Thymosin is a hormone secreted from the thymus. Its primary function is to stimulate the production of T cells, which are an important part of the immune system. Thymosin also assists in the development of B cells to plasma cells to produce antibodies. The predominant form of thymosin, thymosin b4, is a member of a highly conserved family of actin monomer-sequestering proteins. b-thymosins are the primary regulators of unpolymerized actin, and are essential for maintaining the small cytoplasmic pool of free G-actin monomers required for rapid filament elongation and allowing for the flux of monomers between the thymosin-bound pool and F-actin.
Thymosin b4 is a 43 amino acid peptide which is regarded as the main intracellular G-actin sequestering peptide.It has a molecular weight of 4963.55 Da, and its molecular formula is: C212H350N56O78S1. Extracellular Thymosin b4 may contribute to physiological processes such as angiogenesis, wound healing, and regulation of inflammation. Thymosin b4 has an a.a. sequence of Ac-Ser-Asp-Lys-Pro-Asp-Met-Ala-Glu-Ile-Glu-Lys-Phe-Asp-Lys-Ser-Lys-Leu-Lys-Lys-Thr-Glu-Thr-Gln-Glu-Lys-Asn-Pro-Leu-Pro-Ser-Lys-Glu-Thr-Ile-Glu-Gln-Glu-Lys-Gln-Ala-Gly-Glu-Ser-OH.