This family, known as ROK (Repressor, ORF, Kinase) includes the xylose operon repressor, xylR, from Bacillus subtilis, Lactobacillus pentosus and Staphylococcus xylosus; N-acetylglucosamine repressor, nagC, from Escherichia coli; glucokinase from Streptomyces coelicolor; fructokinase from from Pediococcus pentosaceus, Streptococcus mutans and Zymomonas mobilis; allokinase and mlc from E. coli; and E. coli hypothetical proteins yajF and yhcI and the corresponding Haemophilus influenzae proteins. The repressor proteins (xylR and nagC) from this family possess an N-terminal region not present in the sugar kinases and which contains an helix-turn-helix DNA-binding motif.