Long R3 Insulin-like Growth Factor-1 (IGF-1 LR3) is an 83-amino acid analog of human IGF-1, featuring a substitution of Arginine for Glutamic Acid at position 3 and a 13-amino acid extension peptide at the N-terminus. This structural configuration significantly downregulates its affinity for insulin-like growth factor-binding proteins (IGFBPs), allowing the observation of prolonged uninhibited binding to the IGF-1 receptor in skeletal muscle cell assays.
