Long Arginine 3-IGF-1, often abbreviated as LR3IGF-1, represents a modified version of the naturally occurring growth factor, Insulin-like Growth Factor 1 (IGF-1). This synthetic variant is engineered to enhance the biological activity of IGF-1, primarily by increasing its potency and extending its half-life in the circulatory system. The "Long" in its name refers to the modification that prolongs its action, and "Arginine 3" indicates the replacement of the third amino acid in the native sequence with arginine, a change that significantly affects its interaction with IGF-binding proteins (IGFBPs).
IGF-1 is a hormone similar in molecular structure to insulin and plays a vital role in childhood growth and continues to have anabolic effects in adults. It mediates many of the growth-promoting effects of growth hormone (GH) released from the pituitary gland. By binding to its specific receptor, the IGF-1 receptor (IGF1R), it initiates intracellular signaling that promotes cell growth and division, differentiation, and a decrease in programmed cell death.
LR3IGF-1, with its alterations, is designed to bind less efficiently to IGFBPs, which normally inhibit the biological actions of IGF-1 by preventing its attachment to the IGF1R. This lower affinity for IGFBPs allows LR3IGF-1 to remain active in the bloodstream for a longer period than its endogenous counterpart, leading to prolonged and enhanced growth factor activity, including increased muscle mass and strength, improved regeneration and repair of skeletal muscle, and other tissues.
In research settings, LR3IGF-1 is used to study the effects of IGF-1 on cell cultures and animal models, providing insights into muscle development, bone density improvements, and neural function enhancement. Its properties make it a valuable tool for understanding the complex roles of growth factors in tissue growth, regeneration, and the overall regulation of body size and health.