This family comprises the C-terminal portion of proteins that belong to the TetR family of transcriptional regulators. The C-terminus represents the regulatory region, and does not include the DNA binding helix-turn-helix domain. The target proteins that are repressed are involved in the transcriptional control of multi-drug efflux pumps, pathways for the biosynthesis of antibiotics, response to osmotic stress and toxic chemicals, control of catabolic pathways, differentiation processes, and pathogenicity. One of the target proteins is BetI, an osmoprotectant which controls the choline-glycine betaine pathway in E.coli.