Members of this family assume an OB fold, which consists of a highly curved five-stranded beta-sheet that closes on itself to form a beta-barrel. OB1 has a shallow groove formed by one face of the curved sheet and is demarcated by two loops, one between beta 1 and beta 2 and another between beta 4 and beta 5, which allows for weak single strand DNA binding. The domain also binds the 70-amino acid DSS1 (deleted in split-hand/split foot syndrome) protein, which was originally identified as one of three genes that map to a 1.5-Mb locus deleted in an inherited developmental malformation syndrome [1].

1: BRCA2 function in DNA binding and recombination from a BRCA2-DSS1-ssDNA structure. Yang H, Jeffrey PD, Miller J, Kinnucan E, Sun Y, Thoma NH, Zheng N, Chen PL, Lee WH, Pavletich NP; Science 2002;297:1837-1848. PMID:12228710