearance. Both changes exist to make a short-lived molecule usable.
What IGF-1 LR3 is
Native insulin-like growth factor 1 is seventy residues long. IGF-1 LR3 is eighty-three: the native sequence with glutamic acid at position three replaced by arginine, plus a thirteen-residue extension at the amino terminus derived from methionyl porcine growth hormone.
The arginine substitution is the functional one. In circulation, most IGF-1 is captured by IGF-binding proteins, which hold it in reserve and keep free concentrations low. Arginine at position three markedly reduces that capture, so a larger fraction of the molecule remains available to the receptor. The extension contributes additional resistance to clearance.
Its target is IGF-1R, a receptor tyrosine kinase signalling through PI3K and Akt and through the MAPK cascade — pathways concerned with protein synthesis, proliferation and the suppression of apoptosis.
Separating growth hormone from its messenger
Much of what growth hormone does, it does through IGF-1 produced in the liver. That makes attribution awkward: an effect observed after somatropin or after a secretagogue could be receptor-mediated at the GH receptor, or entirely downstream.
Supplying IGF-1 directly resolves the ambiguity. An effect present with IGF-1 LR3 and absent with GH receptor blockade is IGF-mediated; an effect that survives the reverse arrangement is not. This is the main reason the compound appears in study designs alongside growth hormone rather than instead of it.
The same logic connects it to MGF, which is not a separate growth factor at all but an alternatively spliced product of the same IGF-1 gene, acting locally where IGF-1 LR3 acts systemically.
How Amino Club supplies it
Supplied lyophilised in sealed vials as IGF-1 LR3, specified at 99% purity or better by HPLC with identity confirmed by mass spectrometry and released against the batch Certificate of Analysis. The lab testing page documents that process.
At eighty-three residues with three disulfide bridges this is a folded protein, and it is handled as one: kept cold, not agitated, prepared in small working volumes and not refrozen. The thirteen-residue extension and the single residue substitution are both invisible on a purity trace, so the mass determination is what actually establishes that the vial contains LR3 rather than native IGF-1. Diluent options are under reconstitution supplies.
Related reading
IGF-1 LR3 sits in the growth hormone research peptides group with HGH 191AA, MGF, PEG-MGF and the secretagogues ipamorelin and MK-677.
Every guide is indexed in the research library. Certificates and storage are covered on the FAQ, quantity pricing through bulk and wholesale.
Research use only
IGF-1 LR3 supplied by Amino Club is a laboratory reference material. It is not a medicine, not a supplement, and not for human or veterinary use, and no dosing guidance or administration protocol is provided. The full terms are in the research use policy.