What is IGF-1?

IGF-1 (Insulin-like growth factor 1), also called Somatomedin 1, IGF-I, IGFI,  IGF1, IGF-IA, and mechano growth factor, was named for its close resemblance to proinsulin. IGF-1 is encoded by the IGF1 gene. IGF-1 is comprised of 70 amino acids with a molecular weight of 7649 Da. It’s amino acid sequence is GPETLCGAEL VDALQFVCGD RGFYFNKPTGYGSSSRRAPQ TGIVDECCFR SCDLRRLEMY CAPLKPAKSA. It is an important peptide for growth throughout the lifecycle of mammals.

How It Works

IGF-1 is most commonly generated by the liver in response to production of growth hormone by the pituitary gland, but it can be produced in the fetus and other tissues for localized purposes. IGF-1 has been shown to play a critical role in cell growth, apoptosis (programmed cell death), cell division, and the transfer of glucose across cell membranes. Interestingly, it is found to have the opposite effect on adipose (fat) tissue. IGF-1 inhibits the growth of adipose tissue while restricting glucose transport which encourages animal test subjects to burn adipose tissue for energy. Deficiency in IGF-1 development has been shown to result in short stature and impaired fetal development.

The use of IGF-1 changes over time in animal test subjects. It’s impact slightly alters based on lifecycle:

  • Fetal: Important for growth during the third trimester
  • Childhood through puberty: Essential for height and cranial development
  • Post-puberty: Promotes muscle development

IGF-1 promotes the growth of cells in animal test subjects, especially in skeletal muscle, cartilage, bone, liver, kidney, nerves, skin, and lungs. IGF-1 levels in the bloodstream can help regulate bone growth and density.  It primarily operates by binding to the Insulin-like growth factor 1 receptor (IGF1 receptor), a tyrosine kinase receptor. It can also bind to the insulin receptor at roughly 0.1 times the potency of insulin.

Research Potential/Therapeutic Use

IGF-1 has been shown to have therapeutic use. Subjects with low levels of IGF-1 benefited from a treatment of growth hormone and insulin-like growth hormone-1.  The therapy saw improvements in height velocity but without abnormal bone maturation. IGF-1 has also been used in numerous studies for clinical and therapeutic use in conjunction with other conditions:

  • ALS
  • Rett syndrome
  • Autism
  • Heart disease
  • Prostate cancer
  • Multiple sclerosis
  • Muscular dystrophy

The multiple sclerosis study found that IGF-1 was able to suppress the progression of the autoimmune disease. It has the effect of increasing levels of T-reg cells in affected tissues which suppress the disease.  Muscular dystrophy experiments on rats found IGF-1 increased muscle retention and inhibited the development of fibrosis. This was attributed to IGF-1’s ability to proliferate and encourage satellite cells in the muscle to fuse existing muscle fibers and to repair damaged tissue.  The study on prostate cancer found that IGF-1 was beneficial to prostate cancer initiation. Oddly, prostate cancer cells also benefited from low levels of IGF-1.  Low levels gave the prostate cancer cells a higher survival rate.


Long arginine 3-IGF-1, also called Long r3 IGF-1, LR3 IGF, IGF1 LR3, LongArg3 IGF-1,  is a synthetic version of IGF-1. It differs from IGF-1 by having an additional 13 amino acids at its N-terminus making it 83 amino acids. There is also a substitution in the corresponding IGF-1 third position of glutamic acid for an arginine. It has a molecular weight of 9105.4 Da. It’s amino acid sequence is MFPAMPLSSL FVNGPRTLCG AELVDALQFVCGDRGFYFNK PTGYGSSSRR APQTGIV DEC CFRSCDLRRL EMYCAPLKPA KSA.

The difference in chemical composition makes the ability to bind to IGF proteins less efficient. The result is a 2.5 times increase in potency. Additionally, it has a prolonged half-life of 20-30 hours. IGF-1 LR3 is available now for research purposes in the Rasa Research peptide store.


DES (1-3) IGF-1, also named IGF-1 Des (1-3), IGF-1 Des 1-3, is another type of IGF-1 that occurs naturally and synthetically. It is missing the first three amino acids from the IGF-1 amino acid chain. It is composed of 67 amino acids and has a molecular weight of 7360.5 Da. The amino acid sequence is TLCGAELVDA LQFVCGDRGF YFNKPTGYGS SSRRAPQTGIVDECCFRSCD LRRLEMYCAP LKPAKSA.

The missing amino acids make it less effective at binding to IGF proteins, mostly because of the glutamate amino acid missing from position 3. The structural difference makes it 10x more potent than IGF-1.


IGF-1, and its variants, are essential for regular growth in mammals and the development of muscle mass later in life. They have wide clinical use to treat or induce different physical and muscle developmental issues. Rasa Research is proud to be provide these peptides for purchase for research purposes only.

All products purchased from Rasa Research are for laboratory and in vitro usage only.

The following articles are based on info collected from numerous sources. The info presented in these articles are not validated and may be based upon opinions. They are only for reference, and are not to be taken as factual.

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February 15, 2016 Research Articles, Research Peptides , , ,
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