This domain is named after the various transcriptional regulatory proteins that it contains, including MtrR (Swiss:Q6RV06), AcrR (Swiss:P34000), ArpR (Swiss:Q9KJC4), TtgR (Swiss:Q9AIU0) and SmeT (Swiss:Q8KLP4). These are members of the TetR family of transcriptional repressors, that are involved in the control of expression of multidrug resistance proteins [1,2,3]. This domain binds multiple drugs, antibiotics, flavonoids and indole (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).

1: Molecular analysis and nucleotide sequence of the envCD operon of Escherichia coli. Klein JR, Henrich B, Plapp R; Mol Gen Genet 1991;230:230-240. PMID:1720861

2: Identification and molecular characterization of an efflux system involved in Pseudomonas putida S12 multidrug resistance. Kieboom J, de Bont J; Microbiology 2001;147:43-51. PMID:11160799

3: Cloning and characterization of SmeT, a repressor of the Stenotrophomonas maltophilia multidrug efflux pump SmeDEF. Sanchez P, Alonso A, Martinez JL; Antimicrob Agents Chemother 2002;46:3386-3393. PMID:12384340