[Function, molecular structure and gene expression regulation of tumor necrosis factor and lymphotoxin]

Tumor necrosis factor (TNF, also called TNF-alpha) and lymphotoxin (LT, TNF-beta) have 32% homology in their primary structures, and it has recently been clarified that they also have closely related tertially structures. These two related cytokines share various biological functions, such as cytotoxic effect, immunomodulating effect, etc. although they produce different effects on several lymphoid, endothelial, and other cellular targets. In this paper, the structures of the two cytokines and their receptor binding sites are described. Furthermore, the structures of the two types of TNF receptors, as well as their role in TNF mediated signal transduction, and possible second messengers responsible for TNF action are also discussed.