IGF-1 LR3 1 mg

IGF-1 LR3 is an engineered analog of human insulin-like growth factor-I: a 13-amino-acid extension at the start and arginine in place of glutamate at position 3. The changes leave it binding IGF-binding proteins very weakly, which made it more potent than IGF-I in many test systems.

• IGF-I receptor and binding-protein research (cell studies)
• Protein synthesis and breakdown in muscle cells
• Growth and nitrogen retention in rats

It activates the IGF-I receptor. Because IGF-binding proteins barely hold it, more stays free to act - which is why it outperformed IGF-I in cells that secrete those binding proteins, but not in cells that do not.

1. Cells / in vitro

   Design and potency (J Mol Endocrinol 1992)

   In rat muscle cells the Long IGF-I analogs were more potent than IGF-I at stimulating protein and DNA synthesis and slowing protein breakdown. Long [Arg3]-IGF-I was the most potent in cells that secrete IGF-binding proteins, and less potent than IGF-I in cells that do not.[1]

2. Animal study

   Growth in rats (J Endocrinol 1993)

   Given to growing female rats for 14 days, it improved weight gain, nitrogen retention and feed efficiency as much as the highest IGF-I dose tested, at about one-sixth of that dose.[2]

3. Product testing

   Black-market vial (Growth Horm IGF Res 2010)

   Doping-control analysis of a black-market injection vial found a His-tagged form of Long R3 IGF-I of the kind made for biochemical studies; the authors note its effects in humans have not been described.[3]

4. Approved drug

   The approved IGF-1 medicine is a different molecule

   Mecasermin (Increlex), recombinant human IGF-1, was approved by the FDA on August 30, 2005. IGF-1 LR3 is not mecasermin.[4]

• No human studies of IGF-1 LR3 were identified.
• Products on this site are sold for laboratory research only. They are not the medicines used in the trials above, and those results do not apply to research material.

Is IGF-1 LR3 the same as Increlex?

No. Increlex is mecasermin, recombinant human IGF-1. IGF-1 LR3 is a longer analog with an amino-acid change that alters how it binds IGF-binding proteins.

1. 1.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 potencyFrancis GL et al. J Mol Endocrinol. 1992 Cells / in vitro
2. 2.Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female ratsTomas FM et al. J Endocrinol. 1993 Animal study
3. 3.Detection of His-tagged Long-R3-IGF-I in a black market productKohler M et al. Growth Horm IGF Res. 2010 Product testing
4. 4.Increlex (mecasermin) injection - original approval August 30, 2005U.S. FDA, Drugs@FDA: application 021839 Approved drug