IGF-1LR3

Receptor Grade IGF-1 LR3 Peptide

Between 1940 and 1950, the growth hormone somatotropin was identified and researched. It was tentatively suggested that this hormone might enhance sulfate uptake in normal control rat serum, implying an increase in amino acid uptake or synthesis. However, this connection was not definitively established. This so-called “sulfate factor” was subsequently isolated from the rat serum and named “somatomedin.” Concurrently, an independent study explored the components responsible for producing insulin-like activity. It was hypothesized during this investigation that these components might be “somatomedins,” leading to the designation of these compounds as “insulin-like growth factors.”⁽¹⁾

Further explorations into the insulin-like growth factors involved gene-targeting approaches to potentially enhance their bioavailability and potency. During these studies, a variant called Receptor Grade IGF-1 LR3 was developed. This variant included an additional arginine residue and featured an elongated structure at the N-terminal (by 13 amino acids), resulting in a protein composed of 83 amino acids, compared to the 70 amino acids found in natural IGF-1.⁽¹⁾

Receptor Grade IGF-1 LR3 peptide, a polypeptide amino acid also known as Long arginine 3 IGF-1, or LR3-IGF-1, has been suggested to exhibit potential action similar to Insulin-like Growth factor-1, or IGF-1.⁽²⁾ IGF-1 is a naturally produced protein comprised of 70 amino acids. Structurally similar to insulin, this Receptor Grade IGF-1 LR3 has the potential primarily to regulate cell tissue and development. Several synthetic variations of IGF-1, such as recombinant IGF-1 (rhIGF-1), were developed to mimic the natural protein identically and stimulate similar actions as IGF-1. Another example is Receptor Grade IGF-1 LR3, which researchers speculate exhibits an increased affinity and anabolic potential while binding less to IGF-1 binding proteins (IGF-1BPs). This variant has been developed particularly for evaluation in cell growth studies. Moreover, the designation of Receptor Grade refers to the purity of the material, which is considered higher than Media Grade IGF-1 LR3.

Structurally, IGF-1 LR3 contains an extended N-terminal structure and arginine acid at residue 3. Hence, it is named IGF-1 Long R3.⁽³⁾ Owing to the altered structure, Receptor Grade IGF-1 LR3 has been suggested to bind poorly with IGF-binding proteins, shortening its duration of action.

Overview

IGF proteins appear to exert potential via binding with IGF-1 receptors; however, researchers posit that these IGF binding proteins, including Receptor Grade IGF-1 LR3, may function either via IGF receptor-dependent mechanism or via IGF-independent mechanisms.⁽¹⁾⁽⁴⁾

A study⁽¹⁾ was conducted where a murine model was exposed to the endogenous IGF-1 with IGF-1 LR3. During this study, it was suggested that upon exposure, the synthetic protein exhibited the potential to quickly clear the serum and distribute into tissues. Increased concentrations of the IGF-1 LR3 tracer were apparently detected in specific organs, including the kidneys, ovaries, and adrenal glands, in mouse models. This distribution pattern indicates that organs critical to metabolism and reproductive processes might have differing abilities to absorb or retain IGF-1 LR3 compared to IGF-I. It is proposed that these variations might arise due to IGF-1 LR3’s reduced tendency to bind with IGFBPs. IGFBPs are proteins that regulate the availability of IGFs in circulation, influencing their interaction with various tissues. The decreased binding of IGF-1 LR3 to IGFBPs may affect its bioavailability and interactions with specific tissues in research settings. Researchers suggest Receptor Grade IGF-1 LR3 has the potential to induce a signaling mechanism in the organism, either via autocrine mode (where the tissue cell stimulates itself) or via paracrine mode (where the tissue cell stimulates the nearby cell). The increased potential bioavailability of these autocrine and paracrine IGF-1 LR3 proteins may prove vital to inducing any possible action.

Chemical Makeup

Molecular Formula: C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉
Molecular Weight: 9117.5 g/mol
Other Known Titles: Long-(arg3) insulin-like growth factor-I, Insulin-like growth factor long chain R3