What is TB-500?

TB-500 is a synthetic peptide based on the active region of thymosin beta-4, used in controlled experiments focused on actin-binding behaviour, cellular migration and cytoskeletal organisation. It serves as a research analogue for examining how thymosin-beta-4-related sequences influence structural and motility-associated cellular processes.

Research use only. TB-500 is supplied strictly for in-vitro laboratory research. This page does not describe dosing, administration, or use in humans or animals, and makes no therapeutic claims.

TB-500 is not thymosin beta-4

This is the distinction most sources blur, and it matters for anyone reading the literature.

Thymosin beta-4 (Tβ4) is a naturally occurring 43-amino-acid protein, one of the most abundant intracellular proteins in many cell types and the principal G-actin sequestering molecule in mammalian cells. It is the subject of a substantial published literature in its own right.

TB-500 is a shorter synthetic sequence based on the active region of that protein — the actin-binding portion rather than the whole molecule.

The practical consequence is that a paper on thymosin beta-4 is not automatically a paper on TB-500. Much of the secondary writing about TB-500 cites Tβ4 research directly, as though the fragment and the full protein were interchangeable. They are related but not identical: the full protein carries functions and interaction surfaces the fragment does not, so findings do not transfer without argument. When you trace a TB-500 claim to its source, check which molecule was actually used.

TB-500, TB500, TB-4, Tβ4 — which is which

The naming around this compound is unusually messy, and the variants are not all the same thing.

The first row is harmless: TB-500 and TB500 are the same thing and suppliers list both. The second row is where errors enter, because Tβ4 and TB-500 are routinely used as if interchangeable and they are not. A product listed as "thymosin beta-4" at research-peptide pricing is almost certainly the synthetic fragment rather than the recombinant full-length protein, which is a substantially more expensive material. If the distinction matters to your protocol, the certificate rather than the product name is what settles it.

The actin connection

The reason both molecules attract research interest is the same: actin.

Actin exists in two states — free monomers (G-actin) and polymerised filaments (F-actin) — and the balance between them governs cell shape, motility and structural reorganisation. Thymosin beta-4 binds G-actin monomers and holds them in a sequestered pool, which regulates how much monomer is available for polymerisation. In effect it acts as a buffer on the assembly reaction.

Sequences derived from its actin-binding region are therefore studied as tools for perturbing that balance experimentally. The research questions concern cytoskeletal dynamics — how cells reorganise their internal structure, how they migrate, and how those processes are regulated. Observed responses vary substantially with peptide concentration, exposure time, cell type and study design, which is why concentration is not an incidental detail when comparing two results.

What researchers study

In biochemical and cell-based systems, thymosin-beta-4-derived peptides are evaluated for their ability to interact with G-actin, affecting actin polymerisation and broader cytoskeletal remodelling. Typical research applications include:

• Investigating actin dynamics and cytoskeletal regulation
• In-vitro studies of cell migration and structural organisation
• Models assessing tissue architecture and repair-related signalling pathways

As with the fragment-versus-protein point above, the weight of this literature sits with Tβ4 rather than with TB-500 specifically. That is worth knowing before designing a protocol around it.

Why TB-500 and BPC-157 appear together

The two are studied as a pair more often than almost any other combination in this catalogue, and the rationale is that their mechanisms are unrelated.

BPC-157 is a synthetic pentadecapeptide used as a probe for peptide-mediated signalling. TB-500 acts on the actin cytoskeleton. A model examining structural reorganisation can therefore probe a signalling arm and a cytoskeletal arm in the same system without the two mechanisms confounding each other — which is the experimental reason the pairing recurs, rather than any established additive effect.

At a glance:

We supply the pair as the Wolverine Stack, and both compounds sit in the four-component Klow Stack alongside GHK-Cu and KPV. The BPC-157 vs TB-500 comparison sets the two side by side in more detail, and the BPC-157 guide covers that compound on its own.

One caution on the pairing: because the two are almost always sold and discussed together, a great deal of writing attributes results to "BPC-157 and TB-500" as a unit. A combined preparation cannot tell you which component produced an effect — that requires the compounds separately, which is why we supply both individually as well as blended.

TB-500 is prohibited in competitive sport

This belongs on the page, and most seller pages leave it off.

Thymosin beta-4 and its related fragments appear on the World Anti-Doping Agency Prohibited List, in the peptide hormones, growth factors and related substances category, prohibited at all times rather than in competition only. Anti-doping bodies including UKAD and USADA publish on it directly.

If you are a competing athlete or work with them, this is not a grey area, and the current WADA Prohibited List — which is revised annually — is the authority to check rather than any supplier page including this one.

It bears repeating that our material is supplied for in-vitro laboratory research and is not for human use in any context, competitive or otherwise.

What the critical literature says

TB-500 attracts sceptical commentary as well as promotional writing, and a researcher should read both.

The substantive criticisms are consistent: the direct evidence base for the fragment is much thinner than for the full protein; a great deal of the enthusiasm derives from preclinical and animal work that has not translated; and material sold online is of variable provenance, which makes independent replication difficult. Those are fair points and they are the reason batch documentation matters more here than for a better-characterised compound.

None of this makes it uninteresting as a research tool. It does mean claims about what TB-500 achieves should be traced to a source using TB-500, at a stated concentration, in a stated model.

Handling and stability

TB-500 is a peptide and behaves like one: temperature-sensitive, degraded by repeated freeze-thaw cycling, and best kept cold and consistently so.

Our TB-500 ships as a pre-mixed solution rather than lyophilised powder, which removes the reconstitution step where most avoidable variability enters — water choice, added volume, mixing and the delay before first use all differ between benches. Store refrigerated at 2–8°C. The peptide calculator handles concentration arithmetic from the vial.

Dosing and administration

We publish no dosing, reconstitution-for-use or administration guidance for TB-500. It is supplied strictly for in-vitro laboratory research and is not for human or veterinary use, so quantity guidance aimed at a person would be inconsistent with what is actually supplied. Experimental concentrations are specific to the model and endpoint and belong in the primary literature.

How it is supplied

TB-500 is supplied as a pre-mixed solution with a batch-specific Certificate of Analysis recording measured purity for the lot you receive, dispatched from our UK facility under cold-chain handling and stored refrigerated at 2–8°C. Recent certificates are viewable in the COA library before ordering.

It is also a component of the Wolverine Stack — paired with BPC-157 — and of the Glow Stack and Klow Stack. For UK supply detail, strengths and trade volumes, see the TB-500 product page.

Related reading

• What is the Wolverine Stack?
• What is BPC-157?
• BPC-157 vs TB-500