Tumor necrosis factor (TNF, cachexin, or cachectin, and formerly known as tumor necrosis factor-alpha or TNF-α) is a cytokine involved in systemic inflammation and is a member of a group of cytokines that stimulate the acute phase reaction.
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|Synonym:||Cachectin, TNF-alpha, TNFSF2, TNFA|
|MW (calculated):||44,017 daltons (monomer)|
|MW (reducing SDS-PAGE):||47 Kd|
|Abs 0.1% (= 1 mg/ml):||1.234|
Tumor necrosis factor (TNF, cachexin, or cachectin, and formerly known as tumor necrosis factor-alpha or TNF-α) is a cytokine involved in systemic inflammation and is a member of a group of cytokines that stimulate the acute phase reaction. It is produced primarily by activated M1 subtype macrophages as well as many other cell types as CD4+ lymphocytes, NK cells and neurons.
The primary role of TNF is in the regulation of immune cells. Tumor necrosis factor-α can be produced ectopically in the setting of malignancy and parallels parathyroid hormone both in causing secondary hypercalcemia and in the cancers with which excessive production is associated. The three-dimensional structure of TNF has been determined at 2.6 Å. TNF is a compact trimer composed of three identical subunits of 157 amino acids. This main chain fold corresponds to the 'jelly roll' motif observed in viral coat proteins such as VP1, VP2 and VP3 of rhinovirus, or the hemagglutinin molecule of influenza.
The subunits associate tightly about a threefold axis interacting through a simple edge-to-face packing of the beta-sandwich to form the solid, conical shaped trimer. The detailed three dimensional structure of TNF explains a wide range of observations, including antibody binding and site directed mutagenesis, and show that a region of biological importance situated at the interface between two subunits on the lower half (membrane proximal) of the trimer.
Amino Acid Sequence
1. Molecular cloning of the complementary DNA for human tumor necrosis factor. Wang A.M., Creasey A.A., Ladner M.B., Lin L.S., Strickler J., van Arsdell J.N., Yamamoto R., Mark D.F. Science 228:149-154 (1985)
2. The structure of tumor necrosis factor-alpha at 2.6 Å resolution. Implications for receptor binding. Eck M.J., Sprang S.R. J. Biol. Chem. 264:17595-17605 (1989)
3. The structure of tumour necrosis factor -- implications for biological function. Jones E.Y., Stuart D.I., Walker N.P., J. Cell Sci. Suppl. 13:11-18 (1990)
4. Crystal structure of TNF-alpha mutant R31D with greater affinity for receptor R1 compared with R2. Reed C., Fu Z.Q., Wu J., Xue Y.N., Harrison R.W., Chen M.J., Weber I.T. Protein Eng. 10:1101-1107 (1997)