Tumor Necrosis Factor-α LabCorp

Tumor necrosis factor-α (cachectin) and tumor necrosis factor-β (lymphotoxin) are two closely related proteins that share sequence homology of 34% in their amino acid sequence. Both mediators act on their target cells via the same receptors and, therefore, show similar, but not identical, biological effects. Under denaturing conditions TNF-α is a 17-kilodalton, nonglycosylated protein. The biologically active form of TNF-α is a trimer. Besides this soluble form of TNF-α, a 28-kilodalton membrane-bound form occurs on cell surfaces of TNF-producing cells, which may serve as a pool for soluble TNF-α and can be proteolytically cleaved from the cell surface.