Human tumor necrosis factor α (TNFα) mutants with exclusive specificity for the 55-kDa or 75-kDa TNF receptors

Abstract

To probe the ligand receptor interface, a number of point mutations were introduced in selected regions of human tumor necrosis factor (TNF) α by site-directed mutagenesis. The mutated proteins were expressed in Escherichia coli and analyzed for selective binding to recombinant 55- and 75-kDa TNF receptors in competition with radiolabeled wild-type TNF‡. Generally, mutations in the loop from position 29 to 34 and at positions 86 and 146 preferentially impaired binding to the 75-kDa TNF receptor, whereas mutations in the region from 143 to 145 mainly affected binding to the 55-kDa TNF receptor. Mutation of the conserved Tyr87 resulted in a dramatic loss of binding activity to both receptors. ..