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IGF-1 LR3
What it is
IGF-1 LR3 is an 83 amino acid protein: the full 70 amino acid human IGF-1, with arginine in place of glutamic acid at position 3 and a 13 amino acid extension at the front. Natural IGF-1 spends almost all its time locked to six IGF-binding proteins and acts for minutes when free. The R3 swap and the extension cut binding-protein grip more than a hundredfold, so LR3 stays free and active far longer. It works on the same IGF-1 receptor as the body's own hormone.
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)
- The amino acid sequence of human insulin-like growth factor I and its structural homology with proinsulin (Abstract · checked 2026-10-13)