IGF-1 LR3 (Long R3 IGF-I, LR3IGF-I) is a recombinant analogue of human insulin-like growth factor I. It carries an N-terminal extension made up of the first 11 residues of methionyl porcine growth hormone followed by Val-Asn, and arginine in place of glutamic acid at position 3 of the IGF-I sequence, giving 83 residues in total. The analogue was engineered in Adelaide in the early 1990s to bind poorly to IGF-binding proteins (IGFBPs), and most of the published research dates from that period: cell culture potency assays, rat models of catabolism and gut growth, and plasma clearance and binding studies.