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Peptide Profile
TB-500 is the active heptapeptide fragment of Thymosin Beta-4 — not identical, but structurally related. Molecular differences, G-actin binding domain, and research relevance compared.
Thymosin Beta-4 (Tβ4) is a naturally occurring 43-amino acid polypeptide found in nearly all tissues and cells of the human organism. It was first isolated from calf thymus in 1966 and is one of the most abundant intracellular peptides, with concentrations of up to 0.5 mM in platelets.
The primary biochemical function of Tβ4 is the sequestration of G-actin (monomeric actin) — it binds G-actin with high affinity, thereby regulating the balance between G-actin and F-actin (filamentous actin) within the cell.
TB-500 (Ac-LKKTETQ-NH₂) is a synthetic heptapeptide corresponding to the G-actin binding domain of Thymosin Beta-4 — amino acid residues 17 to 23 of the Tβ4 sequence. It is N-terminally acetylated and C-terminally amidated.
Important
TB-500 is not identical to Thymosin Beta-4. It is the isolated active fragment of the G-actin binding domain. The biochemical properties of the two compounds overlap but are not congruent.
The LKKTETQ sequence corresponds to the central motif of the G-actin binding domain in Thymosin Beta-4. This region is responsible for the interaction with G-actin — the peptide binds to the actin subunit and prevents its polymerization into F-actin.
In cell culture systems, TB-500 modulates actin dynamics, thereby influencing cellular processes dependent on cytoskeletal organization — including cell migration, cell adhesion, and intracellular transport.
Note
This article is for scientific information purposes only. It does not constitute medical advice. TB-500 is not an approved medicinal product and is intended exclusively for research purposes in authorized laboratory environments.