Review Structural and biological features of the TNF receptor and TNF ligand superfamilies: Interactive signals in the pathobiology of Hodgkin's disease*

Members of the TNF receptor superfamily are type I mem-brane glycoproteins with limited homology (overall homol-ogies: 25%-30%) in the extracellular domain containing variable numbers of cysteine-rich repeats. In contrast, the TNF ligand superfamily members (with the exception of LT-ct) are type II membrane glycoproteins with limited homol-ogy to TNF (overall homologies: 20%) in the extracellular region. TNF and LT-a are trimeric proteins and are com-posed of p-strands forming a p-jellyroll. the homology of the (3-strand regions for the TNF ligand superfamily members suggests a similar trimeric or multimeric complex formation for the other members. A genetic linkage, as evidence for evolutionary relatedness, is also found by chromosomal clus-ter for CD30, CD120b, 4-1BB and OX40 to Ip36; CD27, CD120a and TNFR-RP to 12pl3; TNF, LT-a and LT-p " t