CRYSTAL-STRUCTURE OF THE SOLUBLE HUMAN 55 KD TNF RECEPTOR-HUMAN TNF-BETA COMPLEX - IMPLICATIONS FOR TNF RECEPTOR ACTIVATION

The X-ray crystal structure of the complex of the extracellular domain of the human 55 kd tumor necrosis factor (TNF) receptor with human TN Fbeta has been determined at 2.85 angstrom resolution. The complex has three receptor molecules bound symmetrically to one TNFbeta trimer. T he receptor fragment, a very elongated end to end assembly of four sim ilar folding domains, binds in the groove between two adjacent TNFbeta subunits. The structure of the complex defines the orientation of the ligand with respect to the cell membrane and provides a model for TNF receptor activation. The novel fold of the TNF receptor structure is likely to be representative of the nerve growth factor (NGF)/TNF recep tor family as a whole.