PROSITE documentation PDOC50925
BLUF domain profile


The BLUF (for 'sensors of blue-light using FAD') domain is an about 90-residue FAD-binding domain involved in sensory transduction in microorganisms. The BLUF domain is mainly found in two branches of Bacteria, Proteobacteria and Cyanobacteria, but also in the eukaryotic unicellular flagellate Euglena gracilis. BLUF domain proteins can be divided into 'complex', multidomain proteins and 'short' proteins composed of a BLUF domain plus 30-70 additional amino acids with no significant similarity to known protein motifs. In complex proteins the BLUF domain can be linked to the adenyl cyclase, GGDEF (see <PDOC50887>) or EAL (see <PDOC50883>) domains. The BLUF domain is supposed to be involved in sensing blue-light (and possibly redox) using FAD and is similar to the flavin-binding PAS domains (see <PDOC50112>) and cryptochromes [1].

Some proteins known to contain a BLUF domain are listed below:

  • Rhodobacter sphaeroides protein appA.
  • Escherichia coli hypothetical protein ycgF.
  • Euglena gracilis α and β subunit of photoactivated adenylate cyclase (PAC) (EC

The profile we developed covers the entire BLUF domain.

Last update:

September 2003 / First entry.


Technical section

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

BLUF, PS50925; BLUF domain profile  (MATRIX)


1AuthorsGomelsky M. Klug G.
TitleBLUF: a novel FAD-binding domain involved in sensory transduction in microorganisms.
SourceTrends Biochem. Sci. 27:497-500(2002).
PubMed ID12368079

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