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Growth Hormone•Anabolic Effector

📈IGF-1 LR3

Long-acting IGF-1 analogue with 20–30h half-life. Activates mTORC1, suppresses FOXO atrophy genes, and drives satellite cell proliferation. 1000× reduced IGFBP binding vs native IGF-1.

Amino acids
83
Mol. weight
9117 Da
Half-life
20–30 hours
Availability
In stock
Amino acid sequence
Modified IGF-1 with N-terminal Met extension + Arg3 substitution

What Is IGF-1 LR3?

IGF-1 LR3 is a recombinant analogue of endogenous IGF-1 with two modifications: N-terminal methionine extension and glutamic acid→arginine (R3) substitution. The R3 change reduces IGFBP binding affinity >1000×, extending half-life from ~12 minutes to 20–30 hours.

Key Mechanisms

  • PI3K→Akt→mTORC1 — phosphorylates S6K1 and 4E-BP1, driving ribosomal biogenesis and protein translation
  • Ras→MEK→ERK — cell cycle progression (G1→S via cyclin D1), DNA replication, differentiation
  • FOXO suppression — phosphorylates FOXO1/3a, blocking MuRF1 and Atrogin-1 transcription — prevents muscle proteolysis
  • Satellite cell activation — drives skeletal muscle stem cell proliferation and myofibre formation

Key References

  1. Coleman ME et al. "IGF-I stimulates muscle cell differentiation and myofiber hypertrophy." J Biol Chem, 1995;270:12109–12116.
  2. Foulstone EJ et al. "Role of IGFBP-3 in the IGF axis of human skeletal muscle." J Cell Physiol, 2003;196:229–240.

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