Sequence: 83 residues, single chain: a 13-residue N-terminal extension (Met plus porcine GH 1-11 plus Val-Asn) on human IGF-1 with Arg in place of Glu3; three disulfides (19-61, 31-74, 60-65)
Other names: Long R3 IGF-I, Long-(Arg3) insulin-like growth factor-I
The 7.6 kDa figure on some vendor sheets is native IGF-1, not LR3.