What Is the 13-Amino-Acid Extension in IGF-1 LR3?
Published 2026-07-11 · REVIVE Peptides Research Desk · 1 min read
Short answer: The 13-amino-acid extension in IGF-1 LR3 is a synthetic sequence added to the N-terminal (starting) end of native IGF-1's 70-amino-acid chain, bringing the analog's total length to 83 amino acids. Combined with the Arg3 substitution, this extension is the structural feature responsible for IGF-1 LR3's reduced binding to IGF-binding proteins.
In peptide chemistry, the N-terminal end of a chain is often a key site that binding partners — in this case, IGF-binding proteins — use to recognize and grip a target molecule. Extending this region with additional residues sterically interferes with that recognition without disturbing the separate part of the molecule the IGF-1 receptor binds to.
This 13-residue addition is why IGF-1 LR3 is 83 amino acids long in total, compared to native IGF-1's 70. It is a deliberate, single design choice made by the researchers who originally engineered the analog specifically to solve the IGFBP-sequestration problem discussed elsewhere on this site, not an incidental or naturally occurring variation.
This is a structural-chemistry explanation only. It does not describe any dosing, administration, or handling instruction, and REVIVE LAB UAE does not sell IGF-1 LR3.
Not sold by REVIVE LAB UAE. This page is published for research-education purposes only. IGF-1 LR3 is not part of the REVIVE LAB UAE product catalog and no order can be placed for it on this site.
Research-Use Only Disclaimer: This page is published for laboratory and scientific research information purposes only. Nothing here constitutes medical advice, dosing guidance, or a therapeutic recommendation. Products supplied by REVIVE LAB UAE (revivelab.ae) — where applicable — are sold strictly as reference materials for research use, not for human or veterinary consumption. Buyers and readers are solely responsible for compliance with applicable UAE laws and institutional research ethics requirements.