IGF-1 LR4 · How it works

Escaping the binding proteins

Most IGF-1 in the body is held by IGFBP-3 and other binding proteins and cannot act. The long-R3 design weakens that grip, so the analog stays free. Free IGF-1 reaches tissues and works for hours instead of minutes. That makes the family far stronger than natural IGF-1 dose for dose.

Sources

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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)