What Is TB-500?
TB-500 is a synthetic peptide. It copies an active part of Thymosin Beta-4 (Tβ4), a natural protein made of 43 amino acids.
Tβ4 is made by the TMSB4X gene. It is found in high levels in many mammal tissues.
The TB-500 fragment covers residues 17–23 of the full protein. This region holds the LKKTETQ motif. It is the main part that binds actin.
Key facts
- Molecular weight: about 4,963 Da
- Formula: C212H350N56O78S
- Form: freeze-dried (lyophilised) powder
- Solubility: dissolves in sterile water-based buffers at normal pH
Actin Binding and the LKKTETQ Motif
The main role of TB-500 is to bind single actin units, known as G-actin. It forms a 1:1 pair with each one.
This stops G-actin from joining into long actin chains (F-actin). As a result, the cell keeps a steady pool of free actin units.
The LKKTETQ sequence touches two areas of actin, called subdomains 1 and 3. It holds on through hydrogen bonds and water-repelling contacts.
X-ray studies have mapped this contact in fine detail. They help explain why TB-500 competes with profilin, another actin-binding protein, in cell-free tests.
Because of this, TB-500 is useful in research on:
- How the cell skeleton changes shape
- How cells form leading edges (lamellipodia)
- How cells move
Cell Migration Research
Lab tests such as scratch assays and transwell assays show that added TB-500 helps several cell types move in one direction:
- Skin cells (keratinocytes and fibroblasts) — scratch models closed faster. Levels of MMP enzymes and fibronectin also rose.
- Blood vessel cells (endothelial cells) — tube formation tests showed more tube growth. This gives a model for studying new vessel growth.
- Heart cells — rodent studies looked at how Tβ4 wakes up heart progenitor cells. This is relevant to heart tissue research.
Signalling Pathways
TB-500 does more than bind actin. Research suggests it also links to several signalling pathways inside the cell:
- ILK pathway: Tβ4 may bind integrin-linked kinase (ILK). This helps move ILK into the nucleus. In cell cultures, it then affects Akt and GSK-3β.
- PINCH–parvin complex: ILK, PINCH and parvin form a group linked to cell survival and cell anchoring. Researchers have studied how Tβ4 affects it in anoikis research (a type of cell death).
- HIF-1α: In low-oxygen cultures, Tβ4 has been linked to higher activity of HIF-1α target genes. This makes it relevant to oxygen-sensing research.
Research Grade Specifications
- Synthesis: solid-phase peptide synthesis (SPPS)
- Purity: ≥98% by reverse-phase HPLC
- Identity: confirmed by mass spectrometry, targeting the [M+2H]2+ charge state
- Storage: keep vials at −20 °C
- Reconstitution: use sterile water or PBS for cell-based assays
- Solubility: over 5 mg/mL in water-based buffer under standard lab conditions
TB-500 is supplied for research use only. Each batch comes with a full certificate of analysis. It is checked by an independent UKAS-accredited lab.
What TB-500 research has reported
TB-500 is the synthetic form of the active region of thymosin beta 4 (Tβ4). Tβ4 is a natural protein found in almost all human cells.
Tβ4 has been tested in human clinical trials, sponsored by RegeneRx. So there is more human data for it than for most research peptides. Note that those trials used medical Tβ4 products, not research-grade TB-500.
- Wound healing. Animal studies showed faster healing of skin wounds, burns and eye injuries. Phase 2 human trials of Tβ4 gel in leg and pressure ulcers found faster healing in some groups.
- Dry eye and corneal repair. Tβ4 eye drops (RGN-259) have completed Phase 3 trials. These covered dry eye disease and neurotrophic keratopathy.
- Heart and brain models. In rodents, it reduced damage and helped recovery after heart attack, stroke and spinal cord injury.
- Muscle and tendon. Animal studies showed more cell movement, less inflammation and better flexibility after injury. This is why TB-500 is often paired with BPC-157 in tissue repair research.
TB-500 side effects
In published human trials, Tβ4 was well tolerated. Side effects were similar to placebo for skin and eye use.
There is no matching safety data for research-grade TB-500 given by other routes. Points to note:
- Some papers raise concerns about its role in cell movement and new blood vessel growth. For this reason, it is not used in tumour research without a clear reason.
- TB-500 is banned in sport by WADA.
- Reports of headache, tiredness or injection-site irritation are anecdotal and unverified.
TB-500 with BPC-157
TB-500 and BPC-157 work in different ways:
- TB-500: binds actin and supports cell movement
- BPC-157: acts on growth factor and nitric oxide pathways
That is why the two are combined in soft tissue research. The mix is often called a “Wolverine” blend. When mixing a blended vial, use the peptide calculator to work out how much of each peptide is in each unit of volume.
TB-500 frequently asked questions
Is TB-500 the same as thymosin beta 4?
Not quite. TB-500 is a synthetic copy of the active part of thymosin beta 4. This is the LKKTETQ actin-binding region and the sequence around it. The full natural protein has 43 amino acids.
Is TB-500 legal in the UK?
It is not a controlled substance, so it can be sold for lab research. It is not a licensed medicine. It must not be supplied for human use, and it is banned in competitive sport.
What sizes does PeptidesNextDay stock?
We stock TB-500 2mg and TB-500 5mg. Both are freeze-dried, ≥98% pure and come with fast UK delivery. Research use only.