The BED finger which was named after the drosophila proteins BEAF and DREF, is found in one or more copies in cellular regulatory factors and transposases from plants, animals and fungi. The BED finger is an about 50 to 60 amino acid residues domain that contains a characteristic motif with two highly conserved aromatic positions, as well as a shared pattern of cysteines and histidines that is predicted to form a zinc finger. As diverse BED fingers are able to bind DNA, it has been suggested that DNA-binding is the general function of this domain [1].

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

• Animal, fungal and plant AC1 and Hobo-like transposases.
• Caenorhabditis elegans protein dpy-20, a predicted cuticular-gene transcriptional regulator.
• Drosophila BEAF (boundary element-associated factor), which is thought to be involved in chromatin insulation.
• Drosophila DREF, a transcriptional regulator for S-phase genes.
• Tobacco 3AF1 and tomato E4/E8-BP1, which are light- and ethylene-regulated DNA binding proteins that contain two BED fingers [2,3].