This family includes the Ldr (long direct repeat) toxins. In Escherichia coli there are four Ldr toxins, LdrA, LdrB, LdrC and LdrD. These toxins inhibit cell growth, decrease cell viability and cause nucleoid condensation. LdrD expression is inhibited by the antisense RNA RdlD, which functions as an antitoxin.
Jiyao W et al.(2023). "The conserved domain database in 2023.",