DT-A(R) corresponds to a mutated version of the catalytic A subunit encoded by the Corynephage beta Diphtheria toxin (DT) gene (UniProtKB:P00588), in which a translational stop has been introduced at codon 155. DT-A(R) was originally selected as a temperature-sensitive cell ablation tool in Saccharomyces cerevisiae (FBrf0055894). FBrf0055894 reports that when expressed in transgenic Drosophila, DT-A(R) appears to be temperature-sensitive, showing stronger effects at 18[o]c than at 25[o]C, although variable results were obtained depending on the insertion line used. However, a subsequent paper (FBrf0123036) reported that cell ablation was ineffective when DT-A(R) was expressed in the ovary.