DT-A(M) corresponds to a mutated version of the catalytic A subunit encoded by the Corynephage beta Diphtheria toxin (DT) gene (UniProtKB:P00588), into which a G53E amino acid replacement has been introduced. DT-A(M) was originally selected as a temperature-sensitive cell ablation tool, with FBrf0055894 reporting that the toxin is attenuated compared to wild-type DT-A and is also temperature-sensitive, showing cell ablation at 18[o]C but not at 25[o]C in transgenic Drosophila. However, a subsequent paper (FBrf0123036) reported that cell ablation was ineffective when DT-A(M) was expressed in the ovary.