This family of bacterial transcriptional regulators includes the glycerol operon regulatory protein and acetate operon repressor both of which are members of the iclR family. These proteins have a Helix-Turn-Helix motif at the N-terminus. However this family covers the C-terminal region that binds to regulatory substrates including Glyoxylate, allantoin/ate, indole, aromatic hydrocarbons, sugar acids, succinic semialdehyde, benzoate derivatives, ascorbic acid, glycerol-3-phosphate, glyceraldehyde-3-phosphate and pyruvate (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).

1: Primary structure of the intergenic region between aceK and iclR in the Escherichia coli chromosome. Galinier A, Bleicher F, Negre D, Perriere G, Duclos B, Cozzone AJ, Cortay JC; Gene 1991;97:149-150. PMID:1995429

2: Structure and regulation of controlling sequences for the Streptomyces coelicolor glycerol operon. Smith CP, Chater KF; J Mol Biol 1988;204:569-580. PMID:3225846