Members of this family assume an OB fold, which consists of ahighly curved five-stranded beta-sheet that closes on itself toform a beta-barrel. OB3 has a pronounced groove formed by oneface of the curved sheet and is demarcated by two loops, onebetween beta 1 and beta 2 and another between beta 4 and beta 5,which allows for strong ssDNA binding [1]. BRCA2, oligonucleotide/oligosaccharide-binding, domain 3 BRCA-2_OB3