β‐Thymosins
- 1 September 2007
- journal article
- review article
- Published by Wiley in Annals of the New York Academy of Sciences
- Vol. 1112 (1), 21-37
- https://doi.org/10.1196/annals.1415.018
Abstract
The development of thymosin beta(4) from a thymic hormone to an actin-sequestering peptide and back to a cytokine supporting wound healing will be outlined. Thymosin fraction 5 consists of a mixture of polypeptides and improves immune response. Starting with fraction 5, several main peptides (thymosin alpha(1), polypeptide beta(1), and thymosin beta(4)) were isolated and tested for biological activity. However, none of the isolated peptides were really thymic hormones. They are all biological important peptides with diverse functions. Polypeptide beta(1) is identical to ubiquitin truncated by two C-terminal glycine residues. Several peptides related to thymosin beta(4) were isolated and sequenced from various species. Large amounts of thymosin beta(4) were found in many cells. It was postulated that the beta-thymosins might have a general function. The identification of a biological function of thymosin beta(4) was tedious. In 1990, Dan Safer and his colleagues recognized that thymosin beta(4) sequesters G-actin. The dissociation constant of the complex in the micromolar range allows for fast binding and release of G-actin. beta-Thymosins are the main intracellular G-actin-sequestering peptides in most vertebrate cells. Thymosin beta(4) is unstructured but folds into a stable conformation on binding to G-actin. It is present in the nucleus as well as the cytoplasm and might be responsible for sequestering nuclear actin. Several biological effects are attributed to thymosin beta(4), oxidized thymosin beta(4), or to ac-SDKP possibly generated from thymosin beta(4). However, very little is known about molecular mechanisms mediating the effects attributed to extracellular beta-thymosins.Keywords
This publication has 85 references indexed in Scilit:
- Thymosin beta 4 suppression of corneal NFκB: A potential anti-inflammatory pathwayExperimental Eye Research, 2007
- Alterations in mitochondrial and cytosolic methionine sulfoxide reductase activity during cardiac ischemia and reperfusionExperimental Gerontology, 2006
- Nuclear Actin Extends, with No Contraction in SightMolecular Biology of the Cell, 2005
- Chemotherapeutic drugs change actin skeleton organization and the expression of β-thymosins in human breast cancer cellsZeitschrift für Krebsforschung und Klinische Onkologie, 2002
- Thymosin β4 serves as a glutaminyl substrate of transglutaminase. Labeling with fluorescent dansylcadaverine does not abolish interaction with G‐actin1FEBS Letters, 1999
- The dipyridyls paraquat and diquat attenuate the interaction of G-actin with thymosin β4FEBS Letters, 1998
- HPLC and post-column derivatization with fluorescamine: isolation of actin-sequestering β-thymosins by reversed-phase HPLCAnalytica Chimica Acta, 1997
- Oxidation and reduction of thymosin β4 and its influence on the interaction with G-actin studied by reverse-phase HPLC and post-column derivatization with fluorescamineAnalytica Chimica Acta, 1997
- Interactions of beta-Thymosins, Thymosin beta4-Sulfoxide, and N-terminally Truncated Thymosin beta4 with Actin Studied by Equilibrium Centrifugation, Chemical Cross-linking and ViscometryEuropean Journal of Biochemistry, 1995
- Enzyme Immunoassay Measurement of Thymosin β4Journal of Immunoassay, 1987