Insulin-like growth factor I, also known as somatomedin C, is the dominant effector of growth hormone and is structurally homologous to proinsulin. Human IGF-I is synthesized as two precursor isoforms with N- and alternate C‑terminal propeptides (1). These isoforms are differentially expressed by various tissues (1). The 7.6 kDa mature IGF‑I is identical between isoforms and is generated by proteolytic removal of the N- and C‑terminal regions. Mature human IGF-I shares 94% and 96% aa sequence identity with mouse and rat IGF-I, respectively (2), and exhibits cross-species activity. It shares 64% aa sequence identity with mature human IGF‑II. Circulating IGF-I is produced by hepatocytes, while local IGF-I is produced by many other tissues in which it has paracrine effects (1). IGF-I induces the proliferation, migration, and differentiation of a wide variety of cell types during development and postnatally (3). IGF-I regulates glucose and fatty acid metabolism, steroid hormone activity, and cartilage and bone metabolism (4‑7). It plays an important role in muscle regeneration and tumor progression (1, 8). IGF-I binds IGF-I R, IGF-II R, and the insulin receptor, although its effects are mediated primarily by IGF-I R (9). IGF-I association with IGF binding proteins increases its plasma half‑life and modulates its interactions with receptors (10).
IGF1 LR3 1mg
IGF1 LR3 allows for many of the growth-promoting effects of growth hormone insulin-like growth factors also know as IGF’s. IGF-1 LR3 comprises a family of peptides (protiens) that play important roles in mammalian growth and development. IGF1 LR3 is also known as Long R3 IGF-1 or Insulin-Like Growth Factor-I Long Arg3.
The Long R3 IGF-1 version is significantly more potent than regular IGF-1. The enhanced potency is due to the decreased binding of IGF1 LR3 to all known IGF binding proteins. These binding proteins normally inhibit the biological actions of IGF’s therefore IG-1 LR3 has been shown to have increased efficacy and function .
This IGF-1 LR3 analog of IGF-1 has been created with the purpose of increasing the biological activity of the IGF peptide.
IGF1 LR3 is also known as Long R3 IGF-1 or Insulin-Like Growth Factor-I Long Arg3. This is a human recombinant, single, non-glycosylated, polypeptide chain containing 83 amino acids and having a molecular mass of 9200 Daltons. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). The LR3 is a long-term analog of human IGF-1, specifically designed and manufactured for mammalian cell culture to support large-scale manufacturing of recombinant biopharmaceuticals. Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed ‘sulfation factor,’ which later became known as ‘somatomedin’.
IGF-1 LR3 is the primary protein involved in responses of cells to growth hormone (GH): that is, IGF-I is produced in response to GH and then induces cellular activities. One such example is muscle growth or hyperplasia. This compound also makes the human body more sensitive to insulin. It is the most potent growth factor found in the human body. IGF-1 causes muscle cell hyperplasia, which is an actual splitting and forming of new muscle cells.
The most effective form of IGF-1 is considered to be IGF-1 LR3. This formula has been chemically altered to avoid binding to proteins in the human body, and to increase the half life, approximately 20-30 hours.
The Sequence of IGF-1 LR3 and Muscle Growth
The polypeptide Long R3 Insulin-like Growth Factor-I (IGF1 LR3) is an 83 amino acid analog of IGF-I actually comprising the complete IGF-1 sequence but with the substitution of an Arginine (Arg) for the Glutamic Acid (Glu) at position 3, as well as a 13 amino acid extension peptide. This sequence change causes IGF-1 LR3 to avoid binding to proteins and allow it to have a much longer half life, around 20-30 hours. This analog of IGF-1 has been produced with the purpose of increasing the biological activity of the IGF peptide.” IGF stands for insulin-like growth factor. Among the effects the most positive are increased amino acid transport to cells, increased glucose transport, increased protein synthesis, and decreased protein degradation. When IGF is active it behaves differently in different types of tissues. In muscle cells proteins and associated cell components are stimulated. Protein synthesis is increased along with amino acid absorption. As a source of energy, IGF-1 LR3 mobilizes fat for use as energy in adipose tissue. In lean tissue, IGF-1 LR3 prevents insulin from transporting glucose across cell membranes. As a result the cells have to switch to burning off fat as a source of energy.
IGF-1 LR3 builds new muscle tissue by promoting nitrogen retention and protein synthesis. This causes the growth of muscles through both hyperplasia (which is an increase in number of muscle cells) and mitogenesis (which is the actual growth of new muscle fibers). Thus IGF-1 LR3 not only makes muscle fibers bigger, it makes more of them as well. Therefore, IGF can actually change the genetic capabilities in terms of muscle tissue and cell count. IGF increases and differentiates the number and types of cells present.
IGF-1 LR3 is a synthetic analog of the naturally existing insulin growth factor (IGF) which is a 93 amino acid residue. Modifications of the natural form occurred with the substitution of the Arg with Glu at the position 3, giving a code R3, and also an extension of a 13 amino acid at the B-terminus. Just like IGF-1, R3 has been shown to induce the development and growth of cells.
