This domain is found a a large family of transcriptional regulators. This domain specifically binds to autoinducer molecules (N-Acyl homoserine lactones, chlorolactone and rosmarinic acid) (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).