Thymosin beta-4

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Available structures
PDB Human UniProt search: PDBe RCSB
Aliases TMSB4X, FX, PTMB4, TB4X, TMSB4, thymosin beta 4, X-linked
External IDs GeneCards: 7114
RNA expression pattern
PBB GE TMSB4X 216438 s at tn.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr X: 12.98 – 12.98 Mb n/a
PubMed search [1] n/a
View/Edit Human

Thymosin beta-4 is a protein that in humans is encoded by the TMSB4X gene.[2][3][4]

The protein consists (in humans) of 43 amino acids (msdkpdmaei ekfdksklkk tetqeknplp sketieqekq ages) and has a molecular weight of 4921 g/mol.[5]


This gene encodes an actin sequestering protein which plays a role in regulation of actin polymerization. The protein is also involved in cell proliferation, migration, and differentiation. This gene escapes X inactivation and has a homolog on chromosome Y (TMSB4Y).[4]

Clinical significance[edit]

It has been studied in a number of clinical trials.[6]

The thymosin beta-4 peptide, if used after a heart attack, might reactivate cardiac progenitor cells to repair damaged heart tissue.[7][8]

Doping in Sports[edit]

Thymosin beta-4 was allegedly used by some players in various Australian football codes and is under investigation by the Australian Sports Anti-Doping Authority for anti-doping violations.[9][10]

Players of the Essendon Football Club were cleared of use of Thymosin Beta 4 on March 30, 2015 by the Australian Football League anti-doping tribunal, however after an appeal by the World Anti-Doping Agency, this was overturned on the January 12, 2016.[11]


TMSB4X has been shown to interact with ACTA1[12][13] and ACTG1.[14][15]

See also[edit]


  1. ^ "Human PubMed Reference:". 
  2. ^ Gómez-Márquez J, Dosil M, Segade F, Bustelo XR, Pichel JG, Dominguez F, Freire M (Oct 1989). "Thymosin-beta 4 gene. Preliminary characterization and expression in tissues, thymic cells, and lymphocytes". Journal of Immunology. 143 (8): 2740–4. PMID 2677145. 
  3. ^ Lahn BT, Page DC (Oct 1997). "Functional coherence of the human Y chromosome". Science. 278 (5338): 675–80. Bibcode:1997Sci...278..675L. doi:10.1126/science.278.5338.675. PMID 9381176. 
  4. ^ a b "Entrez Gene: TMSB4X thymosin, beta 4, X-linked". 
  5. ^ "protein NP_066932". NCBI. 
  6. ^ Crockford D, Turjman N, Allan C, Angel J (Apr 2010). "Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications". Annals of the New York Academy of Sciences. 1194: 179–89. Bibcode:2010NYASA1194..179C. doi:10.1111/j.1749-6632.2010.05492.x. PMID 20536467. 
  7. ^ Smart N, Bollini S, Dubé KN, Vieira JM, Zhou B, Davidson S, Yellon D, Riegler J, Price AN, Lythgoe MF, Pu WT, Riley PR (Jun 2011). "De novo cardiomyocytes from within the activated adult heart after injury". Nature. 474 (7353): 640–4. doi:10.1038/nature10188. PMC 3696525free to read. PMID 21654746. Lay summaryBBC News. 
  8. ^ British Heart Foundation. "Regenerative science: Mending Broken Hearts". YouTube Video. 
  9. ^ Koh B. "Cronulla Sharks and thymosin beta-4 … is it doping?". The Conversation. 
  10. ^ Ho EN, Kwok WH, Lau MY, Wong AS, Wan TS, Lam KK, Schiff PJ, Stewart BD (Nov 2012). "Doping control analysis of TB-500, a synthetic version of an active region of thymosin β₄, in equine urine and plasma by liquid chromatography-mass spectrometry". Journal of Chromatography A. 1265: 57–69. doi:10.1016/j.chroma.2012.09.043. PMID 23084823. 
  11. ^ "Essendon supplements saga: ASADA backs Court of Arbitration for Sport decision to upheld WADA appeal". ABC News (Australian Broadcasting Corporation). 
  12. ^ Ballweber E, Hannappel E, Huff T, Stephan H, Haener M, Taschner N, Stoffler D, Aebi U, Mannherz HG (Jan 2002). "Polymerisation of chemically cross-linked actin:thymosin beta(4) complex to filamentous actin: alteration in helical parameters and visualisation of thymosin beta(4) binding on F-actin". Journal of Molecular Biology. 315 (4): 613–25. doi:10.1006/jmbi.2001.5281. PMID 11812134. 
  13. ^ Safer D, Sosnick TR, Elzinga M (May 1997). "Thymosin beta 4 binds actin in an extended conformation and contacts both the barbed and pointed ends". Biochemistry. 36 (19): 5806–16. doi:10.1021/bi970185v. PMID 9153421. 
  14. ^ Hertzog M, van Heijenoort C, Didry D, Gaudier M, Coutant J, Gigant B, Didelot G, Préat T, Knossow M, Guittet E, Carlier MF (May 2004). "The beta-thymosin/WH2 domain; structural basis for the switch from inhibition to promotion of actin assembly". Cell. 117 (5): 611–23. doi:10.1016/S0092-8674(04)00403-9. PMID 15163409. 
  15. ^ Van Troys M, Dewitte D, Goethals M, Carlier MF, Vandekerckhove J, Ampe C (Jan 1996). "The actin binding site of thymosin beta 4 mapped by mutational analysis". The EMBO Journal. 15 (2): 201–10. PMC 449934free to read. PMID 8617195. 

Further reading[edit]