The studies on transgenic and knockout mice have shown that it can control its development and growth. It plays an important role as regulator in the G1 to S phase of the cell cycle. When applied to cardiomyocyte cultures, R3 have shown a large increase in proliferating cell nuclear antigen expression and in several cyclins involved in cell progression as well as in bromodeoxyuridien (BrdU) labeling (Kajstura et al. 1994). Other effects it has on cell lines are increased cell survival, inhibition of the apoptotic pathways, culture longevity and increased recombination of protein production (Fang et al. 1997). In another study, the application of the LR3 IGF-1 has led to an increase in the myocyte bromodeoxyuridine uptake by three to fivefold. But it has also shown that IGF-1 LR3 actions have been blocked by the ERK and P13K labeling which completely abolished the BrdU uptake. Furthermore, ut has been shown that in mycocytes, IGF-1 R3 stimulates the cardiomyocyte division in vivo (Sundgren et al. 2003). It has also been suggested that IGF-1-Long 3R is more potent than the IGF-1 because of its low binding capacity with all known IGF binding proteins (Tomas et al. 1995). In another investigation, feeding of LR3-IGF-1 in different amounts to investigate the effects on somatotropic axis (plasma levels of IGF-1 and 2, IGFBPs) was done. They have reported that plasma Long-R3 increased when administered subcutaneously but with no such behavior when administered orally. Furthermore, LR3 lowered the levels of native IGF-1 in rbGH-injected in calves, but L-R3 increased the amounts of IGF-II concentrations when administered with L-R3 subcutaneously. The parenteral administration of the Long R3 IGF-1 decreased the growth hormone concentration but did not affect the secretory system. It was also reported that the somatotrophic acis is basically functioning in neonatal calves and can be influenced by nutrition, growth hormone and Long-R3-IGF-1 (IGF1-LR3). (Hammon and Blum 1997).
The Half-Life of IGF-1 LR3 and its Effects of IGF-1
It has a considerably longer half-life than other form, nearly 20-30 hours. When IGF-1 LR3 is active, has multiple effects on tissues in muscle cells. It plays a essential role in muscle renewal. IGF-1 LR3 encourages both increase as well distinction of stem cells. IGF-1 LR3 increases satellite cell activity, muscle DNA, muscle protein content, muscle weight and muscle cross sectional area. The importance of IGF-1 LR3 lies in the fact that all of its obvious effects work to induce muscle growth. These effects are enhanced when combined with weight training.
Protein creation is better along with amino acid absorption as a source of energy. It enhances use of fat as energy. In lean tissue, IGF-1 LR3 prevents insulin form carrying glucose across cell membranes, as a result, the cells have to change to burning off fat as a source of energy. IGF-1 LR3 also mimics insulin in the human body.
Perhaps the most remarkable also strong influence it has on the human body is its ability to cause hyperplasia, which is an definite splitting of cells. Hypertrophy is what ensues during weight training; it is an increase in the size of muscle cells. Adult humans have a fixed number of muscle cells, that can become larger with training, however the number of muscle sells does not increase. But, with this preparation use you are able to induce hyperplasia which actually increases the number of muscle cells present in the muscle. Research studies show that with weight training the new cells develop faster and become stronger and more dense.
IGF-1 LR3 used in CLINICAL RESEARCH
IGF-1 LR3 plays an important part in childhood growth and continues to have results in adults. It is made in the human body and is at ideal levels during puberty. In most studies, the maximum active length for research studies IGF-1 LR3 is 50 days on also 20-40 days off. The most common range used during clinical research is typically between 20mcg to 120mcg per day.
During puberty, IGF is the most responsible for the natural muscle growth that occurs during these few years. There are many different things that IGF does in the human body; among the effects the most positive are increased amino acid transport to cells, increased glucose transport, increased protein synthesis, decreased protein degradation and increased RNA synthesis.
Perhaps the most interesting and potent effect IGF has on the human body is its ability to cause hyperplasia, which is an actual split-ting of cells.
In muscle cells, proteins and their cell components are stimulated. Protein synthesis is increased along with amino acid absorption. As a source of energy, IGF-1 mobilizes fat for use as energy in adipose tissue. In lean tissue, IGF prevents insulin from transporting glucose across cell membranes. As a result, the cells have to switch to burning off fat as a source of energy.
Recombinant Human IGF-I Protein
|Details of Functionality
||Measured in a serum-free cell proliferation assay using MCF‑7 human breast cancer cells. Karey, K.P. et al. (1988) Cancer Research 48:4083. The ED50 for this effect is 0.3-1.5 ng/mL.
The specific activity of recombinant human IGF-l is approximately 2.5 IU/μg, which is calibrated against recombinant human IGF-l WHO International Standard (NIBSC code: 91/554).
||E. coli-derived human IGF-I protein
||>97%, by SDS-PAGE under reducing conditions and visualized by silver stain.
||<0.10 EU per 1 μg of the protein by the LAL method.
Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
||7 kDa, reducing conditions
Packaging, Storage & Formulations
||Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
- 12 months from date of receipt, -20 to -70 °C as supplied.
- 1 month, 2 to 8 °C under sterile conditions after reconstitution.
- 3 months, -20 to -70 °C under sterile conditions after reconstitution.
||Lyophilized from a 0.2 μm filtered solution in PBS.
||>97%, by SDS-PAGE under reducing conditions and visualized by silver stain.
||Reconstitute at 200 μg/mL in sterile PBS.
Alternate Names for Recombinant Human IGF-I Protein, CF
- insulin-like growth factor 1 (somatomedin C)
- insulin-like growth factor 1
- insulin-like growth factor I
- insulin-like growth factor IA
- insulin-like growth factor IB
- Mechano growth factor
- Somatomedin A
- Somatomedin C