IGF-1 LR3 (0.1 Mg)

Native IGF-1 is rapidly cleared from circulation and tightly bound by IGF-binding proteins (IGFBPs), which limits its active lifespan. IGF-1 LR3 was modified in two critical ways:

• Arginine substitution at position 3 (Arg3)

• Extended peptide chain (Long R3)

These modifications:

• Greatly reduce binding to IGFBPs

• Extend half-life from minutes to many hours

• Increase bloavallability at target tissues

Conceptually: IGF-1 LR3 is designed to stay active longer and reach cells more effectively.

IGF-1 LR3 binds with high affinity to the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase expressed on many cell types, especially:

• Skeletal muscle cells

• Satellite (muscle stem) cells

• Bone and connective tissue cells

Receptor activation initiates powerful intracellular signaling cascades, primarily:

• PI3K > AKT > mTOR pathway

• MAPK/ERK pathway

These pathways regulate cell growth, survival, and protein synthesis.

A. Muscle Cells and Satellite Cells

IGF-1 LR3:

• Activates satellite cell proliferation

• Enhances myoblast differentiation

• Supports fusion of new nuclei into muscle fibers

This contributes to structural muscle remodeling, not just transient metabolic changes.

B. Protein Synthesis and Cell Survival

Through AKT-mTOR signaling, IGF-1 LR3:

• Increases ribosomal activity

• Promotes amino-acid uptake

• Suppresses apoptosis (programmed cell death)

The result is a strong anabolic and anti-catabolic cellular environment.