Peptide Info

What Is TB-500? Thymosin Beta-4 and Its Active Fragment

TB-500 is a synthetic peptide based on thymosin beta-4, one of the most abundant proteins inside our cells. This guide explains the full protein vs the fragment, why actin binding matters, and how it compares with BPC-157.

AussiePeptides Research Team 2 min read
TB-500 (TB500) 10mg peptide vial with AussiePeptides label

TB-500 and thymosin beta-4

Thymosin beta-4 (Tβ4) is a 43-amino-acid protein found in almost every human cell. Its main job is to hold on to actin, the protein that forms the cell's internal scaffolding, and release it when the cell needs to move or change shape.

TB-500 (also written TB 500 or TB500) is the research name for a synthetic peptide based on Tβ4. Depending on the supplier, it refers either to the full-length synthetic protein or to a short fragment around its actin-binding region (the sequence LKKTETQ, residues 17 to 23). The sequence on the Certificate of Analysis tells you which one you have, so check it before you compare results across suppliers. We stock TB-500 in 10mg vials.

Parent protein
Thymosin beta-4
Full length
43 amino acids
Key fragment
LKKTETQ (17-23)
Main role
Actin sequestering
WADA
Prohibited
Length compared (amino acids)
  • Thymosin beta-443
  • BPC-15715
  • TB-500 fragment7

A short history

  1. 1960sThymosins are first isolated from the thymus gland in studies of the immune system.
  2. 1981Thymosin beta-4 is sequenced and characterised.
  3. 1990sResearch shows Tβ4 is a major actin-binding protein found in most cells.
  4. 2000s onwardAnimal studies look at Tβ4 in cell migration and tissue repair models; the TB-500 name appears in research supply.

Why researchers study it

Because Tβ4 controls actin, it sits at the centre of how cells crawl, divide and reorganise. Animal and cell studies have looked at it in models of:

  • cell migration and blood vessel formation
  • tissue repair in skin, muscle, eye and heart models
  • inflammation signalling

Most of this work is preclinical, meaning in cells or animals rather than people.

TB-500 vs BPC-157

TB-500 BPC-157
Source Thymosin beta-4 (in most cells) A protein in gastric juice
Length 43 or 7 amino acids 15 amino acids
Best-known mechanism Actin binding and cell migration Studied in gut, tendon and vessel models
Common pairing With BPC-157 With TB-500

The two come from unrelated sources, which is why researchers often study them together. The pre-mixed BPC-157 + TB-500 blend is covered in BPC-157 vs TB-500.

Sport and TB-500

TB-500 and thymosin beta-4 are on the World Anti-Doping Agency prohibited list, and there have been positive tests in both human sport and horse racing. It is not an approved medicine.

Further reading

For laboratory research use only. Not for human consumption. Not medical or legal advice.

FAQ

Common questions

What is TB 500?

TB 500, usually written TB-500 or TB500, is a synthetic peptide based on thymosin beta-4, a protein that regulates actin inside cells. It is used in laboratory research.

What is TB500 made from?

It is synthesised in a lab to match either full thymosin beta-4 or its LKKTETQ fragment. It is not extracted from animal tissue.

Is TB-500 the same as thymosin beta-4?

Not always. Some suppliers sell the full 43-amino-acid protein as TB-500 and others sell a short active fragment. Check the sequence on the COA.

Is TB-500 banned in sport?

Yes. Thymosin beta-4 and its fragments are on the World Anti-Doping Agency prohibited list.

Keep reading