<p>The many bacterial transcription regulation proteins which bind DNA through a 'helix-turn-helix' motif can be classified into subfamilies on the basis of sequence similarities. One of these subfamilies, called 'iclR', groups several proteins including:<ul> <li>gylR, a possible activator protein for the gylABX glycerol operon in Streptomyces.</li> </ul> <ul> <li>iclR, the repressor of the acetate operon (also known as glyoxylate bypass operon) in <taxon tax_id="562">Escherichia coli</taxon> and <taxon tax_id="602">Salmonella typhimurium</taxon>. </li> </ul> </p><p>These proteins havea Helix-Turn-Helix motif at the N terminus that is similar to that of other DNA-binding proteins [<cite idref="PUB00003813"/>].</p>