Why does IGF-1 LR3 last so much longer than natural IGF-1?

Its arginine substitution and N-terminal extension reduce binding to IGF-binding proteins and slow clearance, so it remains active in circulation for many hours rather than minutes.

What does the 'LR3' in the name mean?

LR3 stands for Long R3: 'Long' for the 13-amino-acid N-terminal extension and 'R3' for the arginine substituted at the third position, the two modifications that define this analog.

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Muscle Growth

Research Chemical

IGF-1 LR3

Also known as: IGF-1 LR3, Long R3 IGF-1, Receptor Grade IGF-1 LR3

IGF-1 LR3 (Long R3 IGF-1) is an engineered, long-acting analog of insulin-like growth factor 1 studied for sustained anabolic and tissue-growth signaling. Its modifications give it a far longer half-life than native IGF-1.

Mechanism of Action

IGF-1 LR3 carries an arginine substitution at position 3 plus a 13-amino-acid N-terminal extension, which sharply reduce its affinity for IGF-binding proteins and extend its circulating half-life. With prolonged availability of free peptide, it strongly and persistently activates the IGF-1 receptor (IGF-1R) tyrosine kinase, driving PI3K/Akt/mTOR and Ras/MAPK signaling that promotes protein synthesis, cell proliferation, and inhibition of apoptosis. This produces systemic, sustained anabolic effects in research models.

Half-life: Substantially extended versus native IGF-1; commonly cited around 20 to 30 hours
Administration Routes: subcutaneous
Research Status: Research Chemical