IGF-1 LR3

IGF-1 LR3 is a synthetic 83-residue peptide whose sequence corresponds to human insulin-like growth factor 1 with two deliberate structural changes: an extension at the amino terminus and an arginine substitution at position three. The name records both, the L for the long form created by the extension and the R3 for the arginine at the third position. Older papers spell it Long R3 IGF-I. It is supplied strictly for laboratory research use and is not for human or veterinary use.

The parent molecule is a single-chain polypeptide of the insulin superfamily, folded through internal disulfide bonds and studied largely in the context of its interactions with insulin-like growth factor binding proteins. Both modifications in this analogue sit in the amino-terminal region that the binding-protein literature treats as the principal contact surface, which is why the analogue and the native factor are so often run side by side in the same experiment.

The catalogue lists the molecular formula C400H625N111O115S9, whose nine sulphur atoms reflect the cysteine and methionine content of the chain. No CAS registry number and no molecular weight are recorded in this catalogue entry, so neither is stated here; the expected mass used for analytical comparison is calculated from the formula. The material is filed under cell-biology research materials and stocked in a 1 mg presentation.