IGF-1 LR3
Also known as: igf1 lr3, igf-1 lr3, long r3 igf-1, long r3 igf1, insulin-like growth factor 1 lr3
Long-acting variant of IGF-1 studied for anabolic signaling, muscle hypertrophy, and satellite cell activation.
Quick Reference
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Overview
Synthetic protein
Long arginine 3-IGF-1, abbreviated as IGF-1 LR3 or LR3-IGF-1, is a synthetic protein and lengthened analogue of human insulin-like growth factor 1 (IGF-1). It differs from native IGF-1 in that it possesses an arginine instead of a glutamic acid at the third position in its amino acid sequence, and also has an additional 13 amino acids at its N-terminus (MFPAMPLLSLFVN) ("long"), for a total of 83 amino acids. The consequences of these modifications are that IGF-1 LR3 retains the pharmacological activity of IGF-1 as an agonist of the IGF-1 receptor, has very low affinity for the insulin-like growth factor-binding proteins (IGFBPs), and has improved metabolic stability. As a result, it is approximately three times more potent than IGF-1, and possesses a significantly longer half-life of about 20–30 hours.
Mechanism of Action
Binds IGF-1 receptors, promotes protein synthesis, inhibits apoptosis, stimulates muscle hypertrophy and fat metabolism.
What Researchers Are Saying
Community Reports - Not Medical Advice
The following is aggregated from public forums, Reddit, and research communities. These are anecdotal reports from researchers only - not verified clinical data and not a recommendation of any kind.
IGF-1 LR3 (also known as igf1 lr3, igf-1 lr3) is studied within the growth hormone axis and body composition research community. Long-acting variant of IGF-1 studied for anabolic signaling, muscle hypertrophy, and satellite cell activation.
Last updated October 28, 2026
Research status: active. IGF-1 LR3 appears across growth hormone axis and body composition research forums and academic literature. Researchers note this compound falls in the growth hormone category.
Last updated October 28, 2026
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