Peptide Academy · Research use only

Meet the families: the main types of research peptides

By BioLabs Research · Last reviewed October 2026

Map of different peptide chain shapes linked like a family tree

Peptide Academy · Chapter 2 of 7

Peptides come in families, a bit like dog breeds: same species, very different personalities. This chapter is a guided tour of the families researchers talk about most, and the ones you'll find in our catalog.

First, an honesty rule

"Scientists studied X" is not the same as "X works." Much of the research below was done in cells or animals, and many promising lab findings never hold up later. So for each family we tell you three things: where it comes from, what kind of research has been published, and how strong that evidence is. We don't tell you what any compound "does" for a person, because that's not what research material is for.

Compounds we don't stock are included too, because this is an academy, not a catalog. They get the same neutral treatment and no product links.

A quick guide to the evidence labels we use:

🧬 The repair-research pair: BPC-157 and TB-500

BPC-157 is a 15-amino-acid peptide, GEPPPGKPADDAGLV. It's described as a partial sequence of a protein found in human gastric juice, and the research group that first described it in the early 1990s is still the main source of papers on it[1][2].

TB-500 is the name used for a short, acetylated fragment of a protein called thymosin beta-4. The fragment's sequence is Ac-LKKTETQ, and it was characterised by liquid chromatography and mass spectrometry in a 2012 paper[3]. Thymosin beta-4 itself is known for binding actin, a protein that forms part of the cell's internal scaffolding; mutation studies mapped which part of the molecule does that[4].

What research has looked at: tissue and cell-migration models, mostly in animals. A 2025 independent narrative review of BPC-157 concluded that the literature is mainly preclinical and that only a few small human studies exist[5].

Evidence: Animal and lab studies. Early-stage, with much of BPC-157's literature from a small number of groups.

Catalog: BPC-157 · TB-500 · BPC-157 + TB-500 blend

📡 Coded receptor-signalling compounds: G1-S, G2-T and G3-R

Some research compounds are listed on our site under internal codes rather than names. G1-S, G2-T and G3-R are receptor-signalling research compounds. (G2-T is covered here for education only; it isn't currently in our catalog.) Receptor-signalling research is the most regulated family in 2026, so we deliberately keep descriptions on our site minimal: identity and testing data, nothing more.

Evidence: We don't summarise research for these codes in this series.

📈 The growth-signal group: Tesamorelin, CJC-1295 and Ipamorelin

These compounds are used to study the signals that prompt the pituitary gland to release growth hormone. They work through two different "locks":

Evidence: Varies by compound. CJC-1295 and Ipamorelin: mainly preclinical in the founding papers.

Catalog: Tesamorelin. CJC-1295 and Ipamorelin are included for education only; they aren't currently in our catalog.

🛡️ The thymus peptide: Thymosin Alpha-1

Thymosin alpha-1 is a 28-amino-acid peptide first isolated from calf thymus tissue and sequenced in 1977[16]. It comes from the start of a larger protein, prothymosin alpha[17]. Research has looked at its place in the biology of T cells, a type of immune cell[16]. Don't confuse it with thymosin beta-4 (the TB-500 parent): different family, different sequence.

Evidence: Lab and animal work on its biology. Included for education only; not currently in our catalog.

⚡ The mitochondria messenger: MOTS-c

Here's a plot twist. Most of your genes are in the DNA inside the cell's nucleus. But mitochondria, the cell's power plants, carry their own small, separate DNA. In 2015, researchers reported a short stretch of that mitochondrial DNA that codes for a 16-amino-acid peptide, which they named MOTS-c[6].

That finding raised a big research question: do mitochondria send their own signals to the rest of the cell? MOTS-c joined humanin as one of the first "mitochondrial-derived peptides"[7]. The original 2015 work was done in cells and mice[6].

Evidence: Early-stage. Mostly lab and animal work.

Catalog: MOTS-c

✨ The copper one: GHK-Cu

GHK is a tiny peptide, just three amino acids: glycine, histidine and lysine. It grabs a copper ion very tightly, forming GHK-Cu. It was first isolated from human plasma in 1973[8][9]. Since then it has built a long research history in cell studies and cosmetic science; a 2018 review notes it is widely used as an ingredient in skin and hair products[9].

Evidence: Mostly lab-based.

Catalog: GHK-Cu

🧠 The brain-signal pair: Semax and Selank

Semax is a seven-amino-acid peptide (Met-Glu-His-Phe-Pro-Gly-Pro) developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It is built from a fragment of a natural signalling hormone (ACTH 4–7) with a short Pro-Gly-Pro tail added; the tail was chosen to make the molecule harder for enzymes to break down[10]. Much of the published work comes from Russian research groups, including animal studies of gene activity in brain tissue[11].

Selank comes from the same institute. It's a seven-amino-acid peptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro): tuftsin, a natural four-amino-acid fragment of an antibody protein, with the same Pro-Gly-Pro tail added[18]. Published work includes mouse studies of gene activity in the spleen[18].

Evidence: Limited outside Russia. Mostly animal and lab work.

Catalog: Semax. Selank is included for education only; it isn't currently in our catalog.

