IGF-1 LR3

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a synthetic analog of the naturally occurring IGF-1 protein. It features two key modifications: a substitution of arginine for glutamic acid at position 3 (R3) and the addition of a 13-amino-acid extension peptide at the N-terminus (Long). These modifications dramatically reduce its binding affinity to IGF-binding proteins (IGFBPs), resulting in a much longer half-life and greater bioavailability than native IGF-1.

IGF-1 LR3 activates the IGF-1 receptor (IGF-1R), a tyrosine kinase receptor that triggers the PI3K/Akt and MAPK signaling pathways. These pathways promote protein synthesis, cell proliferation, and inhibition of apoptosis. Due to its reduced IGFBP binding (less than 1% affinity compared to native IGF-1), a much higher proportion of administered IGF-1 LR3 remains in the active, unbound form, making it approximately 2-3 times more potent than native IGF-1.

Research has explored IGF-1 LR3's effects on muscle growth, cell proliferation, and tissue repair. Studies have demonstrated its ability to promote hyperplasia (increase in cell number) in muscle tissue, distinguishing it from hypertrophy-only agents. It has been used extensively in cell culture research to support cell growth and is studied for potential applications in muscle wasting disorders and tissue engineering. Its potency requires careful consideration in research settings.