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PROSITE documentation PDOC00866 [for PROSITE entry PS01125]

ROK family signature


A family of bacterial proteins has been described [1] which groups transcriptional repressors, sugar kinases and yet uncharacterized open reading frames. This family, known as ROK (Repressor, ORF, Kinase) currently consist of:

  • Xylose operon repressor (gene xylR) in Bacillus subtilis, Lactobacillus pentosus and Staphylococcus xylosus.
  • N-acetylglucosamine repressor (gene nagC) from Escherichia coli.
  • Glucokinase (EC (gene glk) from Streptomyces coelicolor.
  • Fructokinase (EC (gene scrK or frk) from Pediococcus pentosaceus, Streptococcus mutans and Zymomonas mobilis.
  • Escherichia coli allokinase (EC (gene alsK).
  • Escherichia protein mlc.
  • Hypothetical Escherichia coli protein yajF and HI0182, the corresponding Haemophilus influenzae protein.
  • Hypothetical Escherichia coli protein yhcI and HI0144, the corresponding Haemophilus influenzae protein.
  • A hypothetical protein in nagH 5'region from Clostridium perfringens.

The repressor proteins (xylR and nagC) from this family possess a N-terminal region not present in the sugar kinases and which contains an helix-turn-helix DNA-binding motif. The domain common to all these proteins consists of about 300 residues. It is not highly conserved, but we could define a pattern centered on a glycine-rich region in the central part of the domain.

Last update:

December 2004 / Pattern and text revised.

Technical section

PROSITE method (with tools and information) covered by this documentation:

ROK, PS01125; ROK family signature  (PATTERN)


1AuthorsTitgemeyer F., Reizer J., Reizer A., Saier M.H. Jr.
TitleEvolutionary relationships between sugar kinases and transcriptional repressors in bacteria.
SourceMicrobiology 140:2349-2354(1994).
PubMed ID7952186

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