🧪 The tiny fragment: KPV

KPV is just three amino acids: lysine, proline and valine. It's the tail end of alpha-melanocyte-stimulating hormone (alpha-MSH), a natural signalling peptide. A 2008 study looked at how KPV gets into intestinal and immune cells, using cell lines and mouse models[19].

Evidence: Lab and animal studies. Included for education only; not currently in our catalog.

🔬 The fragment: AOD-9604

AOD-9604 is a modified piece of the end of the growth-hormone molecule: amino acids 177–191, with an extra tyrosine added at the front[12]. It was studied in rodent metabolism research in the early 2000s[12][13].

Evidence: Mainly preclinical. For its regulatory history, see Chapter 7.

Catalog: AOD-9604

Bonus: NAD+ (not actually a peptide)

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme, a helper molecule that every living cell uses in its energy chemistry. It isn't a peptide at all; it's built from nucleotides, not amino acids. We list it here because it sits in our catalog alongside peptides, and we'd rather be clear about that.

Catalog: NAD+

Frequently asked questions

What are the main types of research peptides? Common families include tissue-research peptides such as BPC-157 and TB-500, growth-signal compounds such as Tesamorelin, CJC-1295 and Ipamorelin, thymus peptides such as thymosin alpha-1, mitochondrial-derived peptides such as MOTS-c, copper-binding peptides such as GHK-Cu, brain-signal peptides such as Semax and Selank, and fragments such as AOD-9604 and KPV.

Is NAD+ a peptide? No. NAD+ is a coenzyme built from nucleotides, not amino acids.

Has BPC-157 been studied in people? An independent 2025 review found the literature is mainly preclinical, with only a few small human studies. We make no claims about use in people.

Do you sell every compound in this chapter? No. Some, such as G2-T, Selank, CJC-1295, Ipamorelin, KPV and thymosin alpha-1, are covered for education only and aren't currently in our catalog.

Why are some products listed only by a code? We list certain receptor-signalling research compounds by internal codes and keep their descriptions to identity and testing data.

Series navigation: ← Chapter 1: What are peptides? · Hub · Next: Chapter 3: Storage and stability →

For laboratory research use only. Not for human or veterinary use. Not a drug, food, cosmetic or dietary supplement. Nothing on this page is medical or legal advice.

References

  1. Sikiric P, et al. Stable gastric pentadecapeptide BPC 157, Robert's stomach cytoprotection/adaptive cytoprotection/organoprotection, and Selye's stress coping response. Curr Pharm Des / review, PMC7096228. pmc.ncbi.nlm.nih.gov/articles/PMC7096228
  2. Sikiric P, et al. Stable gastric pentadecapeptide BPC 157, somatosensory neurons… IntechOpen chapter 47147. intechopen.com/chapters/47147
  3. Esposito S, et al. Drug Test Anal. 2012;4(9):733–738. PMID 22962027
  4. Van Troys M, et al. EMBO J. 1996;15(2):201–210. PMID 8617195
  5. Regeneration or Risk? A Narrative Review of BPC-157 for Musculoskeletal Healing. 2025. PMC12446177. pmc.ncbi.nlm.nih.gov/articles/PMC12446177
  6. Lee C, et al. Cell Metab. 2015;21(3):443–454. doi:10.1016/j.cmet.2015.02.009
  7. Lee C, Kim KH, Cohen P. MOTS-c: a novel mitochondrial-derived peptide regulating muscle and fat metabolism. Free Radic Biol Med. 2016. PMC5116416
  8. Pickart L. A tripeptide in human serum that promotes the growth of hepatoma cells and the survival of normal hepatocytes. PhD thesis, UCSF, 1973 (as cited in ref 10)
  9. Pickart L, Margolina A. Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. Int J Mol Sci. 2018;19(7):1987. doi:10.3390/ijms19071987
  10. Synthetic peptides based on natural regulatory peptides (Semax). Neuroscience & Medicine, 2013. scirp.org/pdf/NM_2013120914223729.pdf
  11. Novel insights into the protective properties of ACTH(4-7)PGP (Semax) at the transcriptome level… in rats. PMC7350263
  12. Heffernan M, et al. Int J Obes. 2001. PMID 11673763 (rodent study of the modified hGH C-terminal fragment)
  13. Heffernan M, et al. Endocrinology. 2001. PMID 11713213 (rodent study of AOD9604)
  14. Jetté L, et al. Human growth hormone-releasing factor (hGRF)1–29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005;146(7):3052–3058. doi:10.1210/en.2004-1286
  15. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. doi:10.1530/eje.0.1390552
  16. Goldstein AL, et al. Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide. Proc Natl Acad Sci USA. 1977;74(2):725–729. PMID 265536
  17. Haritos AA, Goodall GJ, Horecker BL. Prothymosin alpha: isolation and properties of the major immunoreactive form of thymosin alpha 1 in rat thymus. Proc Natl Acad Sci USA. 1984;81(4):1008–1011. PMID 6583693
  18. Kolomin TA, et al. The temporary dynamics of inflammation-related genes expression under tuftsin analog Selank action. Mol Immunol. 2014;58(1):50–55. doi:10.1016/j.molimm.2013.11.002
  19. Dalmasso G, et al. PepT1-mediated tripeptide KPV uptake… Gastroenterology. 2008;134(1):166–178. PMID 18061177