Inhibition of protein synthesis by diphtheria toxin induces a peculiar pattern of synthesized protein species

Abstract

The irreversible inhibition of overall protein synthesis induced by diphtheria toxin in mammalian cells is accompanied by a peculiar pattern of synthesized protein species during the early stages of cell intoxication. This pattern closely resembles patterns of synthesized protein species observed in cells treated with reversible inhibitors of protein synthesis acting at different levels. Synthesized proteins are in the M r range of 70–100 and 20–40 kDa. A 50-kDa protein, the most represented species, exhibits a peptide map identical to that of the 50-kDa species observed in cells treated with cycloheximide and hypertonic medium. The synthesis of these proteins is apparently regulated at both transcriptional and translational levels.