Figure 1.

Representative subclasses of DNA-binding BEN factors. (A) The most well-characterized BEN factors include Drosophila and mammalian proteins that encode a single BEN domain and no other recognizable functional domains (“BEN-solo” factors). (B) Some BEN factors are fused to another known domain, such as the BTB domain; diverse BEN proteins bear other domains (Abhiman et al. 2008). (C) The conserved vertebrate protein BEND3 and a poxvirus protein (MCV) contain four BEN domains (“quad-BEN” factors). (D) Alignment of the four BEN domains of human BEND3 and MCV-M036R, human NACC1 and NACC2 BEN domains, and the Drosophila Insv-BEN domain, whose structure we solved (Dai et al. 2013a). Core motifs that define the BEN domain are evident, but these mammalian/viral BEN domains contain characteristic residues. Note that MCV-BD4 is most similar to BEND3-BD4.