TB-500 vs Thymosin Beta-4: A Fragment and the Protein It Comes From

For research & educational purposes only. This article is a neutral, procedural reference for laboratory / in-vitro research handling — not medical advice or a usage recommendation. These materials are not for human or animal consumption.

The short answer

Thymosin beta-4 is a 43-amino-acid peptide found in nearly every cell, where it binds actin, the protein that forms the cell's internal scaffolding. TB-500 is a lab-made peptide based on the actin-binding region of thymosin beta-4 (the LKKTETQ sequence). The name is not used consistently across suppliers: some use TB-500 for the fragment, others for the full-length peptide. The identity line on a lot's certificate of analysis is what tells a researcher which one a vial contains.

	Thymosin beta-4	TB-500
Origin	Naturally occurring	Synthetic
Length	43 amino acids	Short fragment of the actin-binding region
Main activity studied	Actin binding, cell migration, tissue repair models	The actin-binding activity of that region
Published literature	Large, including clinical-stage work	Much thinner; often cites thymosin beta-4 studies

Related molecules, different sizes and literatures.

Thymosin beta-4: the full protein

Thymosin beta-4 was first isolated from thymus tissue, which gave it its name, but it was later found almost everywhere in the body. Its most-studied role is sequestering actin monomers, which regulates how cells build and remodel their internal scaffolding and how they move. Published research has studied it in wound, cardiac, corneal and other tissue-repair models.

TB-500: one region of it

The actin-binding activity of thymosin beta-4 maps to a short central region of the sequence. TB-500 is built on that region, which is why it is studied for the same actin-related activity in a smaller molecule. The important caveat is that much of the literature quoted for TB-500 was actually performed with full-length thymosin beta-4. Evidence for the whole protein is not automatically evidence for a fragment of it.

What this means for a research design

Check which molecule a study used before citing it for the other. Check which molecule a vial contains before designing around it: the certificate of analysis states the identity and the assayed amount for each lot.

Compounds referenced here are supplied as analytical-grade reference materials for in-vitro and laboratory research only. Nothing on this page is a recommendation for human or veterinary use.

Frequently asked questions

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

Not exactly. Thymosin beta-4 is a natural 43-amino-acid peptide. TB-500 refers to a synthetic peptide based on its actin-binding region, although some suppliers use the name for the full-length peptide. The identity on the certificate of analysis states which one a lot contains.

What does thymosin beta-4 do?

Its most-studied role is binding actin monomers, which regulates the cell's internal scaffolding and cell movement. It has been studied in a range of tissue-repair models.

Does research on thymosin beta-4 apply to TB-500?

Not automatically. Much of the literature quoted for TB-500 used full-length thymosin beta-4. Evidence for the whole protein is not direct evidence for a fragment of it.

Published research

A selection of peer-reviewed and clinical literature indexed on PubMed. Provided so qualified researchers can locate the primary sources — inclusion here is not a claim about any product or outcome.

VNG Research Team

VNG Labs supplies analytical-grade reference materials with lot-matched Certificates of Analysis. Our write-ups are neutral, source-cited references for qualified and independent researchers.