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IGF-1 LR3 · How it works
Escaping the binding proteins
Over 95 percent of the body's IGF-1 is held by binding proteins, mostly IGFBP-3, and only free IGF-1 can work. The Arg-3 swap and the 13 amino acid extension make LR3 bind those proteins weakly. It stays free, reaches tissues and acts for hours. That is the whole reason it is stronger than natural IGF-1.
Sources
Read the original sources
- Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency (Abstract · checked 2026-10-13)
- Long R3 IGF-I, Repligen identity and cell-culture use (Identity and cell-culture sections · checked 2026-10-13)